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 DC4966B006C for ; Fri, 24 Oct 2014 09:49:56 -0400 (EDT) Received: by mail-lb0-f181.google.com with SMTP id l4so2642907lbv.12 for ; Fri, 24 Oct 2014 06:49:56 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id y9si7193884lbr.1.2014.10.24.06.49.54 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Oct 2014 06:49:55 -0700 (PDT) From: Johannes Weiner Subject: [patch 2/3] mm: memcontrol: pull the NULL check from __mem_cgroup_same_or_subtree() Date: Fri, 24 Oct 2014 09:49:48 -0400 Message-Id: <1414158589-26094-2-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1414158589-26094-1-git-send-email-hannes@cmpxchg.org> References: <1414158589-26094-1-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michal Hocko , Vladimir Davydov , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org The NULL in mm_match_cgroup() comes from a possibly exiting mm->owner. It makes a lot more sense to check where it's looked up, rather than check for it in __mem_cgroup_same_or_subtree() where it's unexpected. No other callsite passes NULL to __mem_cgroup_same_or_subtree(). Signed-off-by: Johannes Weiner --- include/linux/memcontrol.h | 5 +++-- mm/memcontrol.c | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index ea007615e8f9..e32ab948f589 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -83,11 +83,12 @@ static inline bool mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *memcg) { struct mem_cgroup *task_memcg; - bool match; + bool match = false; rcu_read_lock(); task_memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); - match = __mem_cgroup_same_or_subtree(memcg, task_memcg); + if (task_memcg) + match = __mem_cgroup_same_or_subtree(memcg, task_memcg); rcu_read_unlock(); return match; } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index bdf8520979cf..15b1c5110a8f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1316,7 +1316,7 @@ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg, { if (root_memcg == memcg) return true; - if (!root_memcg->use_hierarchy || !memcg) + if (!root_memcg->use_hierarchy) return false; return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup); } -- 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