Re: [patch 2/4] mm: memcontrol: don't pass a NULL memcg to mem_cgroup_end_move()
From: Vladimir Davydov <hidden>
Date: 2014-10-22 06:52:26
Also in:
linux-mm, lkml
On Tue, Oct 21, 2014 at 04:21:34PM -0400, Johannes Weiner wrote:
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 <redacted>
Acked-by: Vladimir Davydov <redacted>
quoted hunk ↗ jump to hunk
--- mm/memcontrol.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1ff125d2a427..c1fe774d712a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -1452,14 +1452,8 @@ 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); - atomic_dec(&memcg->moving_account); - } + atomic_dec(&memcg_moving); + atomic_dec(&memcg->moving_account); } /*@@ -5383,7 +5377,8 @@ 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,-- 2.1.2