[PATCH 2/2] memcg: add per cgroup dirty pages accounting

[Sha Zhengju <handai.szj@gmail.com>]

This patch adds memcg routines to count dirty pages. I notice that
the list has talked about per-cgroup dirty page limiting
(http://lwn.net/Articles/455341/) before, but it did not get merged.
I've no idea how is this going now, but maybe we can add per cgroup
dirty pages accounting first. This allows the memory controller to
maintain an accurate view of the amount of its memory that is dirty
and can provide some infomation while group's direct reclaim is working.

After commit 89c06bd5 (memcg: use new logic for page stat accounting),
we do not need per page_cgroup flag anymore and can directly use
struct page flag.


Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
---
 include/linux/memcontrol.h |    1 +
 mm/filemap.c               |    1 +
 mm/memcontrol.c            |   32 +++++++++++++++++++++++++-------
 mm/page-writeback.c        |    2 ++
 mm/truncate.c              |    1 +
 5 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a337c2e..8154ade 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -39,6 +39,7 @@ enum mem_cgroup_stat_index {
 	MEM_CGROUP_STAT_FILE_MAPPED,  /* # of pages charged as file rss */
 	MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
 	MEM_CGROUP_STAT_DATA, /* end of data requires synchronization */
+	MEM_CGROUP_STAT_FILE_DIRTY,  /* # of dirty pages in page cache */
 	MEM_CGROUP_STAT_NSTATS,
 };
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 79c4b2b..5b5c121 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -141,6 +141,7 @@ void __delete_from_page_cache(struct page *page)
 	 * having removed the page entirely.
 	 */
 	if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
+		mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_DIRTY);
 		dec_zone_page_state(page, NR_FILE_DIRTY);
 		dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
 	}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9102b8c..d200ad1 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2548,6 +2548,18 @@ void mem_cgroup_split_huge_fixup(struct page *head)
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+static inline
+void mem_cgroup_move_account_page_stat(struct mem_cgroup *from,
+					struct mem_cgroup *to,
+					enum mem_cgroup_stat_index idx)
+{
+	/* Update stat data for mem_cgroup */
+	preempt_disable();
+	__this_cpu_dec(from->stat->count[idx]);
+	__this_cpu_inc(to->stat->count[idx]);
+	preempt_enable();
+}
+
 /**
  * mem_cgroup_move_account - move account of the page
  * @page: the page
@@ -2597,13 +2609,14 @@ static int mem_cgroup_move_account(struct page *page,
 
 	move_lock_mem_cgroup(from, &flags);
 
-	if (!anon && page_mapped(page)) {
-		/* Update mapped_file data for mem_cgroup */
-		preempt_disable();
-		__this_cpu_dec(from->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
-		__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);
-		preempt_enable();
-	}
+	if (!anon && page_mapped(page))
+		mem_cgroup_move_account_page_stat(from, to,
+					MEM_CGROUP_STAT_FILE_MAPPED);
+
+	if (PageDirty(page))
+		mem_cgroup_move_account_page_stat(from, to,
+					MEM_CGROUP_STAT_FILE_DIRTY);
+
 	mem_cgroup_charge_statistics(from, anon, -nr_pages);
 	if (uncharge)
 		/* This is not "cancel", but cancel_charge does all we need. */
@@ -4023,6 +4036,7 @@ enum {
 	MCS_SWAP,
 	MCS_PGFAULT,
 	MCS_PGMAJFAULT,
+	MCS_FILE_DIRTY,
 	MCS_INACTIVE_ANON,
 	MCS_ACTIVE_ANON,
 	MCS_INACTIVE_FILE,
@@ -4047,6 +4061,7 @@ struct {
 	{"swap", "total_swap"},
 	{"pgfault", "total_pgfault"},
 	{"pgmajfault", "total_pgmajfault"},
+	{"dirty", "total_dirty"},
 	{"inactive_anon", "total_inactive_anon"},
 	{"active_anon", "total_active_anon"},
 	{"inactive_file", "total_inactive_file"},
@@ -4080,6 +4095,9 @@ mem_cgroup_get_local_stat(struct mem_cgroup *memcg, struct mcs_total_stat *s)
 	val = mem_cgroup_read_events(memcg, MEM_CGROUP_EVENTS_PGMAJFAULT);
 	s->stat[MCS_PGMAJFAULT] += val;
 
+	val = mem_cgroup_read_stat(memcg, MEM_CGROUP_STAT_FILE_DIRTY);
+	s->stat[MCS_FILE_DIRTY] += val * PAGE_SIZE;
+
 	/* per zone stat */
 	val = mem_cgroup_nr_lru_pages(memcg, BIT(LRU_INACTIVE_ANON));
 	s->stat[MCS_INACTIVE_ANON] += val * PAGE_SIZE;
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 26adea8..b17c692 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1936,6 +1936,7 @@ int __set_page_dirty_no_writeback(struct page *page)
 void account_page_dirtied(struct page *page, struct address_space *mapping)
 {
 	if (mapping_cap_account_dirty(mapping)) {
+		mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_DIRTY);
 		__inc_zone_page_state(page, NR_FILE_DIRTY);
 		__inc_zone_page_state(page, NR_DIRTIED);
 		__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
@@ -2155,6 +2156,7 @@ int clear_page_dirty_for_io(struct page *page)
 		 * for more comments.
 		 */
 		if (TestClearPageDirty(page)) {
+			mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_DIRTY);
 			dec_zone_page_state(page, NR_FILE_DIRTY);
 			dec_bdi_stat(mapping->backing_dev_info,
 					BDI_RECLAIMABLE);
diff --git a/mm/truncate.c b/mm/truncate.c
index 61a183b..fe8363e 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -76,6 +76,7 @@ void cancel_dirty_page(struct page *page, unsigned int account_size)
 	if (TestClearPageDirty(page)) {
 		struct address_space *mapping = page->mapping;
 		if (mapping && mapping_cap_account_dirty(mapping)) {
+			mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_DIRTY);
 			dec_zone_page_state(page, NR_FILE_DIRTY);
 			dec_bdi_stat(mapping->backing_dev_info,
 					BDI_RECLAIMABLE);
-- 
1.7.1

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