Commit 4e2f245d authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds

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: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 354a4783
...@@ -1469,11 +1469,6 @@ static void mem_cgroup_start_move(struct mem_cgroup *memcg) ...@@ -1469,11 +1469,6 @@ static void mem_cgroup_start_move(struct mem_cgroup *memcg)
static void mem_cgroup_end_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);
} }
...@@ -5489,6 +5484,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css, ...@@ -5489,6 +5484,7 @@ static int mem_cgroup_can_attach(struct cgroup_subsys_state *css,
static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css, static void mem_cgroup_cancel_attach(struct cgroup_subsys_state *css,
struct cgroup_taskset *tset) struct cgroup_taskset *tset)
{ {
if (mc.to)
mem_cgroup_clear_mc(); mem_cgroup_clear_mc();
} }
......
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