From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f172.google.com (mail-ig0-f172.google.com [209.85.213.172]) by kanga.kvack.org (Postfix) with ESMTP id 214DF6B0055 for ; Fri, 1 Aug 2014 17:42:22 -0400 (EDT) Received: by mail-ig0-f172.google.com with SMTP id h15so2320539igd.5 for ; Fri, 01 Aug 2014 14:42:21 -0700 (PDT) Received: from mail-ie0-x22b.google.com (mail-ie0-x22b.google.com [2607:f8b0:4001:c03::22b]) by mx.google.com with ESMTPS id fu3si25253240icb.49.2014.08.01.14.42.21 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 01 Aug 2014 14:42:21 -0700 (PDT) Received: by mail-ie0-f171.google.com with SMTP id at1so6632277iec.2 for ; Fri, 01 Aug 2014 14:42:21 -0700 (PDT) Date: Fri, 1 Aug 2014 14:42:19 -0700 (PDT) From: David Rientjes Subject: Re: [patch 2/3] mm, oom: remove unnecessary check for NULL zonelist In-Reply-To: <20140801133444.GH9952@cmpxchg.org> Message-ID: References: <20140731152659.GB9952@cmpxchg.org> <20140801133444.GH9952@cmpxchg.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner , Andrew Morton Cc: "Kirill A. Shutemov" , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, 1 Aug 2014, Johannes Weiner wrote: > > > out_of_memory() wants the zonelist that was used during allocation, > > > not just the random first node's zonelist that's simply picked to > > > serialize page fault OOM kills system-wide. > > > > > > This would even change how panic_on_oom behaves for page fault OOMs > > > (in a completely unpredictable way) if we get CONSTRAINED_CPUSET. > > > > > > This change makes no sense to me. > > > > > > > Allocations during fault will be constrained by the cpuset's mems, if we > > are oom then why would we panic when panic_on_oom == 1? > > Can you please address the concerns I raised? > I see one concern: that panic_on_oom == 1 will not trigger on pagefault when constrained by cpusets. To address that, I'll state that, since cpuset-constrained allocations are the allocation context for pagefaults, panic_on_oom == 1 should not trigger on pagefault when constrained by cpusets. > And please describe user-visible changes in the changelog. > Ok, Andrew please annotate the changelog for mm-oom-remove-unnecessary-check-for-null-zonelist.patch by including: This also causes panic_on_oom == 1 to not panic the machine when the pagefault is constrained by the mems of current's cpuset. That behavior agrees with the semantics of the sysctl in Documentation/sysctl/vm.txt. -- 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