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authorJohannes Weiner <hannes@cmpxchg.org>2014-12-10 15:44:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:07 -0800
commit4e2f245d38ba86e3922c6c188fe4a0d0688aed88 (patch)
tree8d4f91042e2ede102bd94236543f5cd5a97a5592 /mm
parent354a4783a2ee5ba1cb5a1442cca8ecd4c0ac6d66 (diff)
downloadlinux-4e2f245d38ba86e3922c6c188fe4a0d0688aed88.tar.bz2
mm: memcontrol: don't pass a NULL memcg to mem_cgroup_end_move()
mem_cgroup_end_move() checks if the passed memcg is NULL, along with a lengthy comment to explain why this seemingly non-sensical situation is even possible. Check in cancel_attach() itself whether can_attach() set up the move context or not, it's a lot more obvious from there. Then remove the check and comment in mem_cgroup_end_move(). Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov@parallels.com> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memcontrol.c10
1 files changed, 3 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a5c9aa4688e8..3cd4f1e0bfb3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1469,12 +1469,7 @@ static void mem_cgroup_start_move(struct mem_cgroup *memcg)
static void mem_cgroup_end_move(struct mem_cgroup *memcg)
{
- /*
- * Now, mem_cgroup_clear_mc() may call this function with NULL.
- * We check NULL in callee rather than caller.
- */
- if (memcg)
- atomic_dec(&memcg->moving_account);
+ atomic_dec(&memcg->moving_account);
}
/*
@@ -5489,7 +5484,8 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset)
{
- mem_cgroup_clear_mc();
+ if (mc.to)
+ mem_cgroup_clear_mc();
}
static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,