From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f179.google.com (mail-wi0-f179.google.com [209.85.212.179]) by kanga.kvack.org (Postfix) with ESMTP id CD6716B006C for ; Thu, 26 Mar 2015 12:07:46 -0400 (EDT) Received: by wibg7 with SMTP id g7so154257366wib.1 for ; Thu, 26 Mar 2015 09:07:46 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id r6si10660577wjx.75.2015.03.26.09.07.44 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 26 Mar 2015 09:07:44 -0700 (PDT) Date: Thu, 26 Mar 2015 17:07:42 +0100 From: Michal Hocko Subject: Re: [patch 06/12] mm: oom_kill: simplify OOM killer locking Message-ID: <20150326160742.GR15257@dhcp22.suse.cz> References: <1427264236-17249-1-git-send-email-hannes@cmpxchg.org> <1427264236-17249-7-git-send-email-hannes@cmpxchg.org> <20150326133111.GJ15257@dhcp22.suse.cz> <20150326151746.GC23973@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150326151746.GC23973@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Tetsuo Handa , Huang Ying , Andrea Arcangeli , Dave Chinner , Theodore Ts'o On Thu 26-03-15 11:17:46, Johannes Weiner wrote: > On Thu, Mar 26, 2015 at 02:31:11PM +0100, Michal Hocko wrote: [...] > > > @@ -795,27 +728,21 @@ bool out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, > > > */ > > > void pagefault_out_of_memory(void) > > > { > > > - struct zonelist *zonelist; > > > - > > > - down_read(&oom_sem); > > > if (mem_cgroup_oom_synchronize(true)) > > > - goto unlock; > > > + return; > > > > OK, so we are back to what David has asked previously. We do not need > > the lock for memcg and oom_killer_disabled because we know that no tasks > > (except for potential oom victim) are lurking around at the time > > oom_killer_disable() is called. So I guess we want to stick a comment > > into mem_cgroup_oom_synchronize before we check for oom_killer_disabled. > > I would prefer everybody that sets TIF_MEMDIE and kills a task to hold > the lock, including memcg. Simplicity is one thing, but also a global > OOM kill might not even be necessary when it's racing with the memcg. sure I am find with that. > > After those are fixed, feel free to add > > Acked-by: Michal Hocko > > Thanks. -- 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