From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754719AbcE3LWX (ORCPT ); Mon, 30 May 2016 07:22:23 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:32971 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754200AbcE3LWV (ORCPT ); Mon, 30 May 2016 07:22:21 -0400 Date: Mon, 30 May 2016 13:22:18 +0200 From: Michal Hocko To: Wenwei Tao Cc: Wenwei Tao , hannes@cmpxchg.org, vdavydov@virtuozzo.com, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/memcontrol.c: add memory allocation result check Message-ID: <20160530112218.GS22928@dhcp22.suse.cz> References: <1464597951-2976-1-git-send-email-wwtao0320@163.com> <20160530085311.GM22928@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 30-05-16 17:28:40, Wenwei Tao wrote: > I think explicit BUG_ON may make the debug easier, since it can point > out the wrong line. Does it? NULL ptr dereferencec 6 lines below sounds pretty close to me. I am not nacking this patch I just think it doesn't add much. If others think it will be useful I will not object. > 2016-05-30 16:53 GMT+08:00 Michal Hocko : > > On Mon 30-05-16 16:45:51, Wenwei Tao wrote: > >> From: Wenwei Tao > >> > >> The mem_cgroup_tree_per_node allocation might fail, > >> check that before continue the memcg init. Since it > >> is in the init phase, trigger the panic if that failure > >> happens. > > > > We would blow up in the very same function so what is the point of the > > explicit BUG_ON? > > > >> Signed-off-by: Wenwei Tao > >> --- > >> mm/memcontrol.c | 1 + > >> 1 file changed, 1 insertion(+) > >> > >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c > >> index 925b431..6385c62 100644 > >> --- a/mm/memcontrol.c > >> +++ b/mm/memcontrol.c > >> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void) > >> > >> rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, > >> node_online(node) ? node : NUMA_NO_NODE); > >> + BUG_ON(!rtpn); > >> > >> for (zone = 0; zone < MAX_NR_ZONES; zone++) { > >> struct mem_cgroup_tree_per_zone *rtpz; > >> -- > >> 1.8.3.1 > >> > >> > >> -- > >> 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 > > > > -- > > Michal Hocko > > SUSE Labs > > -- > 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 -- Michal Hocko SUSE Labs