From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759256Ab0J1Pwb (ORCPT ); Thu, 28 Oct 2010 11:52:31 -0400 Received: from e2.ny.us.ibm.com ([32.97.182.142]:45459 "EHLO e2.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754724Ab0J1Pw1 (ORCPT ); Thu, 28 Oct 2010 11:52:27 -0400 Date: Thu, 28 Oct 2010 21:22:07 +0530 From: Balbir Singh To: Dan Carpenter , Daisuke Nishimura , KAMEZAWA Hiroyuki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [patch] memcg: null dereference on allocation failure Message-ID: <20101028155207.GB3769@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20101028111241.GC6062@bicker> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20101028111241.GC6062@bicker> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Dan Carpenter [2010-10-28 13:12:41]: > The original code had a null dereference if alloc_percpu() failed. > This was introduced in 711d3d2c9bc3 "memcg: cpu hotplug aware percpu > count updates" > > Signed-off-by: Dan Carpenter > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 9a99cfa..2efa8ea 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4208,15 +4208,17 @@ static struct mem_cgroup *mem_cgroup_alloc(void) > > memset(mem, 0, size); > mem->stat = alloc_percpu(struct mem_cgroup_stat_cpu); > - if (!mem->stat) { > - if (size < PAGE_SIZE) > - kfree(mem); > - else > - vfree(mem); > - mem = NULL; > - } > + if (!mem->stat) > + goto out_free; > spin_lock_init(&mem->pcp_counter_lock); > return mem; > + > +out_free: > + if (size < PAGE_SIZE) > + kfree(mem); > + else > + vfree(mem); > + return NULL; > } Good catch! Reviewed-by: Balbir Singh -- Three Cheers, Balbir