Commit ece35ca8 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: fix LRU accounting with THP 



memory cgroup's LRU stat should take care of size of pages because
Transparent Hugepage inserts hugepage into LRU.  If this value is the
number wrong, memory reclaim will not work well.

Note: only head page of THP's huge page is linked into LRU.

Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ca3e0214

mm/memcontrol.c

+18 −4
Original line number Diff line number Diff line
@@ -814,7 +814,8 @@ void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru) 
	 * removed from global LRU.

	 */

	mz = page_cgroup_zoneinfo(pc);

	MEM_CGROUP_ZSTAT(mz, lru) -= 1;

	/* huge page split is done under lru_lock. so, we have no races. */

	MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page);

	if (mem_cgroup_is_root(pc->mem_cgroup))

		return;

	VM_BUG_ON(list_empty(&pc->lru));
@@ -865,7 +866,8 @@ void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru) 
		return;



	mz = page_cgroup_zoneinfo(pc);

	MEM_CGROUP_ZSTAT(mz, lru) += 1;

	/* huge page split is done under lru_lock. so, we have no races. */

	MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page);

	SetPageCgroupAcctLRU(pc);

	if (mem_cgroup_is_root(pc->mem_cgroup))

		return;
@@ -2152,14 +2154,26 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail) 
	unsigned long flags;



	/*

	 * We have no races witch charge/uncharge but will have races with

	 * We have no races with charge/uncharge but will have races with

	 * page state accounting.

	 */

	move_lock_page_cgroup(head_pc, &flags);



	tail_pc->mem_cgroup = head_pc->mem_cgroup;

	smp_wmb(); /* see __commit_charge() */

	/* we don't need to copy all flags...*/

	if (PageCgroupAcctLRU(head_pc)) {

		enum lru_list lru;

		struct mem_cgroup_per_zone *mz;



		/*

		 * LRU flags cannot be copied because we need to add tail

		 *.page to LRU by generic call and our hook will be called.

		 * We hold lru_lock, then, reduce counter directly.

		 */

		lru = page_lru(head);

		mz = page_cgroup_zoneinfo(head_pc);

		MEM_CGROUP_ZSTAT(mz, lru) -= 1;

	}

	tail_pc->flags = head_pc->flags & ~PCGF_NOCOPY_AT_SPLIT;

	move_unlock_page_cgroup(head_pc, &flags);

}

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