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Commit 987eba66 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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memcg: fix rmdir, force_empty with THP 



Now, when THP is enabled, memcg's rmdir() function is broken because
move_account() for THP page is not supported.

This will cause account leak or -EBUSY issue at rmdir().
This patch fixes the issue by supporting move_account() THP pages.

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 ece35ca8

mm/memcontrol.c

+26 −11
Original line number Diff line number Diff line
@@ -2197,8 +2197,11 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail) 
 */



static void __mem_cgroup_move_account(struct page_cgroup *pc,

	struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)

	struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge,

	int charge_size)

{

	int nr_pages = charge_size >> PAGE_SHIFT;



	VM_BUG_ON(from == to);

	VM_BUG_ON(PageLRU(pc->page));

	VM_BUG_ON(!page_is_cgroup_locked(pc));
@@ -2212,14 +2215,14 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc, 
		__this_cpu_inc(to->stat->count[MEM_CGROUP_STAT_FILE_MAPPED]);

		preempt_enable();

	}

	mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -1);

	mem_cgroup_charge_statistics(from, PageCgroupCache(pc), -nr_pages);

	if (uncharge)

		/* This is not "cancel", but cancel_charge does all we need. */

		mem_cgroup_cancel_charge(from, PAGE_SIZE);

		mem_cgroup_cancel_charge(from, charge_size);



	/* caller should have done css_get */

	pc->mem_cgroup = to;

	mem_cgroup_charge_statistics(to, PageCgroupCache(pc), 1);

	mem_cgroup_charge_statistics(to, PageCgroupCache(pc), nr_pages);

	/*

	 * We charges against "to" which may not have any tasks. Then, "to"

	 * can be under rmdir(). But in current implementation, caller of
@@ -2234,15 +2237,19 @@ static void __mem_cgroup_move_account(struct page_cgroup *pc, 
 * __mem_cgroup_move_account()

 */

static int mem_cgroup_move_account(struct page_cgroup *pc,

		struct mem_cgroup *from, struct mem_cgroup *to, bool uncharge)

		struct mem_cgroup *from, struct mem_cgroup *to,

		bool uncharge, int charge_size)

{

	int ret = -EINVAL;

	unsigned long flags;



	if ((charge_size > PAGE_SIZE) && !PageTransHuge(pc->page))

		return -EBUSY;



	lock_page_cgroup(pc);

	if (PageCgroupUsed(pc) && pc->mem_cgroup == from) {

		move_lock_page_cgroup(pc, &flags);

		__mem_cgroup_move_account(pc, from, to, uncharge);

		__mem_cgroup_move_account(pc, from, to, uncharge, charge_size);

		move_unlock_page_cgroup(pc, &flags);

		ret = 0;

	}
@@ -2267,6 +2274,8 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc, 
	struct cgroup *cg = child->css.cgroup;

	struct cgroup *pcg = cg->parent;

	struct mem_cgroup *parent;

	int charge = PAGE_SIZE;

	unsigned long flags;

	int ret;



	/* Is ROOT ? */
@@ -2278,17 +2287,23 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc, 
		goto out;

	if (isolate_lru_page(page))

		goto put;

	/* The page is isolated from LRU and we have no race with splitting */

	charge = PAGE_SIZE << compound_order(page);



	parent = mem_cgroup_from_cont(pcg);

	ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false,

				      PAGE_SIZE);

	ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false, charge);

	if (ret || !parent)

		goto put_back;



	ret = mem_cgroup_move_account(pc, child, parent, true);

	if (charge > PAGE_SIZE)

		flags = compound_lock_irqsave(page);



	ret = mem_cgroup_move_account(pc, child, parent, true, charge);

	if (ret)

		mem_cgroup_cancel_charge(parent, PAGE_SIZE);

		mem_cgroup_cancel_charge(parent, charge);

put_back:

	if (charge > PAGE_SIZE)

		compound_unlock_irqrestore(page, flags);

	putback_lru_page(page);

put:

	put_page(page);
@@ -4868,7 +4883,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd, 
				goto put;

			pc = lookup_page_cgroup(page);

			if (!mem_cgroup_move_account(pc,

						mc.from, mc.to, false)) {

					mc.from, mc.to, false, PAGE_SIZE)) {

				mc.precharge--;

				/* we uncharge from mc.from later. */

				mc.moved_charge++;