From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 8FDEE6B0062 for ; Mon, 23 Nov 2009 02:02:15 -0500 (EST) Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp07.au.ibm.com (8.14.3/8.13.1) with ESMTP id nAN727Cj021522 for ; Mon, 23 Nov 2009 18:02:07 +1100 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id nAN725Ag1376432 for ; Mon, 23 Nov 2009 18:02:07 +1100 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id nAN724rJ022794 for ; Mon, 23 Nov 2009 18:02:05 +1100 Date: Mon, 23 Nov 2009 12:29:52 +0530 From: Balbir Singh Subject: Re: [PATCH -mmotm 5/5] memcg: recharge charges of anonymous swap Message-ID: <20091123065952.GR31961@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20091119132734.1757fc42.nishimura@mxp.nes.nec.co.jp> <20091119133120.0968626f.nishimura@mxp.nes.nec.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20091119133120.0968626f.nishimura@mxp.nes.nec.co.jp> Sender: owner-linux-mm@kvack.org To: Daisuke Nishimura Cc: linux-mm , Andrew Morton , KAMEZAWA Hiroyuki , Li Zefan , Paul Menage List-ID: * nishimura@mxp.nes.nec.co.jp [2009-11-19 13:31:20]: > This patch is another core part of this recharge-at-task-move feature. > It enables recharge of anonymous swaps. > > To move the charge of swap, we need to exchange swap_cgroup's record. > > In current implementation, swap_cgroup's record is protected by: > > - page lock: if the entry is on swap cache. > - swap_lock: if the entry is not on swap cache. > > This works well in usual swap-in/out activity. > > But this behavior make charge migration of swap check many conditions to > exchange swap_cgroup's record safely. > > So I changed modification of swap_cgroup's recored(swap_cgroup_record()) > to use xchg, and define a new function to cmpxchg swap_cgroup's record. > > This patch also enables recharge of non pte_present but not uncharged swap > caches, which can be exist on swap-out path, by getting the target pages via > find_get_page() as do_mincore() does. > > Changelog: 2009/11/19 > - in can_attach(), instead of parsing the page table, make use of per process > mm_counter(swap_usage). > Changelog: 2009/11/06 > - drop support for shmem's swap(revisit in future). > - add mem_cgroup_count_swap_user() to prevent moving charges of swaps used by > multiple processes(revisit in future). > Changelog: 2009/09/24 > - do no swap-in in moving swap account any more. > - add support for shmem's swap. > > Signed-off-by: Daisuke Nishimura > --- > include/linux/page_cgroup.h | 2 + > include/linux/swap.h | 1 + > mm/memcontrol.c | 150 ++++++++++++++++++++++++++++++++++--------- > mm/page_cgroup.c | 35 ++++++++++- > mm/swapfile.c | 31 +++++++++ > 5 files changed, 186 insertions(+), 33 deletions(-) > > diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h > index b0e4eb1..30b0813 100644 > --- a/include/linux/page_cgroup.h > +++ b/include/linux/page_cgroup.h > @@ -118,6 +118,8 @@ static inline void __init page_cgroup_init_flatmem(void) > #include > > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP > +extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, > + unsigned short old, unsigned short new); > extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id); > extern unsigned short lookup_swap_cgroup(swp_entry_t ent); > extern int swap_cgroup_swapon(int type, unsigned long max_pages); > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 9f0ca32..2a3209e 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -355,6 +355,7 @@ static inline void disable_swap_token(void) > #ifdef CONFIG_CGROUP_MEM_RES_CTLR > extern void > mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout); > +extern int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep); > #else > static inline void > mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 3a07383..ea00a93 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -33,6 +33,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -2230,6 +2231,49 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent) > } > rcu_read_unlock(); > } > + > +/** > + * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record. > + * @entry: swap entry to be moved > + * @from: mem_cgroup which the entry is moved from > + * @to: mem_cgroup which the entry is moved to > + * > + * It successes only when the swap_cgroup's record for this entry is the same ^^^^^^^^^ Should be succeeds > + * as the mem_cgroup's id of @from. > + * > + * Returns 0 on success, -EINVAL on failure. > + * > + * The caller must have called __mem_cgroup_try_charge on @to. > + */ > +static int mem_cgroup_move_swap_account(swp_entry_t entry, > + struct mem_cgroup *from, struct mem_cgroup *to) > +{ > + unsigned short old_id, new_id; > + > + old_id = css_id(&from->css); > + new_id = css_id(&to->css); > + > + if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) { > + if (!mem_cgroup_is_root(from)) > + res_counter_uncharge(&from->memsw, PAGE_SIZE); > + mem_cgroup_swap_statistics(from, false); > + mem_cgroup_put(from); > + > + if (!mem_cgroup_is_root(to)) > + res_counter_uncharge(&to->res, PAGE_SIZE); Uncharge from "to" as well? Need more comments to understand the code. > + mem_cgroup_swap_statistics(to, true); > + mem_cgroup_get(to); > + > + return 0; > + } > + return -EINVAL; > +} > +#else > +static inline int mem_cgroup_move_swap_account(swp_entry_t entry, > + struct mem_cgroup *from, struct mem_cgroup *to) > +{ > + return -EINVAL; > +} > #endif > > /* > @@ -3477,8 +3521,10 @@ static int mem_cgroup_prepare_recharge(struct mm_struct *mm) > bool recharge_anon = test_bit(RECHARGE_TYPE_ANON, > &recharge.to->recharge_at_immigrate); > > - if (recharge_anon) > + if (recharge_anon) { > prepare += get_mm_counter(mm, anon_rss); > + prepare += get_mm_counter(mm, swap_usage); > + } Does this logic handle shared pages correctly? Could you please check. > > while (!ret && prepare--) { > if (!count--) { > @@ -3553,66 +3599,99 @@ static void mem_cgroup_cancel_attach(struct cgroup_subsys *ss, > * @vma: the vma the pte to be checked belongs > * @addr: the address corresponding to the pte to be checked > * @ptent: the pte to be checked > - * @target: the pointer the target page will be stored > + * @target: the pointer the target page or swap entry will be stored > * > * Returns > * 0(RECHARGE_TARGET_NONE): if the pte is not a target for recharge. > * 1(RECHARGE_TARGET_PAGE): if the page corresponding to this pte is a target > * for recharge. if @target is not NULL, the page is stored in target->page > * with extra refcnt got(Callers should handle it). > + * 2(MIGRATION_TARGET_SWAP): if the swap entry corresponding to this pte is a > + * target for charge migration. if @target is not NULL, the entry is stored > + * in target->ent. > * > * Called with pte lock held. > */ > -/* We add a new member later. */ > union recharge_target { > struct page *page; > + swp_entry_t ent; > }; > > -/* We add a new type later. */ > enum recharge_target_type { > RECHARGE_TARGET_NONE, /* not used */ > RECHARGE_TARGET_PAGE, > + RECHARGE_TARGET_SWAP, > }; > > static int is_target_pte_for_recharge(struct vm_area_struct *vma, > unsigned long addr, pte_t ptent, union recharge_target *target) > { > - struct page *page; > + struct page *page = NULL; > struct page_cgroup *pc; > + swp_entry_t ent = { .val = 0 }; > + int user = 0; > int ret = 0; > bool recharge_anon = test_bit(RECHARGE_TYPE_ANON, > &recharge.to->recharge_at_immigrate); > > - if (!pte_present(ptent)) > - return 0; > + if (!pte_present(ptent)) { > + /* TODO: handle swap of shmes/tmpfs */ > + if (pte_none(ptent) || pte_file(ptent)) > + return 0; > + else if (is_swap_pte(ptent)) { > + ent = pte_to_swp_entry(ptent); > + if (!recharge_anon || non_swap_entry(ent)) > + return 0; > + user = mem_cgroup_count_swap_user(ent, &page); > + } > + } else { > + page = vm_normal_page(vma, addr, ptent); > + if (!page || !page_mapped(page)) > + return 0; > + /* > + * TODO: We don't recharge file(including shmem/tmpfs) pages > + * for now. > + */ > + if (!recharge_anon || !PageAnon(page)) > + return 0; > + if (!get_page_unless_zero(page)) > + return 0; > + user = page_mapcount(page); > + } > > - page = vm_normal_page(vma, addr, ptent); > - if (!page || !page_mapped(page)) > - return 0; > - /* TODO: We don't recharge file(including shmem/tmpfs) pages for now. */ > - if (!recharge_anon || !PageAnon(page)) > - return 0; > - /* > - * TODO: We don't recharge shared(used by multiple processes) pages > - * for now. > - */ > - if (page_mapcount(page) > 1) > - return 0; > - if (!get_page_unless_zero(page)) > + if (user > 1) { users or usage_count would be better name. > + /* > + * TODO: We don't recharge shared(used by multiple processes) > + * pages for now. > + */ > + if (page) > + put_page(page); > return 0; > - > - 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. > - */ > - if (PageCgroupUsed(pc)) { > - ret = RECHARGE_TARGET_PAGE; > - target->page = page; > } > > - if (!ret) > - put_page(page); > + 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. > + */ > + if (PageCgroupUsed(pc)) { > + ret = RECHARGE_TARGET_PAGE; > + target->page = page; > + } > + if (!ret) > + put_page(page); > + } > + /* fall throught */ should be through > + if (ent.val && do_swap_account && !ret) { > + /* > + * mem_cgroup_move_swap_account() checks the entry is valid or > + * not. > + */ > + ret = RECHARGE_TARGET_SWAP; > + target->ent = ent; > + } > > return ret; > } > @@ -3634,6 +3713,7 @@ retry: > int type; > struct page *page; > struct page_cgroup *pc; > + swp_entry_t ent; > > if (!recharge.precharge) > break; > @@ -3654,6 +3734,14 @@ retry: > put: /* is_target_pte_for_recharge() gets the page */ > put_page(page); > break; > + case RECHARGE_TARGET_SWAP: > + ent = target.ent; > + if (!mem_cgroup_move_swap_account(ent, > + recharge.from, recharge.to)) { > + css_put(&recharge.to->css); > + recharge.precharge--; > + } > + break; > default: > break; > } > diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c > index 3d535d5..213b0ee 100644 > --- a/mm/page_cgroup.c > +++ b/mm/page_cgroup.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > > static void __meminit > __init_page_cgroup(struct page_cgroup *pc, unsigned long pfn) > @@ -335,6 +336,37 @@ not_enough_page: > } > > /** > + * swap_cgroup_cmpxchg - cmpxchg mem_cgroup's id for this swp_entry. > + * @end: swap entry to be cmpxchged > + * @old: old id > + * @new: new id > + * > + * Returns old id at success, 0 at failure. > + * (There is no mem_cgroup useing 0 as its id) > + */ > +unsigned short swap_cgroup_cmpxchg(swp_entry_t ent, > + unsigned short old, unsigned short new) > +{ > + int type = swp_type(ent); > + unsigned long offset = swp_offset(ent); > + unsigned long idx = offset / SC_PER_PAGE; > + unsigned long pos = offset & SC_POS_MASK; > + struct swap_cgroup_ctrl *ctrl; > + struct page *mappage; > + struct swap_cgroup *sc; > + > + ctrl = &swap_cgroup_ctrl[type]; > + > + mappage = ctrl->map[idx]; > + sc = page_address(mappage); > + sc += pos; > + if (cmpxchg(&sc->id, old, new) == old) > + return old; > + else > + return 0; > +} > + > +/** > * swap_cgroup_record - record mem_cgroup for this swp_entry. > * @ent: swap entry to be recorded into > * @mem: mem_cgroup to be recorded > @@ -358,8 +390,7 @@ unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id) > mappage = ctrl->map[idx]; > sc = page_address(mappage); > sc += pos; > - old = sc->id; > - sc->id = id; > + old = xchg(&sc->id, id); > > return old; > } > diff --git a/mm/swapfile.c b/mm/swapfile.c > index f32d716..cc2e859 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -719,6 +719,37 @@ int free_swap_and_cache(swp_entry_t entry) > return p != NULL; > } > > +#ifdef CONFIG_CGROUP_MEM_RES_CTLR > +/** > + * mem_cgroup_count_swap_user - count the user of a swap entry > + * @ent: the swap entry to be checked > + * @pagep: the pointer for the swap cache page of the entry to be stored > + * > + * Returns the number of the user of the swap entry. The number is valid only > + * for swaps of anonymous pages. > + * If the entry is found on swap cache, the page is stored to pagep with > + * refcount of it being incremented. > + */ > +int mem_cgroup_count_swap_user(swp_entry_t ent, struct page **pagep) > +{ > + struct page *page; > + struct swap_info_struct *p; > + int count = 0; > + > + page = find_get_page(&swapper_space, ent.val); > + if (page) > + count += page_mapcount(page); > + p = swap_info_get(ent); > + if (p) { > + count += swap_count(p->swap_map[swp_offset(ent)]); > + spin_unlock(&swap_lock); > + } > + > + *pagep = page; > + return count; > +} > +#endif > + > #ifdef CONFIG_HIBERNATION > /* > * Find the swap type that corresponds to given device (if any). > -- > 1.5.6.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org