From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id E14D590014E for ; Mon, 1 Aug 2011 08:12:29 -0400 (EDT) Date: Mon, 1 Aug 2011 14:12:22 +0200 From: Michal Hocko Subject: Re: [patch]mm: fix a memcg warning Message-ID: <20110801121222.GB25251@tiehlicka.suse.cz> References: <1312180878.15392.427.camel@sli10-conroe> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1312180878.15392.427.camel@sli10-conroe> Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: Andrew Morton , linux-mm , KAMEZAWA Hiroyuki On Mon 01-08-11 14:41:18, Shaohua Li wrote: > I get below warning: > BUG: using smp_processor_id() in preemptible [00000000] code: bash/739 > caller is drain_local_stock+0x1a/0x55 > Pid: 739, comm: bash Tainted: G W 3.0.0+ #255 > Call Trace: > [] debug_smp_processor_id+0xc2/0xdc > [] drain_local_stock+0x1a/0x55 > [] drain_all_stock+0x98/0x13a > [] mem_cgroup_force_empty+0xa3/0x27a > [] ? sys_close+0x38/0x138 > [] ? environ_read+0x1d/0x159 > [] mem_cgroup_force_empty_write+0x17/0x19 > [] cgroup_file_write+0xa8/0xba > [] vfs_write+0xb3/0x138 > [] sys_write+0x4a/0x71 > [] ? sys_close+0xf0/0x138 > [] system_call_fastpath+0x16/0x1b > > drain_local_stock() should be run with preempt disabled. Ahh, yes. This got in with d1a05b69 (memcg: do not try to drain per-cpu caches without pages) which started calling drain_local_stock directly rather than from a kernel thread. > Signed-off-by: Shaohua Li Acked-by: Michal Hocko Thanks for catching this. > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 5f84d23..11d5671 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2169,13 +2169,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync) > > /* Notify other cpus that system-wide "drain" is running */ > get_online_cpus(); > - /* > - * Get a hint for avoiding draining charges on the current cpu, > - * which must be exhausted by our charging. It is not required that > - * this be a precise check, so we use raw_smp_processor_id() instead of > - * getcpu()/putcpu(). > - */ > - curcpu = raw_smp_processor_id(); > + curcpu = get_cpu(); > for_each_online_cpu(cpu) { > struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu); > struct mem_cgroup *mem; > @@ -2192,6 +2186,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync) > schedule_work_on(cpu, &stock->work); > } > } > + put_cpu(); > > if (!sync) > goto out; > > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: email@kvack.org -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org