[patch 0/9] mm: memcontrol: naturalize charge lifetime v2

[patch 0/9] mm: memcontrol: naturalize charge lifetime v2

[Johannes Weiner]

Hi,

this is version 2 of the memcg charge naturalization series.  Changes
since v1 include:

o document mem_cgroup_account_move() exclusion
o catch uncharged swapin readahead pages in mem_cgroup_swapout()
o fix DEBUG_VM build after last-minute identifier rename
o drop duplicate lru_cache_add_active_or_unevictable() in THP migration
o make __GFP_NORETRY try reclaim at least once
o improve precharge failure path documentation (Michal)
o improve changelog on page_cgroup write ordering removal (Michal)
o document why kmem's page_cgroup writing is safe (Michal)
o clarify justification of the charge API rewrite (Michal)
o avoid mixing code move with logical changes (Michal)
o consolidate uncharge batching sections (Kame)
o rebase to latest mmots and add acks

These patches rework memcg charge lifetime to integrate more naturally
with the lifetime of user pages.  This drastically simplifies the code
and reduces charging and uncharging overhead.  The most expensive part
of charging and uncharging is the page_cgroup bit spinlock, which is
removed entirely after this series.

Here are the top-10 profile entries of a stress test that reads a 128G
sparse file on a freshly booted box, without even a dedicated cgroup
(i.e. executing in the root memcg).  Before:

    15.36%              cat  [kernel.kallsyms]   [k] copy_user_generic_string                  
    13.31%              cat  [kernel.kallsyms]   [k] memset                                    
    11.48%              cat  [kernel.kallsyms]   [k] do_mpage_readpage                         
     4.23%              cat  [kernel.kallsyms]   [k] get_page_from_freelist                    
     2.38%              cat  [kernel.kallsyms]   [k] put_page                                  
     2.32%              cat  [kernel.kallsyms]   [k] __mem_cgroup_commit_charge                
     2.18%          kswapd0  [kernel.kallsyms]   [k] __mem_cgroup_uncharge_common              
     1.92%          kswapd0  [kernel.kallsyms]   [k] shrink_page_list                          
     1.86%              cat  [kernel.kallsyms]   [k] __radix_tree_lookup                       
     1.62%              cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn                      

After:

    15.67%           cat  [kernel.kallsyms]   [k] copy_user_generic_string                  
    13.48%           cat  [kernel.kallsyms]   [k] memset                                    
    11.42%           cat  [kernel.kallsyms]   [k] do_mpage_readpage                         
     3.98%           cat  [kernel.kallsyms]   [k] get_page_from_freelist                    
     2.46%           cat  [kernel.kallsyms]   [k] put_page                                  
     2.13%       kswapd0  [kernel.kallsyms]   [k] shrink_page_list                          
     1.88%           cat  [kernel.kallsyms]   [k] __radix_tree_lookup                       
     1.67%           cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn                      
     1.39%       kswapd0  [kernel.kallsyms]   [k] free_pcppages_bulk                        
     1.30%           cat  [kernel.kallsyms]   [k] kfree                                     

As you can see, the memcg footprint has shrunk quite a bit.

The code has survived prolonged stress testing, including a swapping
workload being moved continuously between memcgs.

   text    data     bss     dec     hex filename
  38606   10084     400   49090    bfc2 mm/memcontrol.o.old
  35903   10084     400   46387    b533 mm/memcontrol.o.new

 Documentation/cgroups/memcg_test.txt |  160 +---
 include/linux/memcontrol.h           |   94 +--
 include/linux/page_cgroup.h          |   43 +-
 include/linux/swap.h                 |   15 +-
 kernel/events/uprobes.c              |    1 +
 mm/filemap.c                         |   13 +-
 mm/huge_memory.c                     |   55 +-
 mm/memcontrol.c                      | 1425 ++++++++++++----------------------
 mm/memory.c                          |   43 +-
 mm/migrate.c                         |   44 +-
 mm/rmap.c                            |   20 -
 mm/shmem.c                           |   32 +-
 mm/swap.c                            |   40 +
 mm/swap_state.c                      |    8 +-
 mm/swapfile.c                        |   21 +-
 mm/truncate.c                        |    9 -
 mm/vmscan.c                          |   12 +-
 mm/zswap.c                           |    2 +-
 18 files changed, 716 insertions(+), 1321 deletions(-)

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[patch 01/10] mm: memcontrol: fold mem_cgroup_do_charge()

[Johannes Weiner]

This function was split out because mem_cgroup_try_charge() got too
big.  But having essentially one sequence of operations arbitrarily
split in half is not good for reworking the code.  Fold it back in.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 166 ++++++++++++++++++++++----------------------------------
 1 file changed, 64 insertions(+), 102 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4df733e13727..c3c10ab98355 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2552,80 +2552,6 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
-
-/* See mem_cgroup_try_charge() for details */
-enum {
-	CHARGE_OK,		/* success */
-	CHARGE_RETRY,		/* need to retry but retry is not bad */
-	CHARGE_NOMEM,		/* we can't do more. return -ENOMEM */
-	CHARGE_WOULDBLOCK,	/* GFP_WAIT wasn't set and no enough res. */
-};
-
-static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
-				unsigned int nr_pages, unsigned int min_pages,
-				bool invoke_oom)
-{
-	unsigned long csize = nr_pages * PAGE_SIZE;
-	struct mem_cgroup *mem_over_limit;
-	struct res_counter *fail_res;
-	unsigned long flags = 0;
-	int ret;
-
-	ret = res_counter_charge(&memcg->res, csize, &fail_res);
-
-	if (likely(!ret)) {
-		if (!do_swap_account)
-			return CHARGE_OK;
-		ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
-		if (likely(!ret))
-			return CHARGE_OK;
-
-		res_counter_uncharge(&memcg->res, csize);
-		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
-		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
-	} else
-		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
-	/*
-	 * Never reclaim on behalf of optional batching, retry with a
-	 * single page instead.
-	 */
-	if (nr_pages > min_pages)
-		return CHARGE_RETRY;
-
-	if (!(gfp_mask & __GFP_WAIT))
-		return CHARGE_WOULDBLOCK;
-
-	if (gfp_mask & __GFP_NORETRY)
-		return CHARGE_NOMEM;
-
-	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
-	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
-		return CHARGE_RETRY;
-	/*
-	 * Even though the limit is exceeded at this point, reclaim
-	 * may have been able to free some pages.  Retry the charge
-	 * before killing the task.
-	 *
-	 * Only for regular pages, though: huge pages are rather
-	 * unlikely to succeed so close to the limit, and we fall back
-	 * to regular pages anyway in case of failure.
-	 */
-	if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret)
-		return CHARGE_RETRY;
-
-	/*
-	 * At task move, charge accounts can be doubly counted. So, it's
-	 * better to wait until the end of task_move if something is going on.
-	 */
-	if (mem_cgroup_wait_acct_move(mem_over_limit))
-		return CHARGE_RETRY;
-
-	if (invoke_oom)
-		mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize));
-
-	return CHARGE_NOMEM;
-}
-
 /**
  * mem_cgroup_try_charge - try charging a memcg
  * @memcg: memcg to charge
@@ -2642,7 +2568,11 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 {
 	unsigned int batch = max(CHARGE_BATCH, nr_pages);
 	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
-	int ret;
+	struct mem_cgroup *mem_over_limit;
+	struct res_counter *fail_res;
+	unsigned long nr_reclaimed;
+	unsigned long flags = 0;
+	unsigned long long size;
 
 	if (mem_cgroup_is_root(memcg))
 		goto done;
@@ -2662,44 +2592,76 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 
 	if (gfp_mask & __GFP_NOFAIL)
 		oom = false;
-again:
+retry:
 	if (consume_stock(memcg, nr_pages))
 		goto done;
 
-	do {
-		bool invoke_oom = oom && !nr_oom_retries;
+	size = batch * PAGE_SIZE;
+	if (!res_counter_charge(&memcg->res, size, &fail_res)) {
+		if (!do_swap_account)
+			goto done_restock;
+		if (!res_counter_charge(&memcg->memsw, size, &fail_res))
+			goto done_restock;
+		res_counter_uncharge(&memcg->res, size);
+		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
+		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
+	} else
+		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
 
-		/* If killed, bypass charge */
-		if (fatal_signal_pending(current))
-			goto bypass;
+	if (batch > nr_pages) {
+		batch = nr_pages;
+		goto retry;
+	}
 
-		ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
-					   nr_pages, invoke_oom);
-		switch (ret) {
-		case CHARGE_OK:
-			break;
-		case CHARGE_RETRY: /* not in OOM situation but retry */
-			batch = nr_pages;
-			goto again;
-		case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
-			goto nomem;
-		case CHARGE_NOMEM: /* OOM routine works */
-			if (!oom || invoke_oom)
-				goto nomem;
-			nr_oom_retries--;
-			break;
-		}
-	} while (ret != CHARGE_OK);
+	if (!(gfp_mask & __GFP_WAIT))
+		goto nomem;
 
-	if (batch > nr_pages)
-		refill_stock(memcg, batch - nr_pages);
-done:
-	return 0;
+	if (gfp_mask & __GFP_NORETRY)
+		goto nomem;
+
+	nr_reclaimed = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
+
+	if (mem_cgroup_margin(mem_over_limit) >= batch)
+		goto retry;
+	/*
+	 * Even though the limit is exceeded at this point, reclaim
+	 * may have been able to free some pages.  Retry the charge
+	 * before killing the task.
+	 *
+	 * Only for regular pages, though: huge pages are rather
+	 * unlikely to succeed so close to the limit, and we fall back
+	 * to regular pages anyway in case of failure.
+	 */
+	if (nr_reclaimed && batch <= (1 << PAGE_ALLOC_COSTLY_ORDER))
+		goto retry;
+	/*
+	 * At task move, charge accounts can be doubly counted. So, it's
+	 * better to wait until the end of task_move if something is going on.
+	 */
+	if (mem_cgroup_wait_acct_move(mem_over_limit))
+		goto retry;
+
+	if (fatal_signal_pending(current))
+		goto bypass;
+
+	if (!oom)
+		goto nomem;
+
+	if (nr_oom_retries--)
+		goto retry;
+
+	mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch));
 nomem:
 	if (!(gfp_mask & __GFP_NOFAIL))
 		return -ENOMEM;
 bypass:
 	return -EINTR;
+
+done_restock:
+	if (batch > nr_pages)
+		refill_stock(memcg, batch - nr_pages);
+done:
+	return 0;
 }
 
 /**
-- 
1.9.3

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Re: [patch 01/10] mm: memcontrol: fold mem_cgroup_do_charge()

[Michal Hocko]

On Thu 29-05-14 12:15:53, Johannes Weiner wrote:
> This function was split out because mem_cgroup_try_charge() got too
> big.  But having essentially one sequence of operations arbitrarily
> split in half is not good for reworking the code.  Fold it back in.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/memcontrol.c | 166 ++++++++++++++++++++++----------------------------------
>  1 file changed, 64 insertions(+), 102 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 4df733e13727..c3c10ab98355 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2552,80 +2552,6 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
>  	return NOTIFY_OK;
>  }
>  
> -
> -/* See mem_cgroup_try_charge() for details */
> -enum {
> -	CHARGE_OK,		/* success */
> -	CHARGE_RETRY,		/* need to retry but retry is not bad */
> -	CHARGE_NOMEM,		/* we can't do more. return -ENOMEM */
> -	CHARGE_WOULDBLOCK,	/* GFP_WAIT wasn't set and no enough res. */
> -};
> -
> -static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
> -				unsigned int nr_pages, unsigned int min_pages,
> -				bool invoke_oom)
> -{
> -	unsigned long csize = nr_pages * PAGE_SIZE;
> -	struct mem_cgroup *mem_over_limit;
> -	struct res_counter *fail_res;
> -	unsigned long flags = 0;
> -	int ret;
> -
> -	ret = res_counter_charge(&memcg->res, csize, &fail_res);
> -
> -	if (likely(!ret)) {
> -		if (!do_swap_account)
> -			return CHARGE_OK;
> -		ret = res_counter_charge(&memcg->memsw, csize, &fail_res);
> -		if (likely(!ret))
> -			return CHARGE_OK;
> -
> -		res_counter_uncharge(&memcg->res, csize);
> -		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
> -		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
> -	} else
> -		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
> -	/*
> -	 * Never reclaim on behalf of optional batching, retry with a
> -	 * single page instead.
> -	 */
> -	if (nr_pages > min_pages)
> -		return CHARGE_RETRY;
> -
> -	if (!(gfp_mask & __GFP_WAIT))
> -		return CHARGE_WOULDBLOCK;
> -
> -	if (gfp_mask & __GFP_NORETRY)
> -		return CHARGE_NOMEM;
> -
> -	ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
> -	if (mem_cgroup_margin(mem_over_limit) >= nr_pages)
> -		return CHARGE_RETRY;
> -	/*
> -	 * Even though the limit is exceeded at this point, reclaim
> -	 * may have been able to free some pages.  Retry the charge
> -	 * before killing the task.
> -	 *
> -	 * Only for regular pages, though: huge pages are rather
> -	 * unlikely to succeed so close to the limit, and we fall back
> -	 * to regular pages anyway in case of failure.
> -	 */
> -	if (nr_pages <= (1 << PAGE_ALLOC_COSTLY_ORDER) && ret)
> -		return CHARGE_RETRY;
> -
> -	/*
> -	 * At task move, charge accounts can be doubly counted. So, it's
> -	 * better to wait until the end of task_move if something is going on.
> -	 */
> -	if (mem_cgroup_wait_acct_move(mem_over_limit))
> -		return CHARGE_RETRY;
> -
> -	if (invoke_oom)
> -		mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(csize));
> -
> -	return CHARGE_NOMEM;
> -}
> -
>  /**
>   * mem_cgroup_try_charge - try charging a memcg
>   * @memcg: memcg to charge
> @@ -2642,7 +2568,11 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
>  {
>  	unsigned int batch = max(CHARGE_BATCH, nr_pages);
>  	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
> -	int ret;
> +	struct mem_cgroup *mem_over_limit;
> +	struct res_counter *fail_res;
> +	unsigned long nr_reclaimed;
> +	unsigned long flags = 0;
> +	unsigned long long size;
>  
>  	if (mem_cgroup_is_root(memcg))
>  		goto done;
> @@ -2662,44 +2592,76 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
>  
>  	if (gfp_mask & __GFP_NOFAIL)
>  		oom = false;
> -again:
> +retry:
>  	if (consume_stock(memcg, nr_pages))
>  		goto done;
>  
> -	do {
> -		bool invoke_oom = oom && !nr_oom_retries;
> +	size = batch * PAGE_SIZE;
> +	if (!res_counter_charge(&memcg->res, size, &fail_res)) {
> +		if (!do_swap_account)
> +			goto done_restock;
> +		if (!res_counter_charge(&memcg->memsw, size, &fail_res))
> +			goto done_restock;
> +		res_counter_uncharge(&memcg->res, size);
> +		mem_over_limit = mem_cgroup_from_res_counter(fail_res, memsw);
> +		flags |= MEM_CGROUP_RECLAIM_NOSWAP;
> +	} else
> +		mem_over_limit = mem_cgroup_from_res_counter(fail_res, res);
>  
> -		/* If killed, bypass charge */
> -		if (fatal_signal_pending(current))
> -			goto bypass;
> +	if (batch > nr_pages) {
> +		batch = nr_pages;
> +		goto retry;
> +	}
>  
> -		ret = mem_cgroup_do_charge(memcg, gfp_mask, batch,
> -					   nr_pages, invoke_oom);
> -		switch (ret) {
> -		case CHARGE_OK:
> -			break;
> -		case CHARGE_RETRY: /* not in OOM situation but retry */
> -			batch = nr_pages;
> -			goto again;
> -		case CHARGE_WOULDBLOCK: /* !__GFP_WAIT */
> -			goto nomem;
> -		case CHARGE_NOMEM: /* OOM routine works */
> -			if (!oom || invoke_oom)
> -				goto nomem;
> -			nr_oom_retries--;
> -			break;
> -		}
> -	} while (ret != CHARGE_OK);
> +	if (!(gfp_mask & __GFP_WAIT))
> +		goto nomem;
>  
> -	if (batch > nr_pages)
> -		refill_stock(memcg, batch - nr_pages);
> -done:
> -	return 0;
> +	if (gfp_mask & __GFP_NORETRY)
> +		goto nomem;
> +
> +	nr_reclaimed = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
> +
> +	if (mem_cgroup_margin(mem_over_limit) >= batch)
> +		goto retry;
> +	/*
> +	 * Even though the limit is exceeded at this point, reclaim
> +	 * may have been able to free some pages.  Retry the charge
> +	 * before killing the task.
> +	 *
> +	 * Only for regular pages, though: huge pages are rather
> +	 * unlikely to succeed so close to the limit, and we fall back
> +	 * to regular pages anyway in case of failure.
> +	 */
> +	if (nr_reclaimed && batch <= (1 << PAGE_ALLOC_COSTLY_ORDER))
> +		goto retry;
> +	/*
> +	 * At task move, charge accounts can be doubly counted. So, it's
> +	 * better to wait until the end of task_move if something is going on.
> +	 */
> +	if (mem_cgroup_wait_acct_move(mem_over_limit))
> +		goto retry;
> +
> +	if (fatal_signal_pending(current))
> +		goto bypass;
> +
> +	if (!oom)
> +		goto nomem;
> +
> +	if (nr_oom_retries--)
> +		goto retry;
> +
> +	mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch));
>  nomem:
>  	if (!(gfp_mask & __GFP_NOFAIL))
>  		return -ENOMEM;
>  bypass:
>  	return -EINTR;
> +
> +done_restock:
> +	if (batch > nr_pages)
> +		refill_stock(memcg, batch - nr_pages);
> +done:
> +	return 0;
>  }
>  
>  /**
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 02/10] mm: memcontrol: rearrange charging fast path

[Johannes Weiner]

The charging path currently starts out with OOM condition checks when
OOM is the rarest possible case.

Rearrange this code to run OOM/task dying checks only after trying the
percpu charge and the res_counter charge and bail out before entering
reclaim.  Attempting a charge does not hurt an (oom-)killed task as
much as every charge attempt having to check OOM conditions.  Also,
only check __GFP_NOFAIL when the charge would actually fail.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c3c10ab98355..46b3e37542ad 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2576,22 +2576,6 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 
 	if (mem_cgroup_is_root(memcg))
 		goto done;
-	/*
-	 * Unlike in global OOM situations, memcg is not in a physical
-	 * memory shortage.  Allow dying and OOM-killed tasks to
-	 * bypass the last charges so that they can exit quickly and
-	 * free their memory.
-	 */
-	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
-		     fatal_signal_pending(current) ||
-		     current->flags & PF_EXITING))
-		goto bypass;
-
-	if (unlikely(task_in_memcg_oom(current)))
-		goto nomem;
-
-	if (gfp_mask & __GFP_NOFAIL)
-		oom = false;
 retry:
 	if (consume_stock(memcg, nr_pages))
 		goto done;
@@ -2613,6 +2597,20 @@ retry:
 		goto retry;
 	}
 
+	/*
+	 * Unlike in global OOM situations, memcg is not in a physical
+	 * memory shortage.  Allow dying and OOM-killed tasks to
+	 * bypass the last charges so that they can exit quickly and
+	 * free their memory.
+	 */
+	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
+		     fatal_signal_pending(current) ||
+		     current->flags & PF_EXITING))
+		goto bypass;
+
+	if (unlikely(task_in_memcg_oom(current)))
+		goto nomem;
+
 	if (!(gfp_mask & __GFP_WAIT))
 		goto nomem;
 
@@ -2641,6 +2639,9 @@ retry:
 	if (mem_cgroup_wait_acct_move(mem_over_limit))
 		goto retry;
 
+	if (gfp_mask & __GFP_NOFAIL)
+		goto bypass;
+
 	if (fatal_signal_pending(current))
 		goto bypass;
 
-- 
1.9.3

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Re: [patch 02/10] mm: memcontrol: rearrange charging fast path

[Michal Hocko]

On Thu 29-05-14 12:15:54, Johannes Weiner wrote:
> The charging path currently starts out with OOM condition checks when
> OOM is the rarest possible case.
> 
> Rearrange this code to run OOM/task dying checks only after trying the
> percpu charge and the res_counter charge and bail out before entering
> reclaim.  Attempting a charge does not hurt an (oom-)killed task as
> much as every charge attempt having to check OOM conditions.  Also,
> only check __GFP_NOFAIL when the charge would actually fail.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/memcontrol.c | 33 +++++++++++++++++----------------
>  1 file changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c3c10ab98355..46b3e37542ad 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2576,22 +2576,6 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
>  
>  	if (mem_cgroup_is_root(memcg))
>  		goto done;
> -	/*
> -	 * Unlike in global OOM situations, memcg is not in a physical
> -	 * memory shortage.  Allow dying and OOM-killed tasks to
> -	 * bypass the last charges so that they can exit quickly and
> -	 * free their memory.
> -	 */
> -	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
> -		     fatal_signal_pending(current) ||
> -		     current->flags & PF_EXITING))
> -		goto bypass;
> -
> -	if (unlikely(task_in_memcg_oom(current)))
> -		goto nomem;
> -
> -	if (gfp_mask & __GFP_NOFAIL)
> -		oom = false;
>  retry:
>  	if (consume_stock(memcg, nr_pages))
>  		goto done;
> @@ -2613,6 +2597,20 @@ retry:
>  		goto retry;
>  	}
>  
> +	/*
> +	 * Unlike in global OOM situations, memcg is not in a physical
> +	 * memory shortage.  Allow dying and OOM-killed tasks to
> +	 * bypass the last charges so that they can exit quickly and
> +	 * free their memory.
> +	 */
> +	if (unlikely(test_thread_flag(TIF_MEMDIE) ||
> +		     fatal_signal_pending(current) ||
> +		     current->flags & PF_EXITING))
> +		goto bypass;
> +
> +	if (unlikely(task_in_memcg_oom(current)))
> +		goto nomem;
> +
>  	if (!(gfp_mask & __GFP_WAIT))
>  		goto nomem;
>  
> @@ -2641,6 +2639,9 @@ retry:
>  	if (mem_cgroup_wait_acct_move(mem_over_limit))
>  		goto retry;
>  
> +	if (gfp_mask & __GFP_NOFAIL)
> +		goto bypass;
> +
>  	if (fatal_signal_pending(current))
>  		goto bypass;
>  
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 03/10] mm: memcontrol: retry reclaim for oom-disabled and __GFP_NOFAIL charges

[Johannes Weiner]

There is no reason why oom-disabled and __GFP_NOFAIL charges should
try to reclaim only once when every other charge tries several times
before giving up.  Make them all retry the same number of times.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 46b3e37542ad..e8d5075c081f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2567,7 +2567,7 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 				 bool oom)
 {
 	unsigned int batch = max(CHARGE_BATCH, nr_pages);
-	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 	struct mem_cgroup *mem_over_limit;
 	struct res_counter *fail_res;
 	unsigned long nr_reclaimed;
@@ -2639,6 +2639,9 @@ retry:
 	if (mem_cgroup_wait_acct_move(mem_over_limit))
 		goto retry;
 
+	if (nr_retries--)
+		goto retry;
+
 	if (gfp_mask & __GFP_NOFAIL)
 		goto bypass;
 
@@ -2648,9 +2651,6 @@ retry:
 	if (!oom)
 		goto nomem;
 
-	if (nr_oom_retries--)
-		goto retry;
-
 	mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch));
 nomem:
 	if (!(gfp_mask & __GFP_NOFAIL))
-- 
1.9.3

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Re: [patch 03/10] mm: memcontrol: retry reclaim for oom-disabled and __GFP_NOFAIL charges

[Michal Hocko]

On Thu 29-05-14 12:15:55, Johannes Weiner wrote:
> There is no reason why oom-disabled and __GFP_NOFAIL charges should
> try to reclaim only once when every other charge tries several times
> before giving up.  Make them all retry the same number of times.

I have mentioned that already with the last iteration of the patch.
This can make THP charges stall unnecessarily when the allocation could
fall back to single page charges.
MEM_CGROUP_RECLAIM_RETRIES * SWAP_CLUSTER_MAX + CHARGE_BATCH * CPUS
reclaimed pages will not help for huge pages so multiple reclaims is
just pointless waisting of time.

I think you should just move the next patch in the series up and simply make
the thp charge __GFP_NORETRY:

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b3a6deed66d5..ba822c27a55b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3703,10 +3703,13 @@ int mem_cgroup_charge_anon(struct page *page,
 		nr_pages <<= compound_order(page);
 		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
 		/*
-		 * Never OOM-kill a process for a huge page.  The
-		 * fault handler will fall back to regular pages.
+		 * Never OOM-kill a process for a huge page. Also do not
+		 * reclaim memcg too much because it wouldn't help the
+		 * huge page charge anyway.
+		 * The fault handler will fall back to regular pages.
 		 */
 		oom = false;
+		gfp_mask |= __GFP_NORETRY;
 	}
 
 	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);


> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> ---
>  mm/memcontrol.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 46b3e37542ad..e8d5075c081f 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2567,7 +2567,7 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
>  				 bool oom)
>  {
>  	unsigned int batch = max(CHARGE_BATCH, nr_pages);
> -	int nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES;
> +	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
>  	struct mem_cgroup *mem_over_limit;
>  	struct res_counter *fail_res;
>  	unsigned long nr_reclaimed;
> @@ -2639,6 +2639,9 @@ retry:
>  	if (mem_cgroup_wait_acct_move(mem_over_limit))
>  		goto retry;
>  
> +	if (nr_retries--)
> +		goto retry;
> +
>  	if (gfp_mask & __GFP_NOFAIL)
>  		goto bypass;
>  
> @@ -2648,9 +2651,6 @@ retry:
>  	if (!oom)
>  		goto nomem;
>  
> -	if (nr_oom_retries--)
> -		goto retry;
> -
>  	mem_cgroup_oom(mem_over_limit, gfp_mask, get_order(batch));
>  nomem:
>  	if (!(gfp_mask & __GFP_NOFAIL))
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 04/10] mm: memcontrol: reclaim at least once for __GFP_NORETRY

[Johannes Weiner]

Currently, __GFP_NORETRY tries charging once and gives up before even
trying to reclaim.  Bring the behavior on par with the page allocator
and reclaim at least once before giving up.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e8d5075c081f..8957d6c945b8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2614,13 +2614,13 @@ retry:
 	if (!(gfp_mask & __GFP_WAIT))
 		goto nomem;
 
-	if (gfp_mask & __GFP_NORETRY)
-		goto nomem;
-
 	nr_reclaimed = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
 
 	if (mem_cgroup_margin(mem_over_limit) >= batch)
 		goto retry;
+
+	if (gfp_mask & __GFP_NORETRY)
+		goto nomem;
 	/*
 	 * Even though the limit is exceeded at this point, reclaim
 	 * may have been able to free some pages.  Retry the charge
-- 
1.9.3

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Re: [patch 04/10] mm: memcontrol: reclaim at least once for __GFP_NORETRY

[Michal Hocko]

On Thu 29-05-14 12:15:56, Johannes Weiner wrote:
> Currently, __GFP_NORETRY tries charging once and gives up before even
> trying to reclaim.  Bring the behavior on par with the page allocator
> and reclaim at least once before giving up.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/memcontrol.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e8d5075c081f..8957d6c945b8 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2614,13 +2614,13 @@ retry:
>  	if (!(gfp_mask & __GFP_WAIT))
>  		goto nomem;
>  
> -	if (gfp_mask & __GFP_NORETRY)
> -		goto nomem;
> -
>  	nr_reclaimed = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags);
>  
>  	if (mem_cgroup_margin(mem_over_limit) >= batch)
>  		goto retry;
> +
> +	if (gfp_mask & __GFP_NORETRY)
> +		goto nomem;
>  	/*
>  	 * Even though the limit is exceeded at this point, reclaim
>  	 * may have been able to free some pages.  Retry the charge
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 05/10] mm: memcontrol: catch root bypass in move precharge

[Johannes Weiner]

When mem_cgroup_try_charge() returns -EINTR, it bypassed the charge to
the root memcg.  But move precharging does not catch this and treats
this case as if no charge had happened, thus leaking a charge against
root.  Because of an old optimization, the root memcg's res_counter is
not actually charged right now, but it's still an imbalance and
subsequent patches will charge the root memcg again.

Catch those bypasses to the root memcg and properly cancel them before
giving up the move.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8957d6c945b8..184e67cce4e4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6485,8 +6485,15 @@ one_by_one:
 			cond_resched();
 		}
 		ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
+		/*
+		 * In case of failure, any residual charges against
+		 * mc.to will be dropped by mem_cgroup_clear_mc()
+		 * later on.  However, cancel any charges that are
+		 * bypassed to root right away or they'll be lost.
+		 */
+		if (ret == -EINTR)
+			__mem_cgroup_cancel_charge(root_mem_cgroup, 1);
 		if (ret)
-			/* mem_cgroup_clear_mc() will do uncharge later */
 			return ret;
 		mc.precharge++;
 	}
-- 
1.9.3

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Re: [patch 05/10] mm: memcontrol: catch root bypass in move precharge

[Michal Hocko]

On Thu 29-05-14 12:15:57, Johannes Weiner wrote:
> When mem_cgroup_try_charge() returns -EINTR, it bypassed the charge to
> the root memcg.  But move precharging does not catch this and treats
> this case as if no charge had happened, thus leaking a charge against
> root.  Because of an old optimization, the root memcg's res_counter is
> not actually charged right now, but it's still an imbalance and
> subsequent patches will charge the root memcg again.
> 
> Catch those bypasses to the root memcg and properly cancel them before
> giving up the move.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Michal Hocko <mhocko@suse.cz>

> ---
>  mm/memcontrol.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 8957d6c945b8..184e67cce4e4 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -6485,8 +6485,15 @@ one_by_one:
>  			cond_resched();
>  		}
>  		ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
> +		/*
> +		 * In case of failure, any residual charges against
> +		 * mc.to will be dropped by mem_cgroup_clear_mc()
> +		 * later on.  However, cancel any charges that are
> +		 * bypassed to root right away or they'll be lost.
> +		 */
> +		if (ret == -EINTR)
> +			__mem_cgroup_cancel_charge(root_mem_cgroup, 1);
>  		if (ret)
> -			/* mem_cgroup_clear_mc() will do uncharge later */
>  			return ret;
>  		mc.precharge++;
>  	}
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 06/10] mm: memcontrol: use root_mem_cgroup res_counter

[Johannes Weiner]

Due to an old optimization to keep expensive res_counter changes at a
minimum, the root_mem_cgroup res_counter is never charged; there is no
limit at that level anyway, and any statistics can be generated on
demand by summing up the counters of all other cgroups.

However, with per-cpu charge caches, res_counter operations do not
even show up in profiles anymore, so this optimization is no longer
necessary.

Remove it to simplify the code.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 149 ++++++++++++++++----------------------------------------
 1 file changed, 43 insertions(+), 106 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 184e67cce4e4..84195a80068c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2573,9 +2573,8 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
 	unsigned long nr_reclaimed;
 	unsigned long flags = 0;
 	unsigned long long size;
+	int ret = 0;
 
-	if (mem_cgroup_is_root(memcg))
-		goto done;
 retry:
 	if (consume_stock(memcg, nr_pages))
 		goto done;
@@ -2656,13 +2655,15 @@ nomem:
 	if (!(gfp_mask & __GFP_NOFAIL))
 		return -ENOMEM;
 bypass:
-	return -EINTR;
+	memcg = root_mem_cgroup;
+	ret = -EINTR;
+	goto retry;
 
 done_restock:
 	if (batch > nr_pages)
 		refill_stock(memcg, batch - nr_pages);
 done:
-	return 0;
+	return ret;
 }
 
 /**
@@ -2702,13 +2703,11 @@ static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
 static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
 				       unsigned int nr_pages)
 {
-	if (!mem_cgroup_is_root(memcg)) {
-		unsigned long bytes = nr_pages * PAGE_SIZE;
+	unsigned long bytes = nr_pages * PAGE_SIZE;
 
-		res_counter_uncharge(&memcg->res, bytes);
-		if (do_swap_account)
-			res_counter_uncharge(&memcg->memsw, bytes);
-	}
+	res_counter_uncharge(&memcg->res, bytes);
+	if (do_swap_account)
+		res_counter_uncharge(&memcg->memsw, bytes);
 }
 
 /*
@@ -2720,9 +2719,6 @@ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
 {
 	unsigned long bytes = nr_pages * PAGE_SIZE;
 
-	if (mem_cgroup_is_root(memcg))
-		return;
-
 	res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
 	if (do_swap_account)
 		res_counter_uncharge_until(&memcg->memsw,
@@ -3997,7 +3993,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
 	 * replacement page, so leave it alone when phasing out the
 	 * page that is unused after the migration.
 	 */
-	if (!end_migration && !mem_cgroup_is_root(memcg))
+	if (!end_migration)
 		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
 
 	return memcg;
@@ -4130,8 +4126,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent)
 		 * We uncharge this because swap is freed.  This memcg can
 		 * be obsolete one. We avoid calling css_tryget_online().
 		 */
-		if (!mem_cgroup_is_root(memcg))
-			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+		res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
 		mem_cgroup_swap_statistics(memcg, false);
 		css_put(&memcg->css);
 	}
@@ -4825,78 +4820,24 @@ out:
 	return retval;
 }
 
-
-static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
-					       enum mem_cgroup_stat_index idx)
-{
-	struct mem_cgroup *iter;
-	long val = 0;
-
-	/* Per-cpu values can be negative, use a signed accumulator */
-	for_each_mem_cgroup_tree(iter, memcg)
-		val += mem_cgroup_read_stat(iter, idx);
-
-	if (val < 0) /* race ? */
-		val = 0;
-	return val;
-}
-
-static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
-{
-	u64 val;
-
-	if (!mem_cgroup_is_root(memcg)) {
-		if (!swap)
-			return res_counter_read_u64(&memcg->res, RES_USAGE);
-		else
-			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
-	}
-
-	/*
-	 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
-	 * as well as in MEM_CGROUP_STAT_RSS_HUGE.
-	 */
-	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
-	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
-
-	if (swap)
-		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
-
-	return val << PAGE_SHIFT;
-}
-
 static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
-				   struct cftype *cft)
+			       struct cftype *cft)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
-	u64 val;
-	int name;
-	enum res_type type;
-
-	type = MEMFILE_TYPE(cft->private);
-	name = MEMFILE_ATTR(cft->private);
+	enum res_type type = MEMFILE_TYPE(cft->private);
+	int name = MEMFILE_ATTR(cft->private);
 
 	switch (type) {
 	case _MEM:
-		if (name == RES_USAGE)
-			val = mem_cgroup_usage(memcg, false);
-		else
-			val = res_counter_read_u64(&memcg->res, name);
-		break;
+		return res_counter_read_u64(&memcg->res, name);
 	case _MEMSWAP:
-		if (name == RES_USAGE)
-			val = mem_cgroup_usage(memcg, true);
-		else
-			val = res_counter_read_u64(&memcg->memsw, name);
-		break;
+		return res_counter_read_u64(&memcg->memsw, name);
 	case _KMEM:
-		val = res_counter_read_u64(&memcg->kmem, name);
+		return res_counter_read_u64(&memcg->kmem, name);
 		break;
 	default:
 		BUG();
 	}
-
-	return val;
 }
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -5376,7 +5317,10 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
 	if (!t)
 		goto unlock;
 
-	usage = mem_cgroup_usage(memcg, swap);
+	if (!swap)
+		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+	else
+		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
 
 	/*
 	 * current_threshold points to threshold just below or equal to usage.
@@ -5468,15 +5412,15 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
 
 	mutex_lock(&memcg->thresholds_lock);
 
-	if (type == _MEM)
+	if (type == _MEM) {
 		thresholds = &memcg->thresholds;
-	else if (type == _MEMSWAP)
+		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+	} else if (type == _MEMSWAP) {
 		thresholds = &memcg->memsw_thresholds;
-	else
+		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+	} else
 		BUG();
 
-	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
-
 	/* Check if a threshold crossed before adding a new one */
 	if (thresholds->primary)
 		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
@@ -5556,18 +5500,19 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
 	int i, j, size;
 
 	mutex_lock(&memcg->thresholds_lock);
-	if (type == _MEM)
+
+	if (type == _MEM) {
 		thresholds = &memcg->thresholds;
-	else if (type == _MEMSWAP)
+		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
+	} else if (type == _MEMSWAP) {
 		thresholds = &memcg->memsw_thresholds;
-	else
+		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
+	} else
 		BUG();
 
 	if (!thresholds->primary)
 		goto unlock;
 
-	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
-
 	/* Check if a threshold crossed before removing */
 	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
 
@@ -6329,9 +6274,9 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
 		 * core guarantees its existence.
 		 */
 	} else {
-		res_counter_init(&memcg->res, NULL);
-		res_counter_init(&memcg->memsw, NULL);
-		res_counter_init(&memcg->kmem, NULL);
+		res_counter_init(&memcg->res, &root_mem_cgroup->res);
+		res_counter_init(&memcg->memsw, &root_mem_cgroup->memsw);
+		res_counter_init(&memcg->kmem, &root_mem_cgroup->kmem);
 		/*
 		 * Deeper hierachy with use_hierarchy == false doesn't make
 		 * much sense so let cgroup subsystem know about this
@@ -6449,11 +6394,6 @@ static int mem_cgroup_do_precharge(unsigned long count)
 	int batch_count = PRECHARGE_COUNT_AT_ONCE;
 	struct mem_cgroup *memcg = mc.to;
 
-	if (mem_cgroup_is_root(memcg)) {
-		mc.precharge += count;
-		/* we don't need css_get for root */
-		return ret;
-	}
 	/* try to charge at once */
 	if (count > 1) {
 		struct res_counter *dummy;
@@ -6769,21 +6709,18 @@ static void __mem_cgroup_clear_mc(void)
 	/* we must fixup refcnts and charges */
 	if (mc.moved_swap) {
 		/* uncharge swap account from the old cgroup */
-		if (!mem_cgroup_is_root(mc.from))
-			res_counter_uncharge(&mc.from->memsw,
-						PAGE_SIZE * mc.moved_swap);
+		res_counter_uncharge(&mc.from->memsw,
+				     PAGE_SIZE * mc.moved_swap);
 
 		for (i = 0; i < mc.moved_swap; i++)
 			css_put(&mc.from->css);
 
-		if (!mem_cgroup_is_root(mc.to)) {
-			/*
-			 * we charged both to->res and to->memsw, so we should
-			 * uncharge to->res.
-			 */
-			res_counter_uncharge(&mc.to->res,
-						PAGE_SIZE * mc.moved_swap);
-		}
+		/*
+		 * we charged both to->res and to->memsw, so we should
+		 * uncharge to->res.
+		 */
+		res_counter_uncharge(&mc.to->res,
+				     PAGE_SIZE * mc.moved_swap);
 		/* we've already done css_get(mc.to) */
 		mc.moved_swap = 0;
 	}
-- 
1.9.3

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Re: [patch 06/10] mm: memcontrol: use root_mem_cgroup res_counter

[Michal Hocko]

On Thu 29-05-14 12:15:58, Johannes Weiner wrote:
> Due to an old optimization to keep expensive res_counter changes at a
> minimum, the root_mem_cgroup res_counter is never charged; there is no
> limit at that level anyway, and any statistics can be generated on
> demand by summing up the counters of all other cgroups.
> 
> However, with per-cpu charge caches, res_counter operations do not
> even show up in profiles anymore, so this optimization is no longer
> necessary.
> 
> Remove it to simplify the code.
> 
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

OK, I like the resulting code much more.

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/memcontrol.c | 149 ++++++++++++++++----------------------------------------
>  1 file changed, 43 insertions(+), 106 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 184e67cce4e4..84195a80068c 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2573,9 +2573,8 @@ static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
>  	unsigned long nr_reclaimed;
>  	unsigned long flags = 0;
>  	unsigned long long size;
> +	int ret = 0;
>  
> -	if (mem_cgroup_is_root(memcg))
> -		goto done;
>  retry:
>  	if (consume_stock(memcg, nr_pages))
>  		goto done;
> @@ -2656,13 +2655,15 @@ nomem:
>  	if (!(gfp_mask & __GFP_NOFAIL))
>  		return -ENOMEM;
>  bypass:
> -	return -EINTR;
> +	memcg = root_mem_cgroup;
> +	ret = -EINTR;
> +	goto retry;
>  
>  done_restock:
>  	if (batch > nr_pages)
>  		refill_stock(memcg, batch - nr_pages);
>  done:
> -	return 0;
> +	return ret;
>  }
>  
>  /**
> @@ -2702,13 +2703,11 @@ static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
>  static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
>  				       unsigned int nr_pages)
>  {
> -	if (!mem_cgroup_is_root(memcg)) {
> -		unsigned long bytes = nr_pages * PAGE_SIZE;
> +	unsigned long bytes = nr_pages * PAGE_SIZE;
>  
> -		res_counter_uncharge(&memcg->res, bytes);
> -		if (do_swap_account)
> -			res_counter_uncharge(&memcg->memsw, bytes);
> -	}
> +	res_counter_uncharge(&memcg->res, bytes);
> +	if (do_swap_account)
> +		res_counter_uncharge(&memcg->memsw, bytes);
>  }
>  
>  /*
> @@ -2720,9 +2719,6 @@ static void __mem_cgroup_cancel_local_charge(struct mem_cgroup *memcg,
>  {
>  	unsigned long bytes = nr_pages * PAGE_SIZE;
>  
> -	if (mem_cgroup_is_root(memcg))
> -		return;
> -
>  	res_counter_uncharge_until(&memcg->res, memcg->res.parent, bytes);
>  	if (do_swap_account)
>  		res_counter_uncharge_until(&memcg->memsw,
> @@ -3997,7 +3993,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
>  	 * replacement page, so leave it alone when phasing out the
>  	 * page that is unused after the migration.
>  	 */
> -	if (!end_migration && !mem_cgroup_is_root(memcg))
> +	if (!end_migration)
>  		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
>  
>  	return memcg;
> @@ -4130,8 +4126,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent)
>  		 * We uncharge this because swap is freed.  This memcg can
>  		 * be obsolete one. We avoid calling css_tryget_online().
>  		 */
> -		if (!mem_cgroup_is_root(memcg))
> -			res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
> +		res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
>  		mem_cgroup_swap_statistics(memcg, false);
>  		css_put(&memcg->css);
>  	}
> @@ -4825,78 +4820,24 @@ out:
>  	return retval;
>  }
>  
> -
> -static unsigned long mem_cgroup_recursive_stat(struct mem_cgroup *memcg,
> -					       enum mem_cgroup_stat_index idx)
> -{
> -	struct mem_cgroup *iter;
> -	long val = 0;
> -
> -	/* Per-cpu values can be negative, use a signed accumulator */
> -	for_each_mem_cgroup_tree(iter, memcg)
> -		val += mem_cgroup_read_stat(iter, idx);
> -
> -	if (val < 0) /* race ? */
> -		val = 0;
> -	return val;
> -}
> -
> -static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap)
> -{
> -	u64 val;
> -
> -	if (!mem_cgroup_is_root(memcg)) {
> -		if (!swap)
> -			return res_counter_read_u64(&memcg->res, RES_USAGE);
> -		else
> -			return res_counter_read_u64(&memcg->memsw, RES_USAGE);
> -	}
> -
> -	/*
> -	 * Transparent hugepages are still accounted for in MEM_CGROUP_STAT_RSS
> -	 * as well as in MEM_CGROUP_STAT_RSS_HUGE.
> -	 */
> -	val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE);
> -	val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS);
> -
> -	if (swap)
> -		val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_SWAP);
> -
> -	return val << PAGE_SHIFT;
> -}
> -
>  static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
> -				   struct cftype *cft)
> +			       struct cftype *cft)
>  {
>  	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
> -	u64 val;
> -	int name;
> -	enum res_type type;
> -
> -	type = MEMFILE_TYPE(cft->private);
> -	name = MEMFILE_ATTR(cft->private);
> +	enum res_type type = MEMFILE_TYPE(cft->private);
> +	int name = MEMFILE_ATTR(cft->private);
>  
>  	switch (type) {
>  	case _MEM:
> -		if (name == RES_USAGE)
> -			val = mem_cgroup_usage(memcg, false);
> -		else
> -			val = res_counter_read_u64(&memcg->res, name);
> -		break;
> +		return res_counter_read_u64(&memcg->res, name);
>  	case _MEMSWAP:
> -		if (name == RES_USAGE)
> -			val = mem_cgroup_usage(memcg, true);
> -		else
> -			val = res_counter_read_u64(&memcg->memsw, name);
> -		break;
> +		return res_counter_read_u64(&memcg->memsw, name);
>  	case _KMEM:
> -		val = res_counter_read_u64(&memcg->kmem, name);
> +		return res_counter_read_u64(&memcg->kmem, name);
>  		break;
>  	default:
>  		BUG();
>  	}
> -
> -	return val;
>  }
>  
>  #ifdef CONFIG_MEMCG_KMEM
> @@ -5376,7 +5317,10 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
>  	if (!t)
>  		goto unlock;
>  
> -	usage = mem_cgroup_usage(memcg, swap);
> +	if (!swap)
> +		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
> +	else
> +		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
>  
>  	/*
>  	 * current_threshold points to threshold just below or equal to usage.
> @@ -5468,15 +5412,15 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
>  
>  	mutex_lock(&memcg->thresholds_lock);
>  
> -	if (type == _MEM)
> +	if (type == _MEM) {
>  		thresholds = &memcg->thresholds;
> -	else if (type == _MEMSWAP)
> +		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
> +	} else if (type == _MEMSWAP) {
>  		thresholds = &memcg->memsw_thresholds;
> -	else
> +		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
> +	} else
>  		BUG();
>  
> -	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
> -
>  	/* Check if a threshold crossed before adding a new one */
>  	if (thresholds->primary)
>  		__mem_cgroup_threshold(memcg, type == _MEMSWAP);
> @@ -5556,18 +5500,19 @@ static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
>  	int i, j, size;
>  
>  	mutex_lock(&memcg->thresholds_lock);
> -	if (type == _MEM)
> +
> +	if (type == _MEM) {
>  		thresholds = &memcg->thresholds;
> -	else if (type == _MEMSWAP)
> +		usage = res_counter_read_u64(&memcg->res, RES_USAGE);
> +	} else if (type == _MEMSWAP) {
>  		thresholds = &memcg->memsw_thresholds;
> -	else
> +		usage = res_counter_read_u64(&memcg->memsw, RES_USAGE);
> +	} else
>  		BUG();
>  
>  	if (!thresholds->primary)
>  		goto unlock;
>  
> -	usage = mem_cgroup_usage(memcg, type == _MEMSWAP);
> -
>  	/* Check if a threshold crossed before removing */
>  	__mem_cgroup_threshold(memcg, type == _MEMSWAP);
>  
> @@ -6329,9 +6274,9 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
>  		 * core guarantees its existence.
>  		 */
>  	} else {
> -		res_counter_init(&memcg->res, NULL);
> -		res_counter_init(&memcg->memsw, NULL);
> -		res_counter_init(&memcg->kmem, NULL);
> +		res_counter_init(&memcg->res, &root_mem_cgroup->res);
> +		res_counter_init(&memcg->memsw, &root_mem_cgroup->memsw);
> +		res_counter_init(&memcg->kmem, &root_mem_cgroup->kmem);
>  		/*
>  		 * Deeper hierachy with use_hierarchy == false doesn't make
>  		 * much sense so let cgroup subsystem know about this
> @@ -6449,11 +6394,6 @@ static int mem_cgroup_do_precharge(unsigned long count)
>  	int batch_count = PRECHARGE_COUNT_AT_ONCE;
>  	struct mem_cgroup *memcg = mc.to;
>  
> -	if (mem_cgroup_is_root(memcg)) {
> -		mc.precharge += count;
> -		/* we don't need css_get for root */
> -		return ret;
> -	}
>  	/* try to charge at once */
>  	if (count > 1) {
>  		struct res_counter *dummy;
> @@ -6769,21 +6709,18 @@ static void __mem_cgroup_clear_mc(void)
>  	/* we must fixup refcnts and charges */
>  	if (mc.moved_swap) {
>  		/* uncharge swap account from the old cgroup */
> -		if (!mem_cgroup_is_root(mc.from))
> -			res_counter_uncharge(&mc.from->memsw,
> -						PAGE_SIZE * mc.moved_swap);
> +		res_counter_uncharge(&mc.from->memsw,
> +				     PAGE_SIZE * mc.moved_swap);
>  
>  		for (i = 0; i < mc.moved_swap; i++)
>  			css_put(&mc.from->css);
>  
> -		if (!mem_cgroup_is_root(mc.to)) {
> -			/*
> -			 * we charged both to->res and to->memsw, so we should
> -			 * uncharge to->res.
> -			 */
> -			res_counter_uncharge(&mc.to->res,
> -						PAGE_SIZE * mc.moved_swap);
> -		}
> +		/*
> +		 * we charged both to->res and to->memsw, so we should
> +		 * uncharge to->res.
> +		 */
> +		res_counter_uncharge(&mc.to->res,
> +				     PAGE_SIZE * mc.moved_swap);
>  		/* we've already done css_get(mc.to) */
>  		mc.moved_swap = 0;
>  	}
> -- 
> 1.9.3
> 

-- 
Michal Hocko
SUSE Labs

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[patch 07/10] mm: memcontrol: remove ordering between pc->mem_cgroup and PageCgroupUsed

[Johannes Weiner]

There is a write barrier between setting pc->mem_cgroup and
PageCgroupUsed, which was added to allow LRU operations to lookup the
memcg LRU list of a page without acquiring the page_cgroup lock.

But ever since 38c5d72f3ebe ("memcg: simplify LRU handling by new
rule"), pages are ensured to be off-LRU while charging, so nobody else
is changing LRU state while pc->mem_cgroup is being written, and there
are no read barriers anymore.

Remove the unnecessary write barrier.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
---
 mm/memcontrol.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 84195a80068c..f71eec597001 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2842,14 +2842,6 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
 	}
 
 	pc->mem_cgroup = memcg;
-	/*
-	 * We access a page_cgroup asynchronously without lock_page_cgroup().
-	 * Especially when a page_cgroup is taken from a page, pc->mem_cgroup
-	 * is accessed after testing USED bit. To make pc->mem_cgroup visible
-	 * before USED bit, we need memory barrier here.
-	 * See mem_cgroup_add_lru_list(), etc.
-	 */
-	smp_wmb();
 	SetPageCgroupUsed(pc);
 
 	if (lrucare) {
@@ -3531,7 +3523,6 @@ void mem_cgroup_split_huge_fixup(struct page *head)
 	for (i = 1; i < HPAGE_PMD_NR; i++) {
 		pc = head_pc + i;
 		pc->mem_cgroup = memcg;
-		smp_wmb();/* see __commit_charge() */
 		pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
 	}
 	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
-- 
1.9.3

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[patch 08/10] mm: memcontrol: do not acquire page_cgroup lock for kmem pages

[Johannes Weiner]

Kmem page charging and uncharging is serialized by means of exclusive
access to the page.  Do not take the page_cgroup lock and don't set
pc->flags atomically.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
---
 mm/memcontrol.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f71eec597001..cd024dfb039a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3455,12 +3455,13 @@ void __memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg,
 		memcg_uncharge_kmem(memcg, PAGE_SIZE << order);
 		return;
 	}
-
+	/*
+	 * The page is freshly allocated and not visible to any
+	 * outside callers yet.  Set up pc non-atomically.
+	 */
 	pc = lookup_page_cgroup(page);
-	lock_page_cgroup(pc);
 	pc->mem_cgroup = memcg;
-	SetPageCgroupUsed(pc);
-	unlock_page_cgroup(pc);
+	pc->flags = PCG_USED;
 }
 
 void __memcg_kmem_uncharge_pages(struct page *page, int order)
@@ -3470,19 +3471,11 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order)
 
 
 	pc = lookup_page_cgroup(page);
-	/*
-	 * Fast unlocked return. Theoretically might have changed, have to
-	 * check again after locking.
-	 */
 	if (!PageCgroupUsed(pc))
 		return;
 
-	lock_page_cgroup(pc);
-	if (PageCgroupUsed(pc)) {
-		memcg = pc->mem_cgroup;
-		ClearPageCgroupUsed(pc);
-	}
-	unlock_page_cgroup(pc);
+	memcg = pc->mem_cgroup;
+	pc->flags = 0;
 
 	/*
 	 * We trust that only if there is a memcg associated with the page, it
-- 
1.9.3

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[patch 09/10] mm: memcontrol: rewrite charge API

[Johannes Weiner]

The memcg charge API charges pages before they are rmapped - i.e. have
an actual "type" - and so every callsite needs its own set of charge
and uncharge functions to know what type is being operated on.  Worse,
uncharge has to happen from a context that is still type-specific,
rather than at the end of the page's lifetime with exclusive access,
and so requires a lot of synchronization.

Rewrite the charge API to provide a generic set of try_charge(),
commit_charge() and cancel_charge() transaction operations, much like
what's currently done for swap-in:

  mem_cgroup_try_charge() attempts to reserve a charge, reclaiming
  pages from the memcg if necessary.

  mem_cgroup_commit_charge() commits the page to the charge once it
  has a valid page->mapping and PageAnon() reliably tells the type.

  mem_cgroup_cancel_charge() aborts the transaction.

This reduces the charge API and enables subsequent patches to
drastically simplify uncharging.

As pages need to be committed after rmap is established but before
they are added to the LRU, page_add_new_anon_rmap() must stop doing
LRU additions again.  Revive lru_cache_add_active_or_unevictable().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 Documentation/cgroups/memcg_test.txt |  32 +--
 include/linux/memcontrol.h           |  53 ++---
 include/linux/swap.h                 |   3 +
 kernel/events/uprobes.c              |   1 +
 mm/filemap.c                         |   9 +-
 mm/huge_memory.c                     |  55 +++--
 mm/memcontrol.c                      | 418 ++++++++++++++---------------------
 mm/memory.c                          |  41 ++--
 mm/rmap.c                            |  19 --
 mm/shmem.c                           |  24 +-
 mm/swap.c                            |  34 +++
 mm/swapfile.c                        |  14 +-
 12 files changed, 316 insertions(+), 387 deletions(-)

diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index 80ac454704b8..bcf750d3cecd 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/Documentation/cgroups/memcg_test.txt
@@ -24,24 +24,7 @@ Please note that implementation details can be changed.
 
    a page/swp_entry may be charged (usage += PAGE_SIZE) at
 
-	mem_cgroup_charge_anon()
-	  Called at new page fault and Copy-On-Write.
-
-	mem_cgroup_try_charge_swapin()
-	  Called at do_swap_page() (page fault on swap entry) and swapoff.
-	  Followed by charge-commit-cancel protocol. (With swap accounting)
-	  At commit, a charge recorded in swap_cgroup is removed.
-
-	mem_cgroup_charge_file()
-	  Called at add_to_page_cache()
-
-	mem_cgroup_cache_charge_swapin()
-	  Called at shmem's swapin.
-
-	mem_cgroup_prepare_migration()
-	  Called before migration. "extra" charge is done and followed by
-	  charge-commit-cancel protocol.
-	  At commit, charge against oldpage or newpage will be committed.
+	mem_cgroup_try_charge()
 
 2. Uncharge
   a page/swp_entry may be uncharged (usage -= PAGE_SIZE) by
@@ -69,19 +52,14 @@ Please note that implementation details can be changed.
 	to new page is committed. At failure, charge to old page is committed.
 
 3. charge-commit-cancel
-	In some case, we can't know this "charge" is valid or not at charging
-	(because of races).
-	To handle such case, there are charge-commit-cancel functions.
-		mem_cgroup_try_charge_XXX
-		mem_cgroup_commit_charge_XXX
-		mem_cgroup_cancel_charge_XXX
-	these are used in swap-in and migration.
+	Memcg pages are charged in two steps:
+		mem_cgroup_try_charge()
+		mem_cgroup_commit_charge() or mem_cgroup_cancel_charge()
 
 	At try_charge(), there are no flags to say "this page is charged".
 	at this point, usage += PAGE_SIZE.
 
-	At commit(), the function checks the page should be charged or not
-	and set flags or avoid charging.(usage -= PAGE_SIZE)
+	At commit(), the page is associated with the memcg.
 
 	At cancel(), simply usage -= PAGE_SIZE.
 
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a5cf853129ec..bd2cc35babe0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -54,28 +54,11 @@ struct mem_cgroup_reclaim_cookie {
 };
 
 #ifdef CONFIG_MEMCG
-/*
- * All "charge" functions with gfp_mask should use GFP_KERNEL or
- * (gfp_mask & GFP_RECLAIM_MASK). In current implementatin, memcg doesn't
- * alloc memory but reclaims memory from all available zones. So, "where I want
- * memory from" bits of gfp_mask has no meaning. So any bits of that field is
- * available but adding a rule is better. charge functions' gfp_mask should
- * be set to GFP_KERNEL or gfp_mask & GFP_RECLAIM_MASK for avoiding ambiguous
- * codes.
- * (Of course, if memcg does memory allocation in future, GFP_KERNEL is sane.)
- */
-
-extern int mem_cgroup_charge_anon(struct page *page, struct mm_struct *mm,
-				gfp_t gfp_mask);
-/* for swap handling */
-extern int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
-		struct page *page, gfp_t mask, struct mem_cgroup **memcgp);
-extern void mem_cgroup_commit_charge_swapin(struct page *page,
-					struct mem_cgroup *memcg);
-extern void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg);
-
-extern int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
-					gfp_t gfp_mask);
+int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
+			  gfp_t gfp_mask, struct mem_cgroup **memcgp);
+void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
+			      bool lrucare);
+void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg);
 
 struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
 struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
@@ -237,30 +220,22 @@ void mem_cgroup_print_bad_page(struct page *page);
 #else /* CONFIG_MEMCG */
 struct mem_cgroup;
 
-static inline int mem_cgroup_charge_anon(struct page *page,
-					struct mm_struct *mm, gfp_t gfp_mask)
-{
-	return 0;
-}
-
-static inline int mem_cgroup_charge_file(struct page *page,
-					struct mm_struct *mm, gfp_t gfp_mask)
-{
-	return 0;
-}
-
-static inline int mem_cgroup_try_charge_swapin(struct mm_struct *mm,
-		struct page *page, gfp_t gfp_mask, struct mem_cgroup **memcgp)
+static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
+					gfp_t gfp_mask,
+					struct mem_cgroup **memcgp)
 {
+	*memcgp = NULL;
 	return 0;
 }
 
-static inline void mem_cgroup_commit_charge_swapin(struct page *page,
-					  struct mem_cgroup *memcg)
+static inline void mem_cgroup_commit_charge(struct page *page,
+					    struct mem_cgroup *memcg,
+					    bool lrucare)
 {
 }
 
-static inline void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
+static inline void mem_cgroup_cancel_charge(struct page *page,
+					    struct mem_cgroup *memcg)
 {
 }
 
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 4bdbee80eede..290905133078 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -321,6 +321,9 @@ extern void swap_setup(void);
 
 extern void add_page_to_unevictable_list(struct page *page);
 
+extern void lru_cache_add_active_or_unevictable(struct page *page,
+						struct vm_area_struct *vma);
+
 /* linux/mm/vmscan.c */
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 					gfp_t gfp_mask, nodemask_t *mask);
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 7f2d4dae54a2..d68e014321f5 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -178,6 +178,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
 
 	get_page(kpage);
 	page_add_new_anon_rmap(kpage, vma, addr);
+	lru_cache_add_active_or_unevictable(kpage, vma);
 
 	if (!PageAnon(page)) {
 		dec_mm_counter(mm, MM_FILEPAGES);
diff --git a/mm/filemap.c b/mm/filemap.c
index dafb06f70a09..114cd89c1cc2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -560,19 +560,19 @@ static int __add_to_page_cache_locked(struct page *page,
 				      pgoff_t offset, gfp_t gfp_mask,
 				      void **shadowp)
 {
+	struct mem_cgroup *memcg;
 	int error;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 	VM_BUG_ON_PAGE(PageSwapBacked(page), page);
 
-	error = mem_cgroup_charge_file(page, current->mm,
-					gfp_mask & GFP_RECLAIM_MASK);
+	error = mem_cgroup_try_charge(page, current->mm, gfp_mask, &memcg);
 	if (error)
 		return error;
 
 	error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM);
 	if (error) {
-		mem_cgroup_uncharge_cache_page(page);
+		mem_cgroup_cancel_charge(page, memcg);
 		return error;
 	}
 
@@ -587,13 +587,14 @@ static int __add_to_page_cache_locked(struct page *page,
 		goto err_insert;
 	__inc_zone_page_state(page, NR_FILE_PAGES);
 	spin_unlock_irq(&mapping->tree_lock);
+	mem_cgroup_commit_charge(page, memcg, false);
 	trace_mm_filemap_add_to_page_cache(page);
 	return 0;
 err_insert:
 	page->mapping = NULL;
 	/* Leave page->index set: truncation relies upon it */
 	spin_unlock_irq(&mapping->tree_lock);
-	mem_cgroup_uncharge_cache_page(page);
+	mem_cgroup_cancel_charge(page, memcg);
 	page_cache_release(page);
 	return error;
 }
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c5ff461e0253..7acc09d92afb 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -715,13 +715,20 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
 					unsigned long haddr, pmd_t *pmd,
 					struct page *page)
 {
+	struct mem_cgroup *memcg;
 	pgtable_t pgtable;
 	spinlock_t *ptl;
 
 	VM_BUG_ON_PAGE(!PageCompound(page), page);
+
+	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
+		return VM_FAULT_OOM;
+
 	pgtable = pte_alloc_one(mm, haddr);
-	if (unlikely(!pgtable))
+	if (unlikely(!pgtable)) {
+		mem_cgroup_cancel_charge(page, memcg);
 		return VM_FAULT_OOM;
+	}
 
 	clear_huge_page(page, haddr, HPAGE_PMD_NR);
 	/*
@@ -734,7 +741,7 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
 	ptl = pmd_lock(mm, pmd);
 	if (unlikely(!pmd_none(*pmd))) {
 		spin_unlock(ptl);
-		mem_cgroup_uncharge_page(page);
+		mem_cgroup_cancel_charge(page, memcg);
 		put_page(page);
 		pte_free(mm, pgtable);
 	} else {
@@ -742,6 +749,8 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
 		entry = mk_huge_pmd(page, vma->vm_page_prot);
 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 		page_add_new_anon_rmap(page, vma, haddr);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
 		pgtable_trans_huge_deposit(mm, pmd, pgtable);
 		set_pmd_at(mm, haddr, pmd, entry);
 		add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
@@ -827,13 +836,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		count_vm_event(THP_FAULT_FALLBACK);
 		return VM_FAULT_FALLBACK;
 	}
-	if (unlikely(mem_cgroup_charge_anon(page, mm, GFP_KERNEL))) {
-		put_page(page);
-		count_vm_event(THP_FAULT_FALLBACK);
-		return VM_FAULT_FALLBACK;
-	}
 	if (unlikely(__do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page))) {
-		mem_cgroup_uncharge_page(page);
 		put_page(page);
 		count_vm_event(THP_FAULT_FALLBACK);
 		return VM_FAULT_FALLBACK;
@@ -948,6 +951,7 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 					struct page *page,
 					unsigned long haddr)
 {
+	struct mem_cgroup *memcg;
 	spinlock_t *ptl;
 	pgtable_t pgtable;
 	pmd_t _pmd;
@@ -968,20 +972,21 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 					       __GFP_OTHER_NODE,
 					       vma, address, page_to_nid(page));
 		if (unlikely(!pages[i] ||
-			     mem_cgroup_charge_anon(pages[i], mm,
-						       GFP_KERNEL))) {
+			     mem_cgroup_try_charge(pages[i], mm, GFP_KERNEL,
+						   &memcg))) {
 			if (pages[i])
 				put_page(pages[i]);
-			mem_cgroup_uncharge_start();
 			while (--i >= 0) {
-				mem_cgroup_uncharge_page(pages[i]);
+				memcg = (void *)page_private(pages[i]);
+				set_page_private(pages[i], 0);
+				mem_cgroup_cancel_charge(pages[i], memcg);
 				put_page(pages[i]);
 			}
-			mem_cgroup_uncharge_end();
 			kfree(pages);
 			ret |= VM_FAULT_OOM;
 			goto out;
 		}
+		set_page_private(pages[i], (unsigned long)memcg);
 	}
 
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
@@ -1010,7 +1015,11 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 		pte_t *pte, entry;
 		entry = mk_pte(pages[i], vma->vm_page_prot);
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		memcg = (void *)page_private(pages[i]);
+		set_page_private(pages[i], 0);
 		page_add_new_anon_rmap(pages[i], vma, haddr);
+		mem_cgroup_commit_charge(pages[i], memcg, false);
+		lru_cache_add_active_or_unevictable(pages[i], vma);
 		pte = pte_offset_map(&_pmd, haddr);
 		VM_BUG_ON(!pte_none(*pte));
 		set_pte_at(mm, haddr, pte, entry);
@@ -1034,12 +1043,12 @@ out:
 out_free_pages:
 	spin_unlock(ptl);
 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
-	mem_cgroup_uncharge_start();
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
-		mem_cgroup_uncharge_page(pages[i]);
+		memcg = (void *)page_private(pages[i]);
+		set_page_private(pages[i], 0);
+		mem_cgroup_cancel_charge(pages[i], memcg);
 		put_page(pages[i]);
 	}
-	mem_cgroup_uncharge_end();
 	kfree(pages);
 	goto out;
 }
@@ -1050,6 +1059,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	spinlock_t *ptl;
 	int ret = 0;
 	struct page *page = NULL, *new_page;
+	struct mem_cgroup *memcg;
 	unsigned long haddr;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
@@ -1101,7 +1111,7 @@ alloc:
 		goto out;
 	}
 
-	if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))) {
+	if (unlikely(mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))) {
 		put_page(new_page);
 		if (page) {
 			split_huge_page(page);
@@ -1130,7 +1140,7 @@ alloc:
 		put_page(page);
 	if (unlikely(!pmd_same(*pmd, orig_pmd))) {
 		spin_unlock(ptl);
-		mem_cgroup_uncharge_page(new_page);
+		mem_cgroup_cancel_charge(new_page, memcg);
 		put_page(new_page);
 		goto out_mn;
 	} else {
@@ -1139,6 +1149,8 @@ alloc:
 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 		pmdp_clear_flush(vma, haddr, pmd);
 		page_add_new_anon_rmap(new_page, vma, haddr);
+		mem_cgroup_commit_charge(new_page, memcg, false);
+		lru_cache_add_active_or_unevictable(new_page, vma);
 		set_pmd_at(mm, haddr, pmd, entry);
 		update_mmu_cache_pmd(vma, address, pmd);
 		if (!page) {
@@ -2358,6 +2370,7 @@ static void collapse_huge_page(struct mm_struct *mm,
 	spinlock_t *pmd_ptl, *pte_ptl;
 	int isolated;
 	unsigned long hstart, hend;
+	struct mem_cgroup *memcg;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
 
@@ -2368,7 +2381,7 @@ static void collapse_huge_page(struct mm_struct *mm,
 	if (!new_page)
 		return;
 
-	if (unlikely(mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)))
+	if (unlikely(mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)))
 		return;
 
 	/*
@@ -2457,6 +2470,8 @@ static void collapse_huge_page(struct mm_struct *mm,
 	spin_lock(pmd_ptl);
 	BUG_ON(!pmd_none(*pmd));
 	page_add_new_anon_rmap(new_page, vma, address);
+	mem_cgroup_commit_charge(new_page, memcg, false);
+	lru_cache_add_active_or_unevictable(new_page, vma);
 	pgtable_trans_huge_deposit(mm, pmd, pgtable);
 	set_pmd_at(mm, address, pmd, _pmd);
 	update_mmu_cache_pmd(vma, address, pmd);
@@ -2470,7 +2485,7 @@ out_up_write:
 	return;
 
 out:
-	mem_cgroup_uncharge_page(new_page);
+	mem_cgroup_cancel_charge(new_page, memcg);
 	goto out_up_write;
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index cd024dfb039a..9458c9e3e08c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2552,19 +2552,8 @@ static int memcg_cpu_hotplug_callback(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
-/**
- * mem_cgroup_try_charge - try charging a memcg
- * @memcg: memcg to charge
- * @nr_pages: number of pages to charge
- * @oom: trigger OOM if reclaim fails
- *
- * Returns 0 if @memcg was charged successfully, -EINTR if the charge
- * was bypassed to root_mem_cgroup, and -ENOMEM if the charge failed.
- */
-static int mem_cgroup_try_charge(struct mem_cgroup *memcg,
-				 gfp_t gfp_mask,
-				 unsigned int nr_pages,
-				 bool oom)
+static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
+		      unsigned int nr_pages, bool oom)
 {
 	unsigned int batch = max(CHARGE_BATCH, nr_pages);
 	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
@@ -2666,42 +2655,7 @@ done:
 	return ret;
 }
 
-/**
- * mem_cgroup_try_charge_mm - try charging a mm
- * @mm: mm_struct to charge
- * @nr_pages: number of pages to charge
- * @oom: trigger OOM if reclaim fails
- *
- * Returns the charged mem_cgroup associated with the given mm_struct or
- * NULL the charge failed.
- */
-static struct mem_cgroup *mem_cgroup_try_charge_mm(struct mm_struct *mm,
-				 gfp_t gfp_mask,
-				 unsigned int nr_pages,
-				 bool oom)
-
-{
-	struct mem_cgroup *memcg;
-	int ret;
-
-	memcg = get_mem_cgroup_from_mm(mm);
-	ret = mem_cgroup_try_charge(memcg, gfp_mask, nr_pages, oom);
-	css_put(&memcg->css);
-	if (ret == -EINTR)
-		memcg = root_mem_cgroup;
-	else if (ret)
-		memcg = NULL;
-
-	return memcg;
-}
-
-/*
- * Somemtimes we have to undo a charge we got by try_charge().
- * This function is for that and do uncharge, put css's refcnt.
- * gotten by try_charge().
- */
-static void __mem_cgroup_cancel_charge(struct mem_cgroup *memcg,
-				       unsigned int nr_pages)
+static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 {
 	unsigned long bytes = nr_pages * PAGE_SIZE;
 
@@ -2807,17 +2761,13 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
 	return memcg;
 }
 
-static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
-				       struct page *page,
-				       unsigned int nr_pages,
-				       enum charge_type ctype,
-				       bool lrucare)
+static void commit_charge(struct page *page, struct mem_cgroup *memcg,
+			  unsigned int nr_pages, bool anon, bool lrucare)
 {
 	struct page_cgroup *pc = lookup_page_cgroup(page);
 	struct zone *uninitialized_var(zone);
 	struct lruvec *lruvec;
 	bool was_on_lru = false;
-	bool anon;
 
 	lock_page_cgroup(pc);
 	VM_BUG_ON_PAGE(PageCgroupUsed(pc), page);
@@ -2854,11 +2804,6 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
 		spin_unlock_irq(&zone->lru_lock);
 	}
 
-	if (ctype == MEM_CGROUP_CHARGE_TYPE_ANON)
-		anon = true;
-	else
-		anon = false;
-
 	mem_cgroup_charge_statistics(memcg, page, anon, nr_pages);
 	unlock_page_cgroup(pc);
 
@@ -2929,22 +2874,21 @@ static int memcg_charge_kmem(struct mem_cgroup *memcg, gfp_t gfp, u64 size)
 	if (ret)
 		return ret;
 
-	ret = mem_cgroup_try_charge(memcg, gfp, size >> PAGE_SHIFT,
-				    oom_gfp_allowed(gfp));
+	ret = try_charge(memcg, gfp, size >> PAGE_SHIFT, oom_gfp_allowed(gfp));
 	if (ret == -EINTR)  {
 		/*
-		 * mem_cgroup_try_charge() chosed to bypass to root due to
-		 * OOM kill or fatal signal.  Since our only options are to
-		 * either fail the allocation or charge it to this cgroup, do
-		 * it as a temporary condition. But we can't fail. From a
-		 * kmem/slab perspective, the cache has already been selected,
-		 * by mem_cgroup_kmem_get_cache(), so it is too late to change
+		 * try_charge() chose to bypass to root due to OOM kill or
+		 * fatal signal.  Since our only options are to either fail
+		 * the allocation or charge it to this cgroup, do it as a
+		 * temporary condition. But we can't fail. From a kmem/slab
+		 * perspective, the cache has already been selected, by
+		 * mem_cgroup_kmem_get_cache(), so it is too late to change
 		 * our minds.
 		 *
 		 * This condition will only trigger if the task entered
-		 * memcg_charge_kmem in a sane state, but was OOM-killed during
-		 * mem_cgroup_try_charge() above. Tasks that were already
-		 * dying when the allocation triggers should have been already
+		 * memcg_charge_kmem in a sane state, but was OOM-killed
+		 * during try_charge() above. Tasks that were already dying
+		 * when the allocation triggers should have been already
 		 * directed to the root cgroup in memcontrol.h
 		 */
 		res_counter_charge_nofail(&memcg->res, size, &fail_res);
@@ -3666,170 +3610,6 @@ out:
 	return ret;
 }
 
-int mem_cgroup_charge_anon(struct page *page,
-			      struct mm_struct *mm, gfp_t gfp_mask)
-{
-	unsigned int nr_pages = 1;
-	struct mem_cgroup *memcg;
-	bool oom = true;
-
-	if (mem_cgroup_disabled())
-		return 0;
-
-	VM_BUG_ON_PAGE(page_mapped(page), page);
-	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
-	VM_BUG_ON(!mm);
-
-	if (PageTransHuge(page)) {
-		nr_pages <<= compound_order(page);
-		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
-		/*
-		 * Never OOM-kill a process for a huge page.  The
-		 * fault handler will fall back to regular pages.
-		 */
-		oom = false;
-	}
-
-	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, nr_pages, oom);
-	if (!memcg)
-		return -ENOMEM;
-	__mem_cgroup_commit_charge(memcg, page, nr_pages,
-				   MEM_CGROUP_CHARGE_TYPE_ANON, false);
-	return 0;
-}
-
-/*
- * While swap-in, try_charge -> commit or cancel, the page is locked.
- * And when try_charge() successfully returns, one refcnt to memcg without
- * struct page_cgroup is acquired. This refcnt will be consumed by
- * "commit()" or removed by "cancel()"
- */
-static int __mem_cgroup_try_charge_swapin(struct mm_struct *mm,
-					  struct page *page,
-					  gfp_t mask,
-					  struct mem_cgroup **memcgp)
-{
-	struct mem_cgroup *memcg = NULL;
-	struct page_cgroup *pc;
-	int ret;
-
-	pc = lookup_page_cgroup(page);
-	/*
-	 * Every swap fault against a single page tries to charge the
-	 * page, bail as early as possible.  shmem_unuse() encounters
-	 * already charged pages, too.  The USED bit is protected by
-	 * the page lock, which serializes swap cache removal, which
-	 * in turn serializes uncharging.
-	 */
-	if (PageCgroupUsed(pc))
-		goto out;
-	if (do_swap_account)
-		memcg = try_get_mem_cgroup_from_page(page);
-	if (!memcg)
-		memcg = get_mem_cgroup_from_mm(mm);
-	ret = mem_cgroup_try_charge(memcg, mask, 1, true);
-	css_put(&memcg->css);
-	if (ret == -EINTR)
-		memcg = root_mem_cgroup;
-	else if (ret)
-		return ret;
-out:
-	*memcgp = memcg;
-	return 0;
-}
-
-int mem_cgroup_try_charge_swapin(struct mm_struct *mm, struct page *page,
-				 gfp_t gfp_mask, struct mem_cgroup **memcgp)
-{
-	if (mem_cgroup_disabled()) {
-		*memcgp = NULL;
-		return 0;
-	}
-	/*
-	 * A racing thread's fault, or swapoff, may have already
-	 * updated the pte, and even removed page from swap cache: in
-	 * those cases unuse_pte()'s pte_same() test will fail; but
-	 * there's also a KSM case which does need to charge the page.
-	 */
-	if (!PageSwapCache(page)) {
-		struct mem_cgroup *memcg;
-
-		memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
-		if (!memcg)
-			return -ENOMEM;
-		*memcgp = memcg;
-		return 0;
-	}
-	return __mem_cgroup_try_charge_swapin(mm, page, gfp_mask, memcgp);
-}
-
-void mem_cgroup_cancel_charge_swapin(struct mem_cgroup *memcg)
-{
-	if (mem_cgroup_disabled())
-		return;
-	if (!memcg)
-		return;
-	__mem_cgroup_cancel_charge(memcg, 1);
-}
-
-static void
-__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,
-					enum charge_type ctype)
-{
-	if (mem_cgroup_disabled())
-		return;
-	if (!memcg)
-		return;
-
-	__mem_cgroup_commit_charge(memcg, page, 1, ctype, true);
-	/*
-	 * Now swap is on-memory. This means this page may be
-	 * counted both as mem and swap....double count.
-	 * Fix it by uncharging from memsw. Basically, this SwapCache is stable
-	 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
-	 * may call delete_from_swap_cache() before reach here.
-	 */
-	if (do_swap_account && PageSwapCache(page)) {
-		swp_entry_t ent = {.val = page_private(page)};
-		mem_cgroup_uncharge_swap(ent);
-	}
-}
-
-void mem_cgroup_commit_charge_swapin(struct page *page,
-				     struct mem_cgroup *memcg)
-{
-	__mem_cgroup_commit_charge_swapin(page, memcg,
-					  MEM_CGROUP_CHARGE_TYPE_ANON);
-}
-
-int mem_cgroup_charge_file(struct page *page, struct mm_struct *mm,
-				gfp_t gfp_mask)
-{
-	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
-	struct mem_cgroup *memcg;
-	int ret;
-
-	if (mem_cgroup_disabled())
-		return 0;
-	if (PageCompound(page))
-		return 0;
-
-	if (PageSwapCache(page)) { /* shmem */
-		ret = __mem_cgroup_try_charge_swapin(mm, page,
-						     gfp_mask, &memcg);
-		if (ret)
-			return ret;
-		__mem_cgroup_commit_charge_swapin(page, memcg, type);
-		return 0;
-	}
-
-	memcg = mem_cgroup_try_charge_mm(mm, gfp_mask, 1, true);
-	if (!memcg)
-		return -ENOMEM;
-	__mem_cgroup_commit_charge(memcg, page, 1, type, false);
-	return 0;
-}
-
 static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
 				   unsigned int nr_pages,
 				   const enum charge_type ctype)
@@ -4176,7 +3956,6 @@ void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
 	struct mem_cgroup *memcg = NULL;
 	unsigned int nr_pages = 1;
 	struct page_cgroup *pc;
-	enum charge_type ctype;
 
 	*memcgp = NULL;
 
@@ -4238,16 +4017,12 @@ void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
 	 * page. In the case new page is migrated but not remapped, new page's
 	 * mapcount will be finally 0 and we call uncharge in end_migration().
 	 */
-	if (PageAnon(page))
-		ctype = MEM_CGROUP_CHARGE_TYPE_ANON;
-	else
-		ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;
 	/*
 	 * The page is committed to the memcg, but it's not actually
 	 * charged to the res_counter since we plan on replacing the
 	 * old one and only one page is going to be left afterwards.
 	 */
-	__mem_cgroup_commit_charge(memcg, newpage, nr_pages, ctype, false);
+	commit_charge(newpage, memcg, nr_pages, PageAnon(page), false);
 }
 
 /* remove redundant charge if migration failed*/
@@ -4306,7 +4081,6 @@ void mem_cgroup_replace_page_cache(struct page *oldpage,
 {
 	struct mem_cgroup *memcg = NULL;
 	struct page_cgroup *pc;
-	enum charge_type type = MEM_CGROUP_CHARGE_TYPE_CACHE;
 
 	if (mem_cgroup_disabled())
 		return;
@@ -4332,7 +4106,7 @@ void mem_cgroup_replace_page_cache(struct page *oldpage,
 	 * the newpage may be on LRU(or pagevec for LRU) already. We lock
 	 * LRU while we overwrite pc->mem_cgroup.
 	 */
-	__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);
+	commit_charge(newpage, memcg, 1, false, true);
 }
 
 #ifdef CONFIG_DEBUG_VM
@@ -6408,7 +6182,7 @@ one_by_one:
 			batch_count = PRECHARGE_COUNT_AT_ONCE;
 			cond_resched();
 		}
-		ret = mem_cgroup_try_charge(memcg, GFP_KERNEL, 1, false);
+		ret = try_charge(memcg, GFP_KERNEL, 1, false);
 		/*
 		 * In case of failure, any residual charges against
 		 * mc.to will be dropped by mem_cgroup_clear_mc()
@@ -6416,7 +6190,7 @@ one_by_one:
 		 * bypassed to root right away or they'll be lost.
 		 */
 		if (ret == -EINTR)
-			__mem_cgroup_cancel_charge(root_mem_cgroup, 1);
+			cancel_charge(root_mem_cgroup, 1);
 		if (ret)
 			return ret;
 		mc.precharge++;
@@ -6679,7 +6453,7 @@ static void __mem_cgroup_clear_mc(void)
 
 	/* we must uncharge all the leftover precharges from mc.to */
 	if (mc.precharge) {
-		__mem_cgroup_cancel_charge(mc.to, mc.precharge);
+		cancel_charge(mc.to, mc.precharge);
 		mc.precharge = 0;
 	}
 	/*
@@ -6687,7 +6461,7 @@ static void __mem_cgroup_clear_mc(void)
 	 * we must uncharge here.
 	 */
 	if (mc.moved_charge) {
-		__mem_cgroup_cancel_charge(mc.from, mc.moved_charge);
+		cancel_charge(mc.from, mc.moved_charge);
 		mc.moved_charge = 0;
 	}
 	/* we must fixup refcnts and charges */
@@ -7001,6 +6775,156 @@ static void __init enable_swap_cgroup(void)
 }
 #endif
 
+/**
+ * mem_cgroup_try_charge - try charging a page
+ * @page: page to charge
+ * @mm: mm context of the victim
+ * @gfp_mask: reclaim mode
+ * @memcgp: charged memcg return
+ *
+ * Try to charge @page to the memcg that @mm belongs to, reclaiming
+ * pages according to @gfp_mask if necessary.
+ *
+ * Returns 0 on success, with *@memcgp pointing to the charged memcg.
+ * Otherwise, an error code is returned.
+ *
+ * After page->mapping has been set up, the caller must finalize the
+ * charge with mem_cgroup_commit_charge().  Or abort the transaction
+ * with mem_cgroup_cancel_charge() in case page instantiation fails.
+ */
+int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
+			  gfp_t gfp_mask, struct mem_cgroup **memcgp)
+{
+	struct mem_cgroup *memcg = NULL;
+	unsigned int nr_pages = 1;
+	bool oom = true;
+	int ret = 0;
+
+	if (mem_cgroup_disabled())
+		goto out;
+
+	if (PageSwapCache(page)) {
+		struct page_cgroup *pc = lookup_page_cgroup(page);
+		/*
+		 * Every swap fault against a single page tries to charge the
+		 * page, bail as early as possible.  shmem_unuse() encounters
+		 * already charged pages, too.  The USED bit is protected by
+		 * the page lock, which serializes swap cache removal, which
+		 * in turn serializes uncharging.
+		 */
+		if (PageCgroupUsed(pc))
+			goto out;
+	}
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+		/*
+		 * Never OOM-kill a process for a huge page.  The
+		 * fault handler will fall back to regular pages.
+		 */
+		oom = false;
+	}
+
+	if (do_swap_account && PageSwapCache(page))
+		memcg = try_get_mem_cgroup_from_page(page);
+	if (!memcg)
+		memcg = get_mem_cgroup_from_mm(mm);
+
+	ret = try_charge(memcg, gfp_mask, nr_pages, oom);
+
+	css_put(&memcg->css);
+
+	if (ret == -EINTR) {
+		memcg = root_mem_cgroup;
+		ret = 0;
+	}
+out:
+	*memcgp = memcg;
+	return ret;
+}
+
+/**
+ * mem_cgroup_commit_charge - commit a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ * @lrucare: page might be on LRU already
+ *
+ * Finalize a charge transaction started by mem_cgroup_try_charge(),
+ * after page->mapping has been set up.  This must happen atomically
+ * as part of the page instantiation, i.e. under the page table lock
+ * for anonymous pages, under the page lock for page and swap cache.
+ *
+ * In addition, the page must not be on the LRU during the commit, to
+ * prevent racing with task migration.  If it might be, use @lrucare.
+ *
+ * Use mem_cgroup_cancel_charge() to cancel the transaction instead.
+ */
+void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
+			      bool lrucare)
+{
+	unsigned int nr_pages = 1;
+
+	VM_BUG_ON_PAGE(!page->mapping, page);
+	VM_BUG_ON_PAGE(PageLRU(page) && !lrucare, page);
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+
+	commit_charge(page, memcg, nr_pages, PageAnon(page), lrucare);
+
+	if (do_swap_account && PageSwapCache(page)) {
+		swp_entry_t entry = { .val = page_private(page) };
+		/*
+		 * The swap entry might not get freed for a long time,
+		 * let's not wait for it.  The page already received a
+		 * memory+swap charge, drop the swap entry duplicate.
+		 */
+		mem_cgroup_uncharge_swap(entry);
+	}
+}
+
+/**
+ * mem_cgroup_cancel_charge - cancel a page charge
+ * @page: page to charge
+ * @memcg: memcg to charge the page to
+ *
+ * Cancel a charge transaction started by mem_cgroup_try_charge().
+ */
+void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
+{
+	unsigned int nr_pages = 1;
+
+	if (mem_cgroup_disabled())
+		return;
+	/*
+	 * Swap faults will attempt to charge the same page multiple
+	 * times.  But reuse_swap_page() might have removed the page
+	 * from swapcache already, so we can't check PageSwapCache().
+	 */
+	if (!memcg)
+		return;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+
+	cancel_charge(memcg, nr_pages);
+}
+
 /*
  * subsys_initcall() for memory controller.
  *
diff --git a/mm/memory.c b/mm/memory.c
index e9a3c0fe368d..3b95ee253c19 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2049,6 +2049,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	struct page *dirty_page = NULL;
 	unsigned long mmun_start = 0;	/* For mmu_notifiers */
 	unsigned long mmun_end = 0;	/* For mmu_notifiers */
+	struct mem_cgroup *memcg;
 
 	old_page = vm_normal_page(vma, address, orig_pte);
 	if (!old_page) {
@@ -2204,7 +2205,7 @@ gotten:
 	}
 	__SetPageUptodate(new_page);
 
-	if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
+	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg))
 		goto oom_free_new;
 
 	mmun_start  = address & PAGE_MASK;
@@ -2234,6 +2235,8 @@ gotten:
 		 */
 		ptep_clear_flush(vma, address, page_table);
 		page_add_new_anon_rmap(new_page, vma, address);
+		mem_cgroup_commit_charge(new_page, memcg, false);
+		lru_cache_add_active_or_unevictable(new_page, vma);
 		/*
 		 * We call the notify macro here because, when using secondary
 		 * mmu page tables (such as kvm shadow page tables), we want the
@@ -2271,7 +2274,7 @@ gotten:
 		new_page = old_page;
 		ret |= VM_FAULT_WRITE;
 	} else
-		mem_cgroup_uncharge_page(new_page);
+		mem_cgroup_cancel_charge(new_page, memcg);
 
 	if (new_page)
 		page_cache_release(new_page);
@@ -2407,10 +2410,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 {
 	spinlock_t *ptl;
 	struct page *page, *swapcache;
+	struct mem_cgroup *memcg;
 	swp_entry_t entry;
 	pte_t pte;
 	int locked;
-	struct mem_cgroup *ptr;
 	int exclusive = 0;
 	int ret = 0;
 
@@ -2486,7 +2489,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		goto out_page;
 	}
 
-	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
+	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) {
 		ret = VM_FAULT_OOM;
 		goto out_page;
 	}
@@ -2511,10 +2514,6 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * while the page is counted on swap but not yet in mapcount i.e.
 	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
 	 * must be called after the swap_free(), or it will never succeed.
-	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
-	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
-	 * in page->private. In this case, a record in swap_cgroup  is silently
-	 * discarded at swap_free().
 	 */
 
 	inc_mm_counter_fast(mm, MM_ANONPAGES);
@@ -2530,12 +2529,14 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (pte_swp_soft_dirty(orig_pte))
 		pte = pte_mksoft_dirty(pte);
 	set_pte_at(mm, address, page_table, pte);
-	if (page == swapcache)
+	if (page == swapcache) {
 		do_page_add_anon_rmap(page, vma, address, exclusive);
-	else /* ksm created a completely new copy */
+		mem_cgroup_commit_charge(page, memcg, true);
+	} else { /* ksm created a completely new copy */
 		page_add_new_anon_rmap(page, vma, address);
-	/* It's better to call commit-charge after rmap is established */
-	mem_cgroup_commit_charge_swapin(page, ptr);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
+	}
 
 	swap_free(entry);
 	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
@@ -2568,7 +2569,7 @@ unlock:
 out:
 	return ret;
 out_nomap:
-	mem_cgroup_cancel_charge_swapin(ptr);
+	mem_cgroup_cancel_charge(page, memcg);
 	pte_unmap_unlock(page_table, ptl);
 out_page:
 	unlock_page(page);
@@ -2624,6 +2625,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		unsigned long address, pte_t *page_table, pmd_t *pmd,
 		unsigned int flags)
 {
+	struct mem_cgroup *memcg;
 	struct page *page;
 	spinlock_t *ptl;
 	pte_t entry;
@@ -2657,7 +2659,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	 */
 	__SetPageUptodate(page);
 
-	if (mem_cgroup_charge_anon(page, mm, GFP_KERNEL))
+	if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg))
 		goto oom_free_page;
 
 	entry = mk_pte(page, vma->vm_page_prot);
@@ -2670,6 +2672,8 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	inc_mm_counter_fast(mm, MM_ANONPAGES);
 	page_add_new_anon_rmap(page, vma, address);
+	mem_cgroup_commit_charge(page, memcg, false);
+	lru_cache_add_active_or_unevictable(page, vma);
 setpte:
 	set_pte_at(mm, address, page_table, entry);
 
@@ -2679,7 +2683,7 @@ unlock:
 	pte_unmap_unlock(page_table, ptl);
 	return 0;
 release:
-	mem_cgroup_uncharge_page(page);
+	mem_cgroup_cancel_charge(page, memcg);
 	page_cache_release(page);
 	goto unlock;
 oom_free_page:
@@ -2902,6 +2906,7 @@ static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
 {
 	struct page *fault_page, *new_page;
+	struct mem_cgroup *memcg;
 	spinlock_t *ptl;
 	pte_t *pte;
 	int ret;
@@ -2913,7 +2918,7 @@ static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (!new_page)
 		return VM_FAULT_OOM;
 
-	if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) {
+	if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) {
 		page_cache_release(new_page);
 		return VM_FAULT_OOM;
 	}
@@ -2933,12 +2938,14 @@ static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		goto uncharge_out;
 	}
 	do_set_pte(vma, address, new_page, pte, true, true);
+	mem_cgroup_commit_charge(new_page, memcg, false);
+	lru_cache_add_active_or_unevictable(new_page, vma);
 	pte_unmap_unlock(pte, ptl);
 	unlock_page(fault_page);
 	page_cache_release(fault_page);
 	return ret;
 uncharge_out:
-	mem_cgroup_uncharge_page(new_page);
+	mem_cgroup_cancel_charge(new_page, memcg);
 	page_cache_release(new_page);
 	return ret;
 }
diff --git a/mm/rmap.c b/mm/rmap.c
index 3333baab6ece..b4b1d1424ab3 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1026,25 +1026,6 @@ void page_add_new_anon_rmap(struct page *page,
 	__mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
 			hpage_nr_pages(page));
 	__page_set_anon_rmap(page, vma, address, 1);
-
-	VM_BUG_ON_PAGE(PageLRU(page), page);
-	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
-		SetPageActive(page);
-		lru_cache_add(page);
-		return;
-	}
-
-	if (!TestSetPageMlocked(page)) {
-		/*
-		 * We use the irq-unsafe __mod_zone_page_stat because this
-		 * counter is not modified from interrupt context, and the pte
-		 * lock is held(spinlock), which implies preemption disabled.
-		 */
-		__mod_zone_page_state(page_zone(page), NR_MLOCK,
-				    hpage_nr_pages(page));
-		count_vm_event(UNEVICTABLE_PGMLOCKED);
-	}
-	add_page_to_unevictable_list(page);
 }
 
 /**
diff --git a/mm/shmem.c b/mm/shmem.c
index f484c276e994..ea968bf84942 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -668,6 +668,7 @@ int shmem_unuse(swp_entry_t swap, struct page *page)
 {
 	struct list_head *this, *next;
 	struct shmem_inode_info *info;
+	struct mem_cgroup *memcg;
 	int found = 0;
 	int error = 0;
 
@@ -683,7 +684,7 @@ int shmem_unuse(swp_entry_t swap, struct page *page)
 	 * the shmem_swaplist_mutex which might hold up shmem_writepage().
 	 * Charged back to the user (not to caller) when swap account is used.
 	 */
-	error = mem_cgroup_charge_file(page, current->mm, GFP_KERNEL);
+	error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg);
 	if (error)
 		goto out;
 	/* No radix_tree_preload: swap entry keeps a place for page in tree */
@@ -701,8 +702,11 @@ int shmem_unuse(swp_entry_t swap, struct page *page)
 	}
 	mutex_unlock(&shmem_swaplist_mutex);
 
-	if (found < 0)
+	if (found < 0) {
 		error = found;
+		mem_cgroup_cancel_charge(page, memcg);
+	} else
+		mem_cgroup_commit_charge(page, memcg, true);
 out:
 	unlock_page(page);
 	page_cache_release(page);
@@ -1005,6 +1009,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 	struct address_space *mapping = inode->i_mapping;
 	struct shmem_inode_info *info;
 	struct shmem_sb_info *sbinfo;
+	struct mem_cgroup *memcg;
 	struct page *page;
 	swp_entry_t swap;
 	int error;
@@ -1080,8 +1085,7 @@ repeat:
 				goto failed;
 		}
 
-		error = mem_cgroup_charge_file(page, current->mm,
-						gfp & GFP_RECLAIM_MASK);
+		error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
 		if (!error) {
 			error = shmem_add_to_page_cache(page, mapping, index,
 						gfp, swp_to_radix_entry(swap));
@@ -1097,12 +1101,16 @@ repeat:
 			 * Reset swap.val? No, leave it so "failed" goes back to
 			 * "repeat": reading a hole and writing should succeed.
 			 */
-			if (error)
+			if (error) {
+				mem_cgroup_cancel_charge(page, memcg);
 				delete_from_swap_cache(page);
+			}
 		}
 		if (error)
 			goto failed;
 
+		mem_cgroup_commit_charge(page, memcg, true);
+
 		spin_lock(&info->lock);
 		info->swapped--;
 		shmem_recalc_inode(inode);
@@ -1134,8 +1142,7 @@ repeat:
 
 		__SetPageSwapBacked(page);
 		__set_page_locked(page);
-		error = mem_cgroup_charge_file(page, current->mm,
-						gfp & GFP_RECLAIM_MASK);
+		error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
 		if (error)
 			goto decused;
 		error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
@@ -1145,9 +1152,10 @@ repeat:
 			radix_tree_preload_end();
 		}
 		if (error) {
-			mem_cgroup_uncharge_cache_page(page);
+			mem_cgroup_cancel_charge(page, memcg);
 			goto decused;
 		}
+		mem_cgroup_commit_charge(page, memcg, false);
 		lru_cache_add_anon(page);
 
 		spin_lock(&info->lock);
diff --git a/mm/swap.c b/mm/swap.c
index 9e8e3472248b..a98f48626359 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -695,6 +695,40 @@ void add_page_to_unevictable_list(struct page *page)
 	spin_unlock_irq(&zone->lru_lock);
 }
 
+/**
+ * lru_cache_add_active_or_unevictable
+ * @page:  the page to be added to LRU
+ * @vma:   vma in which page is mapped for determining reclaimability
+ *
+ * Place @page on the active or unevictable LRU list, depending on its
+ * evictability.  Note that if the page is not evictable, it goes
+ * directly back onto it's zone's unevictable list, it does NOT use a
+ * per cpu pagevec.
+ */
+void lru_cache_add_active_or_unevictable(struct page *page,
+					 struct vm_area_struct *vma)
+{
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+
+	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED)) {
+		SetPageActive(page);
+		lru_cache_add(page);
+		return;
+	}
+
+	if (!TestSetPageMlocked(page)) {
+		/*
+		 * We use the irq-unsafe __mod_zone_page_stat because this
+		 * counter is not modified from interrupt context, and the pte
+		 * lock is held(spinlock), which implies preemption disabled.
+		 */
+		__mod_zone_page_state(page_zone(page), NR_MLOCK,
+				    hpage_nr_pages(page));
+		count_vm_event(UNEVICTABLE_PGMLOCKED);
+	}
+	add_page_to_unevictable_list(page);
+}
+
 /*
  * If the page can not be invalidated, it is moved to the
  * inactive list to speed up its reclaim.  It is moved to the
diff --git a/mm/swapfile.c b/mm/swapfile.c
index beeeef8a1b2d..3882fcb04ad9 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1129,15 +1129,14 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 	if (unlikely(!page))
 		return -ENOMEM;
 
-	if (mem_cgroup_try_charge_swapin(vma->vm_mm, page,
-					 GFP_KERNEL, &memcg)) {
+	if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg)) {
 		ret = -ENOMEM;
 		goto out_nolock;
 	}
 
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	if (unlikely(!maybe_same_pte(*pte, swp_entry_to_pte(entry)))) {
-		mem_cgroup_cancel_charge_swapin(memcg);
+		mem_cgroup_cancel_charge(page, memcg);
 		ret = 0;
 		goto out;
 	}
@@ -1147,11 +1146,14 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
 	get_page(page);
 	set_pte_at(vma->vm_mm, addr, pte,
 		   pte_mkold(mk_pte(page, vma->vm_page_prot)));
-	if (page == swapcache)
+	if (page == swapcache) {
 		page_add_anon_rmap(page, vma, addr);
-	else /* ksm created a completely new copy */
+		mem_cgroup_commit_charge(page, memcg, true);
+	} else { /* ksm created a completely new copy */
 		page_add_new_anon_rmap(page, vma, addr);
-	mem_cgroup_commit_charge_swapin(page, memcg);
+		mem_cgroup_commit_charge(page, memcg, false);
+		lru_cache_add_active_or_unevictable(page, vma);
+	}
 	swap_free(entry);
 	/*
 	 * Move the page to the active list so it is not
-- 
1.9.3

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[patch 10/10] mm: memcontrol: rewrite uncharge API

[Johannes Weiner]

The memcg uncharging code that is involved towards the end of a page's
lifetime - truncation, reclaim, swapout, migration - is impressively
complicated and fragile.

Because anonymous and file pages were always charged before they had
their page->mapping established, uncharges had to happen when the page
type could still be known from the context; as in unmap for anonymous,
page cache removal for file and shmem pages, and swap cache truncation
for swap pages.  However, these operations happen well before the page
is actually freed, and so a lot of synchronization is necessary:

- Charging, uncharging, page migration, and charge migration all need
  to take a per-page bit spinlock as they could race with uncharging.

- On page migration, the old page might be unmapped but then reused,
  so memcg code has to prevent untimely uncharging in that case.
  Because this code - which should be a simple charge transfer - is so
  special-cased, it is not reusable for replace_page_cache().

- Swap cache truncation happens during both swap-in and swap-out, and
  possibly repeatedly before the page is actually freed.  This means
  that the memcg swapout code is called from many contexts that make
  no sense and it has to figure out the direction from page state to
  make sure memory and memory+swap are always correctly charged.

But now that charged pages always have a page->mapping, introduce
mem_cgroup_uncharge(), which is called after the final put_page(),
when we know for sure that nobody is looking at the page anymore.

Swap accounting is massively simplified: because the page is no longer
uncharged as early as swap cache deletion, a new mem_cgroup_swapout()
can transfer the page's memory+swap charge (PCG_MEMSW) to the swap
entry before the final put_page() in page reclaim.

For page migration, introduce mem_cgroup_migrate(), which is called
after the migration is successful and the new page is fully rmapped.
Because the old page is no longer uncharged after migration, prevent
double charges by decoupling the page's memcg association (PCG_USED
and pc->mem_cgroup) from the page holding an actual charge.  The new
bits PCG_MEM and PCG_MEMSW represent the respective charges and are
transferred to the new page during migration.

mem_cgroup_migrate() is suitable for replace_page_cache() as well,
which gets rid of mem_cgroup_replace_page_cache().

Finally, page_cgroup changes are now protected by whatever protection
the page itself offers: anonymous pages are charged under the page
table lock, whereas page cache insertions, swapin, and migration hold
the page lock.  Uncharging happens under full exclusion with no
outstanding references.  Charging and uncharging also ensure that the
page is off-LRU, which serializes against charge migration.  Remove
the very costly page_cgroup lock and set pc->flags non-atomically.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 Documentation/cgroups/memcg_test.txt | 128 +------
 include/linux/memcontrol.h           |  49 +--
 include/linux/page_cgroup.h          |  43 +--
 include/linux/swap.h                 |  12 +-
 mm/filemap.c                         |   4 +-
 mm/memcontrol.c                      | 676 ++++++++++++-----------------------
 mm/memory.c                          |   2 -
 mm/migrate.c                         |  44 +--
 mm/rmap.c                            |   1 -
 mm/shmem.c                           |   8 +-
 mm/swap.c                            |   6 +
 mm/swap_state.c                      |   8 +-
 mm/swapfile.c                        |   7 +-
 mm/truncate.c                        |   9 -
 mm/vmscan.c                          |  12 +-
 mm/zswap.c                           |   2 +-
 16 files changed, 293 insertions(+), 718 deletions(-)

diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index bcf750d3cecd..8870b0212150 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/Documentation/cgroups/memcg_test.txt
@@ -29,28 +29,13 @@ Please note that implementation details can be changed.
 2. Uncharge
   a page/swp_entry may be uncharged (usage -= PAGE_SIZE) by
 
-	mem_cgroup_uncharge_page()
-	  Called when an anonymous page is fully unmapped. I.e., mapcount goes
-	  to 0. If the page is SwapCache, uncharge is delayed until
-	  mem_cgroup_uncharge_swapcache().
-
-	mem_cgroup_uncharge_cache_page()
-	  Called when a page-cache is deleted from radix-tree. If the page is
-	  SwapCache, uncharge is delayed until mem_cgroup_uncharge_swapcache().
-
-	mem_cgroup_uncharge_swapcache()
-	  Called when SwapCache is removed from radix-tree. The charge itself
-	  is moved to swap_cgroup. (If mem+swap controller is disabled, no
-	  charge to swap occurs.)
+	mem_cgroup_uncharge()
+	  Called when a page's refcount goes down to 0.
 
 	mem_cgroup_uncharge_swap()
 	  Called when swp_entry's refcnt goes down to 0. A charge against swap
 	  disappears.
 
-	mem_cgroup_end_migration(old, new)
-	At success of migration old is uncharged (if necessary), a charge
-	to new page is committed. At failure, charge to old page is committed.
-
 3. charge-commit-cancel
 	Memcg pages are charged in two steps:
 		mem_cgroup_try_charge()
@@ -69,18 +54,6 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 	Anonymous page is newly allocated at
 		  - page fault into MAP_ANONYMOUS mapping.
 		  - Copy-On-Write.
- 	It is charged right after it's allocated before doing any page table
-	related operations. Of course, it's uncharged when another page is used
-	for the fault address.
-
-	At freeing anonymous page (by exit() or munmap()), zap_pte() is called
-	and pages for ptes are freed one by one.(see mm/memory.c). Uncharges
-	are done at page_remove_rmap() when page_mapcount() goes down to 0.
-
-	Another page freeing is by page-reclaim (vmscan.c) and anonymous
-	pages are swapped out. In this case, the page is marked as
-	PageSwapCache(). uncharge() routine doesn't uncharge the page marked
-	as SwapCache(). It's delayed until __delete_from_swap_cache().
 
 	4.1 Swap-in.
 	At swap-in, the page is taken from swap-cache. There are 2 cases.
@@ -89,41 +62,6 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 	(b) If the SwapCache has been mapped by processes, it has been
 	    charged already.
 
-	This swap-in is one of the most complicated work. In do_swap_page(),
-	following events occur when pte is unchanged.
-
-	(1) the page (SwapCache) is looked up.
-	(2) lock_page()
-	(3) try_charge_swapin()
-	(4) reuse_swap_page() (may call delete_swap_cache())
-	(5) commit_charge_swapin()
-	(6) swap_free().
-
-	Considering following situation for example.
-
-	(A) The page has not been charged before (2) and reuse_swap_page()
-	    doesn't call delete_from_swap_cache().
-	(B) The page has not been charged before (2) and reuse_swap_page()
-	    calls delete_from_swap_cache().
-	(C) The page has been charged before (2) and reuse_swap_page() doesn't
-	    call delete_from_swap_cache().
-	(D) The page has been charged before (2) and reuse_swap_page() calls
-	    delete_from_swap_cache().
-
-	    memory.usage/memsw.usage changes to this page/swp_entry will be
-	 Case          (A)      (B)       (C)     (D)
-         Event
-       Before (2)     0/ 1     0/ 1      1/ 1    1/ 1
-          ===========================================
-          (3)        +1/+1    +1/+1     +1/+1   +1/+1
-          (4)          -       0/ 0       -     -1/ 0
-          (5)         0/-1     0/ 0     -1/-1    0/ 0
-          (6)          -       0/-1       -      0/-1
-          ===========================================
-       Result         1/ 1     1/ 1      1/ 1    1/ 1
-
-       In any cases, charges to this page should be 1/ 1.
-
 	4.2 Swap-out.
 	At swap-out, typical state transition is below.
 
@@ -136,28 +74,20 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 	    swp_entry's refcnt -= 1.
 
 
-	At (b), the page is marked as SwapCache and not uncharged.
-	At (d), the page is removed from SwapCache and a charge in page_cgroup
-	is moved to swap_cgroup.
-
 	Finally, at task exit,
 	(e) zap_pte() is called and swp_entry's refcnt -=1 -> 0.
-	Here, a charge in swap_cgroup disappears.
 
 5. Page Cache
    	Page Cache is charged at
 	- add_to_page_cache_locked().
 
-	uncharged at
-	- __remove_from_page_cache().
-
 	The logic is very clear. (About migration, see below)
 	Note: __remove_from_page_cache() is called by remove_from_page_cache()
 	and __remove_mapping().
 
 6. Shmem(tmpfs) Page Cache
-	Memcg's charge/uncharge have special handlers of shmem. The best way
-	to understand shmem's page state transition is to read mm/shmem.c.
+	The best way to understand shmem's page state transition is to read
+	mm/shmem.c.
 	But brief explanation of the behavior of memcg around shmem will be
 	helpful to understand the logic.
 
@@ -170,56 +100,10 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 	It's charged when...
 	- A new page is added to shmem's radix-tree.
 	- A swp page is read. (move a charge from swap_cgroup to page_cgroup)
-	It's uncharged when
-	- A page is removed from radix-tree and not SwapCache.
-	- When SwapCache is removed, a charge is moved to swap_cgroup.
-	- When swp_entry's refcnt goes down to 0, a charge in swap_cgroup
-	  disappears.
 
 7. Page Migration
-   	One of the most complicated functions is page-migration-handler.
-	Memcg has 2 routines. Assume that we are migrating a page's contents
-	from OLDPAGE to NEWPAGE.
-
-	Usual migration logic is..
-	(a) remove the page from LRU.
-	(b) allocate NEWPAGE (migration target)
-	(c) lock by lock_page().
-	(d) unmap all mappings.
-	(e-1) If necessary, replace entry in radix-tree.
-	(e-2) move contents of a page.
-	(f) map all mappings again.
-	(g) pushback the page to LRU.
-	(-) OLDPAGE will be freed.
-
-	Before (g), memcg should complete all necessary charge/uncharge to
-	NEWPAGE/OLDPAGE.
-
-	The point is....
-	- If OLDPAGE is anonymous, all charges will be dropped at (d) because
-          try_to_unmap() drops all mapcount and the page will not be
-	  SwapCache.
-
-	- If OLDPAGE is SwapCache, charges will be kept at (g) because
-	  __delete_from_swap_cache() isn't called at (e-1)
-
-	- If OLDPAGE is page-cache, charges will be kept at (g) because
-	  remove_from_swap_cache() isn't called at (e-1)
-
-	memcg provides following hooks.
-
-	- mem_cgroup_prepare_migration(OLDPAGE)
-	  Called after (b) to account a charge (usage += PAGE_SIZE) against
-	  memcg which OLDPAGE belongs to.
-
-        - mem_cgroup_end_migration(OLDPAGE, NEWPAGE)
-	  Called after (f) before (g).
-	  If OLDPAGE is used, commit OLDPAGE again. If OLDPAGE is already
-	  charged, a charge by prepare_migration() is automatically canceled.
-	  If NEWPAGE is used, commit NEWPAGE and uncharge OLDPAGE.
-
-	  But zap_pte() (by exit or munmap) can be called while migration,
-	  we have to check if OLDPAGE/NEWPAGE is a valid page after commit().
+
+	mem_cgroup_migrate()
 
 8. LRU
         Each memcg has its own private LRU. Now, its handling is under global
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index bd2cc35babe0..f0c537786739 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -60,15 +60,17 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
 			      bool lrucare);
 void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg);
 
-struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
-struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
+void mem_cgroup_uncharge(struct page *page);
+
+/* Batched uncharging */
+void mem_cgroup_uncharge_start(void);
+void mem_cgroup_uncharge_end(void);
 
-/* For coalescing uncharge for reducing memcg' overhead*/
-extern void mem_cgroup_uncharge_start(void);
-extern void mem_cgroup_uncharge_end(void);
+void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
+			bool lrucare);
 
-extern void mem_cgroup_uncharge_page(struct page *page);
-extern void mem_cgroup_uncharge_cache_page(struct page *page);
+struct lruvec *mem_cgroup_zone_lruvec(struct zone *, struct mem_cgroup *);
+struct lruvec *mem_cgroup_page_lruvec(struct page *, struct zone *);
 
 bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
 				  struct mem_cgroup *memcg);
@@ -100,12 +102,6 @@ bool mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *memcg)
 
 extern struct cgroup_subsys_state *mem_cgroup_css(struct mem_cgroup *memcg);
 
-extern void
-mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
-			     struct mem_cgroup **memcgp);
-extern void mem_cgroup_end_migration(struct mem_cgroup *memcg,
-	struct page *oldpage, struct page *newpage, bool migration_ok);
-
 struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *,
 				   struct mem_cgroup *,
 				   struct mem_cgroup_reclaim_cookie *);
@@ -120,8 +116,6 @@ unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list);
 void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int);
 extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
 					struct task_struct *p);
-extern void mem_cgroup_replace_page_cache(struct page *oldpage,
-					struct page *newpage);
 
 static inline void mem_cgroup_oom_enable(void)
 {
@@ -239,19 +233,21 @@ static inline void mem_cgroup_cancel_charge(struct page *page,
 {
 }
 
-static inline void mem_cgroup_uncharge_start(void)
+static inline void mem_cgroup_uncharge(struct page *page)
 {
 }
 
-static inline void mem_cgroup_uncharge_end(void)
+static inline void mem_cgroup_uncharge_start(void)
 {
 }
 
-static inline void mem_cgroup_uncharge_page(struct page *page)
+static inline void mem_cgroup_uncharge_end(void)
 {
 }
 
-static inline void mem_cgroup_uncharge_cache_page(struct page *page)
+static inline void mem_cgroup_migrate(struct page *oldpage,
+				      struct page *newpage,
+				      bool lrucare)
 {
 }
 
@@ -300,17 +296,6 @@ static inline struct cgroup_subsys_state
 	return NULL;
 }
 
-static inline void
-mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
-			     struct mem_cgroup **memcgp)
-{
-}
-
-static inline void mem_cgroup_end_migration(struct mem_cgroup *memcg,
-		struct page *oldpage, struct page *newpage, bool migration_ok)
-{
-}
-
 static inline struct mem_cgroup *
 mem_cgroup_iter(struct mem_cgroup *root,
 		struct mem_cgroup *prev,
@@ -406,10 +391,6 @@ static inline
 void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx)
 {
 }
-static inline void mem_cgroup_replace_page_cache(struct page *oldpage,
-				struct page *newpage)
-{
-}
 #endif /* CONFIG_MEMCG */
 
 #if !defined(CONFIG_MEMCG) || !defined(CONFIG_DEBUG_VM)
diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 777a524716db..97b5c39a31c8 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -3,9 +3,9 @@
 
 enum {
 	/* flags for mem_cgroup */
-	PCG_LOCK,  /* Lock for pc->mem_cgroup and following bits. */
-	PCG_USED, /* this object is in use. */
-	PCG_MIGRATION, /* under page migration */
+	PCG_USED,	/* This page is charged to a memcg */
+	PCG_MEM,	/* This page holds a memory charge */
+	PCG_MEMSW,	/* This page holds a memory+swap charge */
 	__NR_PCG_FLAGS,
 };
 
@@ -44,42 +44,9 @@ static inline void __init page_cgroup_init(void)
 struct page_cgroup *lookup_page_cgroup(struct page *page);
 struct page *lookup_cgroup_page(struct page_cgroup *pc);
 
-#define TESTPCGFLAG(uname, lname)			\
-static inline int PageCgroup##uname(struct page_cgroup *pc)	\
-	{ return test_bit(PCG_##lname, &pc->flags); }
-
-#define SETPCGFLAG(uname, lname)			\
-static inline void SetPageCgroup##uname(struct page_cgroup *pc)\
-	{ set_bit(PCG_##lname, &pc->flags);  }
-
-#define CLEARPCGFLAG(uname, lname)			\
-static inline void ClearPageCgroup##uname(struct page_cgroup *pc)	\
-	{ clear_bit(PCG_##lname, &pc->flags);  }
-
-#define TESTCLEARPCGFLAG(uname, lname)			\
-static inline int TestClearPageCgroup##uname(struct page_cgroup *pc)	\
-	{ return test_and_clear_bit(PCG_##lname, &pc->flags);  }
-
-TESTPCGFLAG(Used, USED)
-CLEARPCGFLAG(Used, USED)
-SETPCGFLAG(Used, USED)
-
-SETPCGFLAG(Migration, MIGRATION)
-CLEARPCGFLAG(Migration, MIGRATION)
-TESTPCGFLAG(Migration, MIGRATION)
-
-static inline void lock_page_cgroup(struct page_cgroup *pc)
-{
-	/*
-	 * Don't take this lock in IRQ context.
-	 * This lock is for pc->mem_cgroup, USED, MIGRATION
-	 */
-	bit_spin_lock(PCG_LOCK, &pc->flags);
-}
-
-static inline void unlock_page_cgroup(struct page_cgroup *pc)
+static inline int PageCgroupUsed(struct page_cgroup *pc)
 {
-	bit_spin_unlock(PCG_LOCK, &pc->flags);
+	return test_bit(PCG_USED, &pc->flags);
 }
 
 #else /* CONFIG_MEMCG */
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 290905133078..94fd0b23f3f9 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -382,9 +382,13 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 }
 #endif
 #ifdef CONFIG_MEMCG_SWAP
-extern void mem_cgroup_uncharge_swap(swp_entry_t ent);
+extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
+extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
 #else
-static inline void mem_cgroup_uncharge_swap(swp_entry_t ent)
+static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+{
+}
+static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
 {
 }
 #endif
@@ -444,7 +448,7 @@ extern void swap_shmem_alloc(swp_entry_t);
 extern int swap_duplicate(swp_entry_t);
 extern int swapcache_prepare(swp_entry_t);
 extern void swap_free(swp_entry_t);
-extern void swapcache_free(swp_entry_t, struct page *page);
+extern void swapcache_free(swp_entry_t);
 extern int free_swap_and_cache(swp_entry_t);
 extern int swap_type_of(dev_t, sector_t, struct block_device **);
 extern unsigned int count_swap_pages(int, int);
@@ -508,7 +512,7 @@ static inline void swap_free(swp_entry_t swp)
 {
 }
 
-static inline void swapcache_free(swp_entry_t swp, struct page *page)
+static inline void swapcache_free(swp_entry_t swp)
 {
 }
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 114cd89c1cc2..c2f30ed8e95f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -233,7 +233,6 @@ void delete_from_page_cache(struct page *page)
 	spin_lock_irq(&mapping->tree_lock);
 	__delete_from_page_cache(page, NULL);
 	spin_unlock_irq(&mapping->tree_lock);
-	mem_cgroup_uncharge_cache_page(page);
 
 	if (freepage)
 		freepage(page);
@@ -501,8 +500,7 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 		if (PageSwapBacked(new))
 			__inc_zone_page_state(new, NR_SHMEM);
 		spin_unlock_irq(&mapping->tree_lock);
-		/* mem_cgroup codes must not be called under tree_lock */
-		mem_cgroup_replace_page_cache(old, new);
+		mem_cgroup_migrate(old, new, true);
 		radix_tree_preload_end();
 		if (freepage)
 			freepage(old);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9458c9e3e08c..ce490c8a98dd 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -909,13 +909,13 @@ static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
 
 static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
 					 struct page *page,
-					 bool anon, int nr_pages)
+					 int nr_pages)
 {
 	/*
 	 * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
 	 * counted as CACHE even if it's on ANON LRU.
 	 */
-	if (anon)
+	if (PageAnon(page))
 		__this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
 				nr_pages);
 	else
@@ -1347,20 +1347,6 @@ out:
 	return lruvec;
 }
 
-/*
- * Following LRU functions are allowed to be used without PCG_LOCK.
- * Operations are called by routine of global LRU independently from memcg.
- * What we have to take care of here is validness of pc->mem_cgroup.
- *
- * Changes to pc->mem_cgroup happens when
- * 1. charge
- * 2. moving account
- * In typical case, "charge" is done before add-to-lru. Exception is SwapCache.
- * It is added to LRU before charge.
- * If PCG_USED bit is not set, page_cgroup is not added to this private LRU.
- * When moving account, the page is not on LRU. It's isolated.
- */
-
 /**
  * mem_cgroup_page_lruvec - return lruvec for adding an lru page
  * @page: the page
@@ -2262,22 +2248,14 @@ cleanup:
  *
  * Notes: Race condition
  *
- * We usually use lock_page_cgroup() for accessing page_cgroup member but
- * it tends to be costly. But considering some conditions, we doesn't need
- * to do so _always_.
- *
- * Considering "charge", lock_page_cgroup() is not required because all
- * file-stat operations happen after a page is attached to radix-tree. There
- * are no race with "charge".
+ * Charging occurs during page instantiation, while the page is
+ * unmapped and locked in page migration, or while the page table is
+ * locked in THP migration.  No race is possible.
  *
- * Considering "uncharge", we know that memcg doesn't clear pc->mem_cgroup
- * at "uncharge" intentionally. So, we always see valid pc->mem_cgroup even
- * if there are race with "uncharge". Statistics itself is properly handled
- * by flags.
+ * Uncharge happens to pages with zero references, no race possible.
  *
- * Considering "move", this is an only case we see a race. To make the race
- * small, we check memcg->moving_account and detect there are possibility
- * of race or not. If there is, we take a lock.
+ * Charge moving between groups is protected by checking mm->moving
+ * account and taking the move_lock in the slowpath.
  */
 
 void __mem_cgroup_begin_update_page_stat(struct page *page,
@@ -2733,6 +2711,16 @@ bool mem_cgroup_all_within_guarantee(struct mem_cgroup *root)
 	return true;
 }
 
+/*
+ * try_get_mem_cgroup_from_page - look up page's memcg association
+ * @page: the page
+ *
+ * Look up, get a css reference, and return the memcg that owns @page.
+ *
+ * The page must be locked to prevent racing with swap-in and page
+ * cache charges.  If coming from an unlocked page table, the caller
+ * must ensure the page is on the LRU or this can race with charging.
+ */
 struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
 {
 	struct mem_cgroup *memcg = NULL;
@@ -2743,7 +2731,6 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 
 	pc = lookup_page_cgroup(page);
-	lock_page_cgroup(pc);
 	if (PageCgroupUsed(pc)) {
 		memcg = pc->mem_cgroup;
 		if (memcg && !css_tryget_online(&memcg->css))
@@ -2757,19 +2744,17 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
 			memcg = NULL;
 		rcu_read_unlock();
 	}
-	unlock_page_cgroup(pc);
 	return memcg;
 }
 
 static void commit_charge(struct page *page, struct mem_cgroup *memcg,
-			  unsigned int nr_pages, bool anon, bool lrucare)
+			  unsigned int nr_pages, bool lrucare)
 {
 	struct page_cgroup *pc = lookup_page_cgroup(page);
 	struct zone *uninitialized_var(zone);
 	struct lruvec *lruvec;
 	bool was_on_lru = false;
 
-	lock_page_cgroup(pc);
 	VM_BUG_ON_PAGE(PageCgroupUsed(pc), page);
 	/*
 	 * we don't need page_cgroup_lock about tail pages, becase they are not
@@ -2791,8 +2776,22 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 		}
 	}
 
+	/*
+	 * Nobody should be changing or seriously looking at
+	 * pc->mem_cgroup and pc->flags at this point:
+	 *
+	 * - the page is uncharged
+	 *
+	 * - the page is off-LRU
+	 *
+	 * - an anonymous fault has exclusive page access, except for
+	 *   a locked page table
+	 *
+	 * - a page cache insertion, a swapin fault, or a migration
+	 *   have the page locked
+	 */
 	pc->mem_cgroup = memcg;
-	SetPageCgroupUsed(pc);
+	pc->flags = PCG_USED | PCG_MEM | PCG_MEMSW;
 
 	if (lrucare) {
 		if (was_on_lru) {
@@ -2804,9 +2803,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 		spin_unlock_irq(&zone->lru_lock);
 	}
 
-	mem_cgroup_charge_statistics(memcg, page, anon, nr_pages);
-	unlock_page_cgroup(pc);
-
+	mem_cgroup_charge_statistics(memcg, page, nr_pages);
 	/*
 	 * "charge_statistics" updated event counter. Then, check it.
 	 * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
@@ -3439,7 +3436,6 @@ static inline void memcg_unregister_all_caches(struct mem_cgroup *memcg)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 
-#define PCGF_NOCOPY_AT_SPLIT (1 << PCG_LOCK | 1 << PCG_MIGRATION)
 /*
  * Because tail pages are not marked as "used", set it. We're under
  * zone->lru_lock, 'splitting on pmd' and compound_lock.
@@ -3460,7 +3456,7 @@ void mem_cgroup_split_huge_fixup(struct page *head)
 	for (i = 1; i < HPAGE_PMD_NR; i++) {
 		pc = head_pc + i;
 		pc->mem_cgroup = memcg;
-		pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;
+		pc->flags = head_pc->flags;
 	}
 	__this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE],
 		       HPAGE_PMD_NR);
@@ -3490,7 +3486,6 @@ static int mem_cgroup_move_account(struct page *page,
 {
 	unsigned long flags;
 	int ret;
-	bool anon = PageAnon(page);
 
 	VM_BUG_ON(from == to);
 	VM_BUG_ON_PAGE(PageLRU(page), page);
@@ -3504,15 +3499,13 @@ static int mem_cgroup_move_account(struct page *page,
 	if (nr_pages > 1 && !PageTransHuge(page))
 		goto out;
 
-	lock_page_cgroup(pc);
-
 	ret = -EINVAL;
 	if (!PageCgroupUsed(pc) || pc->mem_cgroup != from)
-		goto unlock;
+		goto out;
 
 	move_lock_mem_cgroup(from, &flags);
 
-	if (!anon && page_mapped(page)) {
+	if (!PageAnon(page) && page_mapped(page)) {
 		__this_cpu_sub(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
 			       nr_pages);
 		__this_cpu_add(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED],
@@ -3526,15 +3519,19 @@ static int mem_cgroup_move_account(struct page *page,
 			       nr_pages);
 	}
 
-	mem_cgroup_charge_statistics(from, page, anon, -nr_pages);
+	mem_cgroup_charge_statistics(from, page, -nr_pages);
+
+	/*
+	 * It is safe to change pc->mem_cgroup here because the page
+	 * is referenced, charged, and isolated - we can't race with
+	 * uncharging, charging, migration, or LRU putback.
+	 */
 
 	/* caller should have done css_get */
 	pc->mem_cgroup = to;
-	mem_cgroup_charge_statistics(to, page, anon, nr_pages);
+	mem_cgroup_charge_statistics(to, page, nr_pages);
 	move_unlock_mem_cgroup(from, &flags);
 	ret = 0;
-unlock:
-	unlock_page_cgroup(pc);
 	/*
 	 * check events
 	 */
@@ -3610,193 +3607,6 @@ out:
 	return ret;
 }
 
-static void mem_cgroup_do_uncharge(struct mem_cgroup *memcg,
-				   unsigned int nr_pages,
-				   const enum charge_type ctype)
-{
-	struct memcg_batch_info *batch = NULL;
-	bool uncharge_memsw = true;
-
-	/* If swapout, usage of swap doesn't decrease */
-	if (!do_swap_account || ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
-		uncharge_memsw = false;
-
-	batch = &current->memcg_batch;
-	/*
-	 * In usual, we do css_get() when we remember memcg pointer.
-	 * But in this case, we keep res->usage until end of a series of
-	 * uncharges. Then, it's ok to ignore memcg's refcnt.
-	 */
-	if (!batch->memcg)
-		batch->memcg = memcg;
-	/*
-	 * do_batch > 0 when unmapping pages or inode invalidate/truncate.
-	 * In those cases, all pages freed continuously can be expected to be in
-	 * the same cgroup and we have chance to coalesce uncharges.
-	 * But we do uncharge one by one if this is killed by OOM(TIF_MEMDIE)
-	 * because we want to do uncharge as soon as possible.
-	 */
-
-	if (!batch->do_batch || test_thread_flag(TIF_MEMDIE))
-		goto direct_uncharge;
-
-	if (nr_pages > 1)
-		goto direct_uncharge;
-
-	/*
-	 * In typical case, batch->memcg == mem. This means we can
-	 * merge a series of uncharges to an uncharge of res_counter.
-	 * If not, we uncharge res_counter ony by one.
-	 */
-	if (batch->memcg != memcg)
-		goto direct_uncharge;
-	/* remember freed charge and uncharge it later */
-	batch->nr_pages++;
-	if (uncharge_memsw)
-		batch->memsw_nr_pages++;
-	return;
-direct_uncharge:
-	res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
-	if (uncharge_memsw)
-		res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
-	if (unlikely(batch->memcg != memcg))
-		memcg_oom_recover(memcg);
-}
-
-/*
- * uncharge if !page_mapped(page)
- */
-static struct mem_cgroup *
-__mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
-			     bool end_migration)
-{
-	struct mem_cgroup *memcg = NULL;
-	unsigned int nr_pages = 1;
-	struct page_cgroup *pc;
-	bool anon;
-
-	if (mem_cgroup_disabled())
-		return NULL;
-
-	if (PageTransHuge(page)) {
-		nr_pages <<= compound_order(page);
-		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
-	}
-	/*
-	 * Check if our page_cgroup is valid
-	 */
-	pc = lookup_page_cgroup(page);
-	if (unlikely(!PageCgroupUsed(pc)))
-		return NULL;
-
-	lock_page_cgroup(pc);
-
-	memcg = pc->mem_cgroup;
-
-	if (!PageCgroupUsed(pc))
-		goto unlock_out;
-
-	anon = PageAnon(page);
-
-	switch (ctype) {
-	case MEM_CGROUP_CHARGE_TYPE_ANON:
-		/*
-		 * Generally PageAnon tells if it's the anon statistics to be
-		 * updated; but sometimes e.g. mem_cgroup_uncharge_page() is
-		 * used before page reached the stage of being marked PageAnon.
-		 */
-		anon = true;
-		/* fallthrough */
-	case MEM_CGROUP_CHARGE_TYPE_DROP:
-		/* See mem_cgroup_prepare_migration() */
-		if (page_mapped(page))
-			goto unlock_out;
-		/*
-		 * Pages under migration may not be uncharged.  But
-		 * end_migration() /must/ be the one uncharging the
-		 * unused post-migration page and so it has to call
-		 * here with the migration bit still set.  See the
-		 * res_counter handling below.
-		 */
-		if (!end_migration && PageCgroupMigration(pc))
-			goto unlock_out;
-		break;
-	case MEM_CGROUP_CHARGE_TYPE_SWAPOUT:
-		if (!PageAnon(page)) {	/* Shared memory */
-			if (page->mapping && !page_is_file_cache(page))
-				goto unlock_out;
-		} else if (page_mapped(page)) /* Anon */
-				goto unlock_out;
-		break;
-	default:
-		break;
-	}
-
-	mem_cgroup_charge_statistics(memcg, page, anon, -nr_pages);
-
-	ClearPageCgroupUsed(pc);
-	/*
-	 * pc->mem_cgroup is not cleared here. It will be accessed when it's
-	 * freed from LRU. This is safe because uncharged page is expected not
-	 * to be reused (freed soon). Exception is SwapCache, it's handled by
-	 * special functions.
-	 */
-
-	unlock_page_cgroup(pc);
-	/*
-	 * even after unlock, we have memcg->res.usage here and this memcg
-	 * will never be freed, so it's safe to call css_get().
-	 */
-	memcg_check_events(memcg, page);
-	if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
-		mem_cgroup_swap_statistics(memcg, true);
-		css_get(&memcg->css);
-	}
-	/*
-	 * Migration does not charge the res_counter for the
-	 * replacement page, so leave it alone when phasing out the
-	 * page that is unused after the migration.
-	 */
-	if (!end_migration)
-		mem_cgroup_do_uncharge(memcg, nr_pages, ctype);
-
-	return memcg;
-
-unlock_out:
-	unlock_page_cgroup(pc);
-	return NULL;
-}
-
-void mem_cgroup_uncharge_page(struct page *page)
-{
-	/* early check. */
-	if (page_mapped(page))
-		return;
-	VM_BUG_ON_PAGE(page->mapping && !PageAnon(page), page);
-	/*
-	 * If the page is in swap cache, uncharge should be deferred
-	 * to the swap path, which also properly accounts swap usage
-	 * and handles memcg lifetime.
-	 *
-	 * Note that this check is not stable and reclaim may add the
-	 * page to swap cache at any time after this.  However, if the
-	 * page is not in swap cache by the time page->mapcount hits
-	 * 0, there won't be any page table references to the swap
-	 * slot, and reclaim will free it and not actually write the
-	 * page to disk.
-	 */
-	if (PageSwapCache(page))
-		return;
-	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_ANON, false);
-}
-
-void mem_cgroup_uncharge_cache_page(struct page *page)
-{
-	VM_BUG_ON_PAGE(page_mapped(page), page);
-	VM_BUG_ON_PAGE(page->mapping, page);
-	__mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE, false);
-}
-
 /*
  * Batch_start/batch_end is called in unmap_page_range/invlidate/trucate.
  * In that cases, pages are freed continuously and we can expect pages
@@ -3844,59 +3654,7 @@ void mem_cgroup_uncharge_end(void)
 	batch->memcg = NULL;
 }
 
-#ifdef CONFIG_SWAP
-/*
- * called after __delete_from_swap_cache() and drop "page" account.
- * memcg information is recorded to swap_cgroup of "ent"
- */
-void
-mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
-{
-	struct mem_cgroup *memcg;
-	int ctype = MEM_CGROUP_CHARGE_TYPE_SWAPOUT;
-
-	if (!swapout) /* this was a swap cache but the swap is unused ! */
-		ctype = MEM_CGROUP_CHARGE_TYPE_DROP;
-
-	memcg = __mem_cgroup_uncharge_common(page, ctype, false);
-
-	/*
-	 * record memcg information,  if swapout && memcg != NULL,
-	 * css_get() was called in uncharge().
-	 */
-	if (do_swap_account && swapout && memcg)
-		swap_cgroup_record(ent, mem_cgroup_id(memcg));
-}
-#endif
-
 #ifdef CONFIG_MEMCG_SWAP
-/*
- * called from swap_entry_free(). remove record in swap_cgroup and
- * uncharge "memsw" account.
- */
-void mem_cgroup_uncharge_swap(swp_entry_t ent)
-{
-	struct mem_cgroup *memcg;
-	unsigned short id;
-
-	if (!do_swap_account)
-		return;
-
-	id = swap_cgroup_record(ent, 0);
-	rcu_read_lock();
-	memcg = mem_cgroup_lookup(id);
-	if (memcg) {
-		/*
-		 * We uncharge this because swap is freed.  This memcg can
-		 * be obsolete one. We avoid calling css_tryget_online().
-		 */
-		res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
-		mem_cgroup_swap_statistics(memcg, false);
-		css_put(&memcg->css);
-	}
-	rcu_read_unlock();
-}
-
 /**
  * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
  * @entry: swap entry to be moved
@@ -3946,169 +3704,6 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
 }
 #endif
 
-/*
- * Before starting migration, account PAGE_SIZE to mem_cgroup that the old
- * page belongs to.
- */
-void mem_cgroup_prepare_migration(struct page *page, struct page *newpage,
-				  struct mem_cgroup **memcgp)
-{
-	struct mem_cgroup *memcg = NULL;
-	unsigned int nr_pages = 1;
-	struct page_cgroup *pc;
-
-	*memcgp = NULL;
-
-	if (mem_cgroup_disabled())
-		return;
-
-	if (PageTransHuge(page))
-		nr_pages <<= compound_order(page);
-
-	pc = lookup_page_cgroup(page);
-	lock_page_cgroup(pc);
-	if (PageCgroupUsed(pc)) {
-		memcg = pc->mem_cgroup;
-		css_get(&memcg->css);
-		/*
-		 * At migrating an anonymous page, its mapcount goes down
-		 * to 0 and uncharge() will be called. But, even if it's fully
-		 * unmapped, migration may fail and this page has to be
-		 * charged again. We set MIGRATION flag here and delay uncharge
-		 * until end_migration() is called
-		 *
-		 * Corner Case Thinking
-		 * A)
-		 * When the old page was mapped as Anon and it's unmap-and-freed
-		 * while migration was ongoing.
-		 * If unmap finds the old page, uncharge() of it will be delayed
-		 * until end_migration(). If unmap finds a new page, it's
-		 * uncharged when it make mapcount to be 1->0. If unmap code
-		 * finds swap_migration_entry, the new page will not be mapped
-		 * and end_migration() will find it(mapcount==0).
-		 *
-		 * B)
-		 * When the old page was mapped but migraion fails, the kernel
-		 * remaps it. A charge for it is kept by MIGRATION flag even
-		 * if mapcount goes down to 0. We can do remap successfully
-		 * without charging it again.
-		 *
-		 * C)
-		 * The "old" page is under lock_page() until the end of
-		 * migration, so, the old page itself will not be swapped-out.
-		 * If the new page is swapped out before end_migraton, our
-		 * hook to usual swap-out path will catch the event.
-		 */
-		if (PageAnon(page))
-			SetPageCgroupMigration(pc);
-	}
-	unlock_page_cgroup(pc);
-	/*
-	 * If the page is not charged at this point,
-	 * we return here.
-	 */
-	if (!memcg)
-		return;
-
-	*memcgp = memcg;
-	/*
-	 * We charge new page before it's used/mapped. So, even if unlock_page()
-	 * is called before end_migration, we can catch all events on this new
-	 * page. In the case new page is migrated but not remapped, new page's
-	 * mapcount will be finally 0 and we call uncharge in end_migration().
-	 */
-	/*
-	 * The page is committed to the memcg, but it's not actually
-	 * charged to the res_counter since we plan on replacing the
-	 * old one and only one page is going to be left afterwards.
-	 */
-	commit_charge(newpage, memcg, nr_pages, PageAnon(page), false);
-}
-
-/* remove redundant charge if migration failed*/
-void mem_cgroup_end_migration(struct mem_cgroup *memcg,
-	struct page *oldpage, struct page *newpage, bool migration_ok)
-{
-	struct page *used, *unused;
-	struct page_cgroup *pc;
-	bool anon;
-
-	if (!memcg)
-		return;
-
-	if (!migration_ok) {
-		used = oldpage;
-		unused = newpage;
-	} else {
-		used = newpage;
-		unused = oldpage;
-	}
-	anon = PageAnon(used);
-	__mem_cgroup_uncharge_common(unused,
-				     anon ? MEM_CGROUP_CHARGE_TYPE_ANON
-				     : MEM_CGROUP_CHARGE_TYPE_CACHE,
-				     true);
-	css_put(&memcg->css);
-	/*
-	 * We disallowed uncharge of pages under migration because mapcount
-	 * of the page goes down to zero, temporarly.
-	 * Clear the flag and check the page should be charged.
-	 */
-	pc = lookup_page_cgroup(oldpage);
-	lock_page_cgroup(pc);
-	ClearPageCgroupMigration(pc);
-	unlock_page_cgroup(pc);
-
-	/*
-	 * If a page is a file cache, radix-tree replacement is very atomic
-	 * and we can skip this check. When it was an Anon page, its mapcount
-	 * goes down to 0. But because we added MIGRATION flage, it's not
-	 * uncharged yet. There are several case but page->mapcount check
-	 * and USED bit check in mem_cgroup_uncharge_page() will do enough
-	 * check. (see prepare_charge() also)
-	 */
-	if (anon)
-		mem_cgroup_uncharge_page(used);
-}
-
-/*
- * At replace page cache, newpage is not under any memcg but it's on
- * LRU. So, this function doesn't touch res_counter but handles LRU
- * in correct way. Both pages are locked so we cannot race with uncharge.
- */
-void mem_cgroup_replace_page_cache(struct page *oldpage,
-				  struct page *newpage)
-{
-	struct mem_cgroup *memcg = NULL;
-	struct page_cgroup *pc;
-
-	if (mem_cgroup_disabled())
-		return;
-
-	pc = lookup_page_cgroup(oldpage);
-	/* fix accounting on old pages */
-	lock_page_cgroup(pc);
-	if (PageCgroupUsed(pc)) {
-		memcg = pc->mem_cgroup;
-		mem_cgroup_charge_statistics(memcg, oldpage, false, -1);
-		ClearPageCgroupUsed(pc);
-	}
-	unlock_page_cgroup(pc);
-
-	/*
-	 * When called from shmem_replace_page(), in some cases the
-	 * oldpage has already been charged, and in some cases not.
-	 */
-	if (!memcg)
-		return;
-	/*
-	 * Even if newpage->mapping was NULL before starting replacement,
-	 * the newpage may be on LRU(or pagevec for LRU) already. We lock
-	 * LRU while we overwrite pc->mem_cgroup.
-	 */
-	commit_charge(newpage, memcg, 1, false, true);
-}
-
 #ifdef CONFIG_DEBUG_VM
 static struct page_cgroup *lookup_page_cgroup_used(struct page *page)
 {
@@ -6331,9 +5926,9 @@ static enum mc_target_type get_mctgt_type(struct vm_area_struct *vma,
 	if (page) {
 		pc = lookup_page_cgroup(page);
 		/*
-		 * Do only loose check w/o page_cgroup lock.
-		 * mem_cgroup_move_account() checks the pc is valid or not under
-		 * the lock.
+		 * Do only loose check w/o serialization.
+		 * mem_cgroup_move_account() checks the pc is valid or
+		 * not under LRU exclusion.
 		 */
 		if (PageCgroupUsed(pc) && pc->mem_cgroup == mc.from) {
 			ret = MC_TARGET_PAGE;
@@ -6775,6 +6370,67 @@ static void __init enable_swap_cgroup(void)
 }
 #endif
 
+#ifdef CONFIG_MEMCG_SWAP
+/**
+ * mem_cgroup_swapout - transfer a memsw charge to swap
+ * @page: page whose memsw charge to transfer
+ * @entry: swap entry to move the charge to
+ *
+ * Transfer the memsw charge of @page to @entry.
+ */
+void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
+{
+	struct page_cgroup *pc;
+	unsigned short oldid;
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(page_count(page), page);
+
+	if (!do_swap_account)
+		return;
+
+	pc = lookup_page_cgroup(page);
+
+	/* Readahead page, never charged */
+	if (!PageCgroupUsed(pc))
+		return;
+
+	VM_BUG_ON_PAGE(!(pc->flags & PCG_MEMSW), page);
+
+	oldid = swap_cgroup_record(entry, mem_cgroup_id(pc->mem_cgroup));
+	VM_BUG_ON_PAGE(oldid, page);
+
+	pc->flags &= ~PCG_MEMSW;
+	css_get(&pc->mem_cgroup->css);
+	mem_cgroup_swap_statistics(pc->mem_cgroup, true);
+}
+
+/**
+ * mem_cgroup_uncharge_swap - uncharge a swap entry
+ * @entry: swap entry to uncharge
+ *
+ * Drop the memsw charge associated with @entry.
+ */
+void mem_cgroup_uncharge_swap(swp_entry_t entry)
+{
+	struct mem_cgroup *memcg;
+	unsigned short id;
+
+	if (!do_swap_account)
+		return;
+
+	id = swap_cgroup_record(entry, 0);
+	rcu_read_lock();
+	memcg = mem_cgroup_lookup(id);
+	if (memcg) {
+		res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
+		mem_cgroup_swap_statistics(memcg, false);
+		css_put(&memcg->css);
+	}
+	rcu_read_unlock();
+}
+#endif
+
 /**
  * mem_cgroup_try_charge - try charging a page
  * @page: page to charge
@@ -6883,7 +6539,7 @@ void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg,
 		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
 	}
 
-	commit_charge(page, memcg, nr_pages, PageAnon(page), lrucare);
+	commit_charge(page, memcg, nr_pages, lrucare);
 
 	if (do_swap_account && PageSwapCache(page)) {
 		swp_entry_t entry = { .val = page_private(page) };
@@ -6925,6 +6581,116 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
 	cancel_charge(memcg, nr_pages);
 }
 
+/**
+ * mem_cgroup_uncharge - uncharge a page
+ * @page: page to uncharge
+ *
+ * Uncharge a page previously charged with mem_cgroup_try_charge() and
+ * mem_cgroup_commit_charge().
+ */
+void mem_cgroup_uncharge(struct page *page)
+{
+	struct memcg_batch_info *batch;
+	unsigned int nr_pages = 1;
+	struct mem_cgroup *memcg;
+	struct page_cgroup *pc;
+	unsigned long flags;
+
+	VM_BUG_ON_PAGE(PageLRU(page), page);
+	VM_BUG_ON_PAGE(page_count(page), page);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	pc = lookup_page_cgroup(page);
+
+	/* Every final put_page() ends up here */
+	if (!PageCgroupUsed(pc))
+		return;
+
+	if (PageTransHuge(page)) {
+		nr_pages <<= compound_order(page);
+		VM_BUG_ON_PAGE(!PageTransHuge(page), page);
+	}
+	/*
+	 * Nobody should be changing or seriously looking at
+	 * pc->mem_cgroup and pc->flags at this point, we have fully
+	 * exclusive access to the page.
+	 */
+	memcg = pc->mem_cgroup;
+	flags = pc->flags;
+	pc->flags = 0;
+
+	mem_cgroup_charge_statistics(memcg, page, -nr_pages);
+	memcg_check_events(memcg, page);
+
+	batch = &current->memcg_batch;
+	if (!batch->memcg)
+		batch->memcg = memcg;
+	else if (batch->memcg != memcg)
+		goto uncharge;
+	if (nr_pages > 1)
+		goto uncharge;
+	if (!batch->do_batch)
+		goto uncharge;
+	if (test_thread_flag(TIF_MEMDIE))
+		goto uncharge;
+	if (flags & PCG_MEM)
+		batch->nr_pages++;
+	if (flags & PCG_MEMSW)
+		batch->memsw_nr_pages++;
+	return;
+uncharge:
+	if (flags & PCG_MEM)
+		res_counter_uncharge(&memcg->res, nr_pages * PAGE_SIZE);
+	if (flags & PCG_MEMSW)
+		res_counter_uncharge(&memcg->memsw, nr_pages * PAGE_SIZE);
+	if (batch->memcg != memcg)
+		memcg_oom_recover(memcg);
+}
+
+/**
+ * mem_cgroup_migrate - migrate a charge to another page
+ * @oldpage: currently charged page
+ * @newpage: page to transfer the charge to
+ * @lrucare: page might be on LRU already
+ *
+ * Migrate the charge from @oldpage to @newpage.
+ *
+ * Both pages must be locked, @newpage->mapping must be set up.
+ */
+void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
+			bool lrucare)
+{
+	unsigned int nr_pages = 1;
+	struct page_cgroup *pc;
+
+	VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
+	VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
+	VM_BUG_ON_PAGE(PageLRU(oldpage), oldpage);
+	VM_BUG_ON_PAGE(PageLRU(newpage), newpage);
+	VM_BUG_ON_PAGE(PageAnon(oldpage) != PageAnon(newpage), newpage);
+
+	if (mem_cgroup_disabled())
+		return;
+
+	pc = lookup_page_cgroup(oldpage);
+	if (!PageCgroupUsed(pc))
+		return;
+
+	VM_BUG_ON_PAGE(!(pc->flags & PCG_MEM), oldpage);
+	VM_BUG_ON_PAGE(!(pc->flags & PCG_MEMSW), oldpage);
+	pc->flags &= ~(PCG_MEM | PCG_MEMSW);
+
+	if (PageTransHuge(oldpage)) {
+		nr_pages <<= compound_order(oldpage);
+		VM_BUG_ON_PAGE(!PageTransHuge(oldpage), oldpage);
+		VM_BUG_ON_PAGE(!PageTransHuge(newpage), newpage);
+	}
+
+	commit_charge(newpage, pc->mem_cgroup, nr_pages, lrucare);
+}
+
 /*
  * subsys_initcall() for memory controller.
  *
diff --git a/mm/memory.c b/mm/memory.c
index 3b95ee253c19..3a5019b5bb28 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1292,7 +1292,6 @@ static void unmap_page_range(struct mmu_gather *tlb,
 		details = NULL;
 
 	BUG_ON(addr >= end);
-	mem_cgroup_uncharge_start();
 	tlb_start_vma(tlb, vma);
 	pgd = pgd_offset(vma->vm_mm, addr);
 	do {
@@ -1302,7 +1301,6 @@ static void unmap_page_range(struct mmu_gather *tlb,
 		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
 	} while (pgd++, addr = next, addr != end);
 	tlb_end_vma(tlb, vma);
-	mem_cgroup_uncharge_end();
 }
 
 
diff --git a/mm/migrate.c b/mm/migrate.c
index 2a459675eeab..f2aa6b00d7f3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -780,11 +780,14 @@ static int move_to_new_page(struct page *newpage, struct page *page,
 		rc = fallback_migrate_page(mapping, newpage, page, mode);
 
 	if (rc != MIGRATEPAGE_SUCCESS) {
-		newpage->mapping = NULL;
+		if (!PageAnon(newpage))
+			newpage->mapping = NULL;
 	} else {
 		if (remap_swapcache)
 			remove_migration_ptes(page, newpage);
-		page->mapping = NULL;
+		if (!PageAnon(page))
+			page->mapping = NULL;
+		mem_cgroup_migrate(page, newpage, false);
 	}
 
 	unlock_page(newpage);
@@ -797,7 +800,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 {
 	int rc = -EAGAIN;
 	int remap_swapcache = 1;
-	struct mem_cgroup *mem;
 	struct anon_vma *anon_vma = NULL;
 
 	if (!trylock_page(page)) {
@@ -823,9 +825,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		lock_page(page);
 	}
 
-	/* charge against new page */
-	mem_cgroup_prepare_migration(page, newpage, &mem);
-
 	if (PageWriteback(page)) {
 		/*
 		 * Only in the case of a full synchronous migration is it
@@ -835,10 +834,10 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		 */
 		if (mode != MIGRATE_SYNC) {
 			rc = -EBUSY;
-			goto uncharge;
+			goto out_unlock;
 		}
 		if (!force)
-			goto uncharge;
+			goto out_unlock;
 		wait_on_page_writeback(page);
 	}
 	/*
@@ -874,7 +873,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 			 */
 			remap_swapcache = 0;
 		} else {
-			goto uncharge;
+			goto out_unlock;
 		}
 	}
 
@@ -887,7 +886,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		 * the page migration right away (proteced by page lock).
 		 */
 		rc = balloon_page_migrate(newpage, page, mode);
-		goto uncharge;
+		goto out_unlock;
 	}
 
 	/*
@@ -906,7 +905,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		VM_BUG_ON_PAGE(PageAnon(page), page);
 		if (page_has_private(page)) {
 			try_to_free_buffers(page);
-			goto uncharge;
+			goto out_unlock;
 		}
 		goto skip_unmap;
 	}
@@ -925,10 +924,7 @@ skip_unmap:
 	if (anon_vma)
 		put_anon_vma(anon_vma);
 
-uncharge:
-	mem_cgroup_end_migration(mem, page, newpage,
-				 (rc == MIGRATEPAGE_SUCCESS ||
-				  rc == MIGRATEPAGE_BALLOON_SUCCESS));
+out_unlock:
 	unlock_page(page);
 out:
 	return rc;
@@ -1787,7 +1783,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 	pg_data_t *pgdat = NODE_DATA(node);
 	int isolated = 0;
 	struct page *new_page = NULL;
-	struct mem_cgroup *memcg = NULL;
 	int page_lru = page_is_file_cache(page);
 	unsigned long mmun_start = address & HPAGE_PMD_MASK;
 	unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE;
@@ -1853,15 +1848,6 @@ fail_putback:
 		goto out_unlock;
 	}
 
-	/*
-	 * Traditional migration needs to prepare the memcg charge
-	 * transaction early to prevent the old page from being
-	 * uncharged when installing migration entries.  Here we can
-	 * save the potential rollback and start the charge transfer
-	 * only when migration is already known to end successfully.
-	 */
-	mem_cgroup_prepare_migration(page, new_page, &memcg);
-
 	orig_entry = *pmd;
 	entry = mk_pmd(new_page, vma->vm_page_prot);
 	entry = pmd_mkhuge(entry);
@@ -1889,14 +1875,10 @@ fail_putback:
 		goto fail_putback;
 	}
 
+	mem_cgroup_migrate(page, new_page, false);
+
 	page_remove_rmap(page);
 
-	/*
-	 * Finish the charge transaction under the page table lock to
-	 * prevent split_huge_page() from dividing up the charge
-	 * before it's fully transferred to the new page.
-	 */
-	mem_cgroup_end_migration(memcg, page, new_page, true);
 	spin_unlock(ptl);
 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 
diff --git a/mm/rmap.c b/mm/rmap.c
index b4b1d1424ab3..2aa912b0d434 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1083,7 +1083,6 @@ void page_remove_rmap(struct page *page)
 	if (unlikely(PageHuge(page)))
 		goto out;
 	if (anon) {
-		mem_cgroup_uncharge_page(page);
 		if (PageTransHuge(page))
 			__dec_zone_page_state(page,
 					      NR_ANON_TRANSPARENT_HUGEPAGES);
diff --git a/mm/shmem.c b/mm/shmem.c
index ea968bf84942..dc9eb434ea8e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -405,7 +405,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			pvec.pages, indices);
 		if (!pvec.nr)
 			break;
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -433,7 +432,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		cond_resched();
 		index++;
 	}
@@ -484,7 +482,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			pagevec_release(&pvec);
 			break;
 		}
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -511,7 +508,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		index++;
 	}
 
@@ -809,7 +805,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 	}
 
 	mutex_unlock(&shmem_swaplist_mutex);
-	swapcache_free(swap, NULL);
+	swapcache_free(swap);
 redirty:
 	set_page_dirty(page);
 	if (wbc->for_reclaim)
@@ -982,7 +978,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 		 */
 		oldpage = newpage;
 	} else {
-		mem_cgroup_replace_page_cache(oldpage, newpage);
+		mem_cgroup_migrate(oldpage, newpage, false);
 		lru_cache_add_anon(newpage);
 		*pagep = newpage;
 	}
diff --git a/mm/swap.c b/mm/swap.c
index a98f48626359..3074210f245d 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -62,6 +62,7 @@ static void __page_cache_release(struct page *page)
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
+	mem_cgroup_uncharge(page);
 }
 
 static void __put_single_page(struct page *page)
@@ -915,6 +916,8 @@ void release_pages(struct page **pages, int nr, bool cold)
 	struct lruvec *lruvec;
 	unsigned long uninitialized_var(flags);
 
+	mem_cgroup_uncharge_start();
+
 	for (i = 0; i < nr; i++) {
 		struct page *page = pages[i];
 
@@ -946,6 +949,7 @@ void release_pages(struct page **pages, int nr, bool cold)
 			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
 		}
+		mem_cgroup_uncharge(page);
 
 		/* Clear Active bit in case of parallel mark_page_accessed */
 		__ClearPageActive(page);
@@ -955,6 +959,8 @@ void release_pages(struct page **pages, int nr, bool cold)
 	if (zone)
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 
+	mem_cgroup_uncharge_end();
+
 	free_hot_cold_page_list(&pages_to_free, cold);
 }
 EXPORT_SYMBOL(release_pages);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 2972eee184a4..e160151da6b8 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -176,7 +176,7 @@ int add_to_swap(struct page *page, struct list_head *list)
 
 	if (unlikely(PageTransHuge(page)))
 		if (unlikely(split_huge_page_to_list(page, list))) {
-			swapcache_free(entry, NULL);
+			swapcache_free(entry);
 			return 0;
 		}
 
@@ -202,7 +202,7 @@ int add_to_swap(struct page *page, struct list_head *list)
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
 		 * clear SWAP_HAS_CACHE flag.
 		 */
-		swapcache_free(entry, NULL);
+		swapcache_free(entry);
 		return 0;
 	}
 }
@@ -225,7 +225,7 @@ void delete_from_swap_cache(struct page *page)
 	__delete_from_swap_cache(page);
 	spin_unlock_irq(&address_space->tree_lock);
 
-	swapcache_free(entry, page);
+	swapcache_free(entry);
 	page_cache_release(page);
 }
 
@@ -386,7 +386,7 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
 		 * clear SWAP_HAS_CACHE flag.
 		 */
-		swapcache_free(entry, NULL);
+		swapcache_free(entry);
 	} while (err != -ENOMEM);
 
 	if (new_page)
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 3882fcb04ad9..f7270063ef8f 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -866,16 +866,13 @@ void swap_free(swp_entry_t entry)
 /*
  * Called after dropping swapcache to decrease refcnt to swap entries.
  */
-void swapcache_free(swp_entry_t entry, struct page *page)
+void swapcache_free(swp_entry_t entry)
 {
 	struct swap_info_struct *p;
-	unsigned char count;
 
 	p = swap_info_get(entry);
 	if (p) {
-		count = swap_entry_free(p, entry, SWAP_HAS_CACHE);
-		if (page)
-			mem_cgroup_uncharge_swapcache(page, entry, count != 0);
+		swap_entry_free(p, entry, SWAP_HAS_CACHE);
 		spin_unlock(&p->lock);
 	}
 }
diff --git a/mm/truncate.c b/mm/truncate.c
index 6a78c814bebf..b352481c276d 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -281,7 +281,6 @@ void truncate_inode_pages_range(struct address_space *mapping,
 	while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
 			min(end - index, (pgoff_t)PAGEVEC_SIZE),
 			indices)) {
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -307,7 +306,6 @@ void truncate_inode_pages_range(struct address_space *mapping,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		cond_resched();
 		index++;
 	}
@@ -367,7 +365,6 @@ void truncate_inode_pages_range(struct address_space *mapping,
 			pagevec_release(&pvec);
 			break;
 		}
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -389,7 +386,6 @@ void truncate_inode_pages_range(struct address_space *mapping,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		index++;
 	}
 	cleancache_invalidate_inode(mapping);
@@ -488,7 +484,6 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 			indices)) {
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -517,7 +512,6 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		cond_resched();
 		index++;
 	}
@@ -548,7 +542,6 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
 	BUG_ON(page_has_private(page));
 	__delete_from_page_cache(page, NULL);
 	spin_unlock_irq(&mapping->tree_lock);
-	mem_cgroup_uncharge_cache_page(page);
 
 	if (mapping->a_ops->freepage)
 		mapping->a_ops->freepage(page);
@@ -597,7 +590,6 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 	while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
 			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 			indices)) {
-		mem_cgroup_uncharge_start();
 		for (i = 0; i < pagevec_count(&pvec); i++) {
 			struct page *page = pvec.pages[i];
 
@@ -650,7 +642,6 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
 		}
 		pagevec_remove_exceptionals(&pvec);
 		pagevec_release(&pvec);
-		mem_cgroup_uncharge_end();
 		cond_resched();
 		index++;
 	}
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a8ffe4e616fe..9a63d13739a6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -571,9 +571,10 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 
 	if (PageSwapCache(page)) {
 		swp_entry_t swap = { .val = page_private(page) };
+		mem_cgroup_swapout(page, swap);
 		__delete_from_swap_cache(page);
 		spin_unlock_irq(&mapping->tree_lock);
-		swapcache_free(swap, page);
+		swapcache_free(swap);
 	} else {
 		void (*freepage)(struct page *);
 		void *shadow = NULL;
@@ -594,7 +595,6 @@ static int __remove_mapping(struct address_space *mapping, struct page *page,
 			shadow = workingset_eviction(mapping, page);
 		__delete_from_page_cache(page, shadow);
 		spin_unlock_irq(&mapping->tree_lock);
-		mem_cgroup_uncharge_cache_page(page);
 
 		if (freepage != NULL)
 			freepage(page);
@@ -1097,6 +1097,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 */
 		__clear_page_locked(page);
 free_it:
+		mem_cgroup_uncharge(page);
 		nr_reclaimed++;
 
 		/*
@@ -1126,12 +1127,13 @@ keep:
 		list_add(&page->lru, &ret_pages);
 		VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page), page);
 	}
+	mem_cgroup_uncharge_end();
 
 	free_hot_cold_page_list(&free_pages, true);
 
 	list_splice(&ret_pages, page_list);
 	count_vm_events(PGACTIVATE, pgactivate);
-	mem_cgroup_uncharge_end();
+
 	*ret_nr_dirty += nr_dirty;
 	*ret_nr_congested += nr_congested;
 	*ret_nr_unqueued_dirty += nr_unqueued_dirty;
@@ -1429,6 +1431,8 @@ putback_inactive_pages(struct lruvec *lruvec, struct list_head *page_list)
 			__ClearPageActive(page);
 			del_page_from_lru_list(page, lruvec, lru);
 
+			mem_cgroup_uncharge(page);
+
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&zone->lru_lock);
 				(*get_compound_page_dtor(page))(page);
@@ -1652,6 +1656,8 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
 			__ClearPageActive(page);
 			del_page_from_lru_list(page, lruvec, lru);
 
+			mem_cgroup_uncharge(page);
+
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&zone->lru_lock);
 				(*get_compound_page_dtor(page))(page);
diff --git a/mm/zswap.c b/mm/zswap.c
index 008388fe7b0f..333d70c66093 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -502,7 +502,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry,
 		 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
 		 * clear SWAP_HAS_CACHE flag.
 		 */
-		swapcache_free(entry, NULL);
+		swapcache_free(entry);
 	} while (err != -ENOMEM);
 
 	if (new_page)
-- 
1.9.3

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