From: Johannes Weiner <hannes@cmpxchg.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>,
Michal Hocko <mhocko@suse.cz>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [patch] mm: memcontrol: don't pass a NULL memcg to mem_cgroup_end_move()
Date: Thu, 23 Oct 2014 10:33:50 -0400 [thread overview]
Message-ID: <1414074830-14623-1-git-send-email-hannes@cmpxchg.org> (raw)
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>
---
mm/memcontrol.c | 10 +++-------
1 file 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,
--
2.1.2
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next reply other threads:[~2014-10-23 14:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-23 14:33 Johannes Weiner [this message]
2014-10-23 15:13 ` Michal Hocko
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