Commit 1c98dd90 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

memcg: fix kmem_account_flags check in memcg_can_account_kmem()



We should start kmem accounting for a memory cgroup only after both its
kmem limit is set (KMEM_ACCOUNTED_ACTIVE) and related call sites are
patched (KMEM_ACCOUNTED_ACTIVATED).  Currently memcg_can_account_kmem()
allows kmem accounting even if only one of the conditions is true.  Fix
it.

This means that a page might get charged by memcg_kmem_newpage_charge
which would see its static key patched already but
memcg_kmem_commit_charge would still see it unpatched and so the charge
won't be committed.  The result would be charge inconsistency
(page_cgroup not marked as PageCgroupUsed) and the charge would leak
because __memcg_kmem_uncharge_pages would ignore it.

[mhocko@suse.cz: augment changelog]
Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Glauber Costa <glommer@parallels.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b2f3eebe
......@@ -2959,7 +2959,8 @@ static DEFINE_MUTEX(set_limit_mutex);
static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
{
return !mem_cgroup_disabled() && !mem_cgroup_is_root(memcg) &&
(memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK);
(memcg->kmem_account_flags & KMEM_ACCOUNTED_MASK) ==
KMEM_ACCOUNTED_MASK;
}
/*
......
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