From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f181.google.com (mail-lb0-f181.google.com [209.85.217.181]) by kanga.kvack.org (Postfix) with ESMTP id B89036B008A for ; Thu, 23 Oct 2014 10:33:55 -0400 (EDT) Received: by mail-lb0-f181.google.com with SMTP id l4so930647lbv.26 for ; Thu, 23 Oct 2014 07:33:55 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id dl8si2882910lad.68.2014.10.23.07.33.53 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 23 Oct 2014 07:33:54 -0700 (PDT) From: Johannes Weiner Subject: [patch] mm: memcontrol: don't pass a NULL memcg to mem_cgroup_end_move() Date: Thu, 23 Oct 2014 10:33:50 -0400 Message-Id: <1414074830-14623-1-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Vladimir Davydov , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org 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 Acked-by: Vladimir Davydov --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org