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

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.

[ augment changelog]
Signed-off-by: default avatarVladimir Davydov <>
Cc: Johannes Weiner <>
Acked-by: default avatarMichal Hocko <>
Cc: Balbir Singh <>
Cc: KAMEZAWA Hiroyuki <>
Cc: Glauber Costa <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
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) ==
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