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 8E284900138 for ; Wed, 17 Aug 2011 20:31:45 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 260013EE0AE for ; Thu, 18 Aug 2011 09:31:42 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 0CBEF45DE50 for ; Thu, 18 Aug 2011 09:31:42 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id DF28745DE4F for ; Thu, 18 Aug 2011 09:31:41 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id D0F551DB803E for ; Thu, 18 Aug 2011 09:31:41 +0900 (JST) Received: from m107.s.css.fujitsu.com (m107.s.css.fujitsu.com [10.240.81.147]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 8C0FE1DB802F for ; Thu, 18 Aug 2011 09:31:41 +0900 (JST) Date: Thu, 18 Aug 2011 09:24:21 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [patch] memcg: pin execution to current cpu while draining stock Message-Id: <20110818092421.856b74fe.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110817194927.GA10982@redhat.com> References: <2f17df54db6661c39a05669d08a9e6257435b898.1311338634.git.mhocko@suse.cz> <20110725101657.21f85bf0.kamezawa.hiroyu@jp.fujitsu.com> <20110817194927.GA10982@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Michal Hocko , linux-mm@kvack.org, Balbir Singh , Andrew Morton , linux-kernel@vger.kernel.org On Wed, 17 Aug 2011 21:49:27 +0200 Johannes Weiner wrote: > Commit d1a05b6 'memcg: do not try to drain per-cpu caches without > pages' added a drain_local_stock() call to a preemptible section. > > The draining task looks up the cpu-local stock twice to set the > draining-flag, then to drain the stock and clear the flag again. If > the task is migrated to a different CPU in between, noone will clear > the flag on the first stock and it will be forever undrainable. Its > charge can not be recovered and the cgroup can not be deleted anymore. > > Properly pin the task to the executing CPU while draining stocks. > > Signed-off-by: Johannes Weiner > Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Thanks. I think Shaoha Li reported this. Acked-by: KAMEZAWA Hiroyuki ] 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. == Andrew, could you pull this one , too ? http://www.spinics.net/lists/linux-mm/msg22636.html Thanks, -Kame > --- > mm/memcontrol.c | 9 ++------- > 1 files changed, 2 insertions(+), 7 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 697a1d5..e9b1206 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2085,13 +2085,7 @@ 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; > @@ -2108,6 +2102,7 @@ static void drain_all_stock(struct mem_cgroup *root_mem, bool sync) > schedule_work_on(cpu, &stock->work); > } > } > + put_cpu(); > > if (!sync) > goto out; > -- > 1.7.6 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- 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