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Commit ce587e65 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: memcg: move pc lookup point to commit_charge() 



None of the callsites actually need the page_cgroup descriptor
themselves, so just pass the page and do the look up in there.

We already had two bugs (6568d4a9 'mm: memcg: update the correct soft
limit tree during migration' and 'memcg: fix Bad page state after
replace_page_cache') where the passed page and pc were not referring
to the same page frame.

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4e1c2b28

mm/memcontrol.c

+5 −12
Original line number Diff line number Diff line
@@ -2476,10 +2476,10 @@ struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page) 
static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,

				       struct page *page,

				       unsigned int nr_pages,

				       struct page_cgroup *pc,

				       enum charge_type ctype,

				       bool lrucare)

{

	struct page_cgroup *pc = lookup_page_cgroup(page);

	struct zone *uninitialized_var(zone);

	bool was_on_lru = false;

	bool anon;
@@ -2716,7 +2716,6 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, 
{

	struct mem_cgroup *memcg = NULL;

	unsigned int nr_pages = 1;

	struct page_cgroup *pc;

	bool oom = true;

	int ret;
@@ -2730,11 +2729,10 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm, 
		oom = false;

	}



	pc = lookup_page_cgroup(page);

	ret = __mem_cgroup_try_charge(mm, gfp_mask, nr_pages, &memcg, oom);

	if (ret == -ENOMEM)

		return ret;

	__mem_cgroup_commit_charge(memcg, page, nr_pages, pc, ctype, false);

	__mem_cgroup_commit_charge(memcg, page, nr_pages, ctype, false);

	return 0;

}
@@ -2831,16 +2829,13 @@ static void 
__mem_cgroup_commit_charge_swapin(struct page *page, struct mem_cgroup *memcg,

					enum charge_type ctype)

{

	struct page_cgroup *pc;



	if (mem_cgroup_disabled())

		return;

	if (!memcg)

		return;

	cgroup_exclude_rmdir(&memcg->css);



	pc = lookup_page_cgroup(page);

	__mem_cgroup_commit_charge(memcg, page, 1, pc, ctype, true);

	__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.
@@ -3298,14 +3293,13 @@ int mem_cgroup_prepare_migration(struct page *page, 
	 * 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().

	 */

	pc = lookup_page_cgroup(newpage);

	if (PageAnon(page))

		ctype = MEM_CGROUP_CHARGE_TYPE_MAPPED;

	else if (page_is_file_cache(page))

		ctype = MEM_CGROUP_CHARGE_TYPE_CACHE;

	else

		ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM;

	__mem_cgroup_commit_charge(memcg, newpage, 1, pc, ctype, false);

	__mem_cgroup_commit_charge(memcg, newpage, 1, ctype, false);

	return ret;

}
@@ -3392,8 +3386,7 @@ 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.

	 */

	pc = lookup_page_cgroup(newpage);

	__mem_cgroup_commit_charge(memcg, newpage, 1, pc, type, true);

	__mem_cgroup_commit_charge(memcg, newpage, 1, type, true);

}



#ifdef CONFIG_DEBUG_VM