From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 3E3406B01EE for ; Mon, 5 Apr 2010 18:49:55 -0400 (EDT) Date: Mon, 5 Apr 2010 15:49:23 -0700 From: Andrew Morton Subject: Re: [patch -mm] memcg: make oom killer a no-op when no killable task can be found Message-Id: <20100405154923.23228529.akpm@linux-foundation.org> In-Reply-To: References: <20100328145528.GA14622@desktop> <20100328162821.GA16765@redhat.com> <20100329140633.GA26464@desktop> <20100330142923.GA10099@desktop> <20100331095714.9137caab.kamezawa.hiroyu@jp.fujitsu.com> <20100331151356.673c16c0.kamezawa.hiroyu@jp.fujitsu.com> <20100331063007.GN3308@balbir.in.ibm.com> <20100405143059.3b56862f.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: KAMEZAWA Hiroyuki , anfei , KOSAKI Motohiro , nishimura@mxp.nes.nec.co.jp, Balbir Singh , linux-mm@kvack.org List-ID: On Mon, 5 Apr 2010 15:40:27 -0700 (PDT) David Rientjes wrote: > On Mon, 5 Apr 2010, Andrew Morton wrote: > > > > > It's pointless to try to kill current if select_bad_process() did not > > > > find an eligible task to kill in mem_cgroup_out_of_memory() since it's > > > > guaranteed that current is a member of the memcg that is oom and it is, > > > > by definition, unkillable. > > > > > > > > Signed-off-by: David Rientjes > > > > --- > > > > mm/oom_kill.c | 5 +---- > > > > 1 files changed, 1 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > > > > --- a/mm/oom_kill.c > > > > +++ b/mm/oom_kill.c > > > > @@ -500,12 +500,9 @@ void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask) > > > > read_lock(&tasklist_lock); > > > > retry: > > > > p = select_bad_process(&points, limit, mem, CONSTRAINT_NONE, NULL); > > > > - if (PTR_ERR(p) == -1UL) > > > > + if (!p || PTR_ERR(p) == -1UL) > > > > goto out; > > > > > > > > - if (!p) > > > > - p = current; > > > > - > > > > if (oom_kill_process(p, gfp_mask, 0, points, limit, mem, > > > > "Memory cgroup out of memory")) > > > > goto retry; > > > > > > > > > > Are there any objections to merging this? It's pretty straight-forward > > > given the fact that oom_kill_process() would fail if select_bad_process() > > > returns NULL even if p is set to current since it was not found to be > > > eligible during the tasklist scan. > > > > I've lost the plot on the oom-killer patches. Half the things I'm > > seeing don't even apply. > > > > This patch applies cleanly on mmotm-2010-03-24-14-48 and I don't see > anything that has been added since then that touches > mem_cgroup_out_of_memory(). I'm working on another mmotm at present. > > Perhaps I should drop the lot and we start again. We still haven't > > resolved the procfs back-compat issue, either. > > I haven't seen any outstanding compatibility issues raised. The only > thing that isn't backwards compatible is consolidating > /proc/sys/vm/oom_kill_allocating_task and /proc/sys/vm/oom_dump_tasks into > /proc/sys/vm/oom_kill_quick. We can do that because we've enabled > oom_dump_tasks by default so that systems that use both of these tunables > need to now disable oom_dump_tasks to avoid the costly tasklist scan. This can break stuff, as I've already described - if a startup tool is correctly checking its syscall return values and a /procfs file vanishes, the app may bail out and not work. Others had other objections, iirc. -- 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