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| author | Johannes Weiner <hannes@cmpxchg.org> | 2014-12-10 15:44:08 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-10 17:41:07 -0800 |
| commit | 4e2f245d38ba86e3922c6c188fe4a0d0688aed88 (patch) | |
| tree | 8d4f91042e2ede102bd94236543f5cd5a97a5592 /mm/memcontrol.c | |
| parent | 354a4783a2ee5ba1cb5a1442cca8ecd4c0ac6d66 (diff) | |
| download | lwn-4e2f245d38ba86e3922c6c188fe4a0d0688aed88.tar.gz lwn-4e2f245d38ba86e3922c6c188fe4a0d0688aed88.zip | |
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/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 10 |
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, |