From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id B8E4A6B0035 for ; Tue, 7 Jan 2014 19:25:27 -0500 (EST) Received: by mail-pd0-f176.google.com with SMTP id w10so1040915pde.21 for ; Tue, 07 Jan 2014 16:25:27 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id k3si38067961pbb.234.2014.01.07.16.25.05 for ; Tue, 07 Jan 2014 16:25:26 -0800 (PST) Date: Tue, 7 Jan 2014 16:25:03 -0800 From: Andrew Morton Subject: Re: [patch 1/2] mm, memcg: avoid oom notification when current needs access to memory reserves Message-Id: <20140107162503.f751e880410f61a109cdcc2b@linux-foundation.org> In-Reply-To: <20131219144134.GH10855@dhcp22.suse.cz> References: <20131210103827.GB20242@dhcp22.suse.cz> <20131211095549.GA18741@dhcp22.suse.cz> <20131212103159.GB2630@dhcp22.suse.cz> <20131217162342.GG28991@dhcp22.suse.cz> <20131218200434.GA4161@dhcp22.suse.cz> <20131219144134.GH10855@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: David Rientjes , Johannes Weiner , KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, "Eric W. Biederman" On Thu, 19 Dec 2013 15:41:34 +0100 Michal Hocko wrote: > On Wed 18-12-13 22:09:12, David Rientjes wrote: > > On Wed, 18 Dec 2013, Michal Hocko wrote: > > > > > > For memory isolation, we'd only want to bypass memcg charges when > > > > absolutely necessary and it seems like TIF_MEMDIE is the only case where > > > > that's required. We don't give processes with pending SIGKILLs or those > > > > in the exit() path access to memory reserves in the page allocator without > > > > first determining that reclaim can't make any progress for the same reason > > > > and then we only do so by setting TIF_MEMDIE when calling the oom killer. > > > > > > While I do understand arguments about isolation I would also like to be > > > practical here. How many charges are we talking about? Dozen pages? Much > > > more? > > > > The PF_EXITING bypass is indeed much less concerning than the > > fatal_signal_pending() bypass. I just spent a happy half hour reliving this thread and ended up deciding I agreed with everyone! I appears that many more emails are needed so I think I'll drop http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch for now. The claim that mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch will impact existing userspace seems a bit dubious to me. > OK, so can we at least agree on the patch posted here: > https://lkml.org/lkml/2013/12/12/129. This is a real bug and definitely > worth fixing. Yes, can we please get Eric's bug fixed? I don't believe that Eric has tested either https://lkml.org/lkml/2013/12/12/129 or http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-avoid-oom-notification-when-current-needs-access-to-memory-reserves.patch. Is he the only person who can reproduce this? -- 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