From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f46.google.com (mail-pb0-f46.google.com [209.85.160.46]) by kanga.kvack.org (Postfix) with ESMTP id E8DE46B00BA for ; Tue, 5 Nov 2013 23:45:10 -0500 (EST) Received: by mail-pb0-f46.google.com with SMTP id un15so3462720pbc.5 for ; Tue, 05 Nov 2013 20:45:10 -0800 (PST) Received: from psmtp.com ([74.125.245.140]) by mx.google.com with SMTP id p2si1557885pbe.158.2013.11.05.20.45.08 for ; Tue, 05 Nov 2013 20:45:09 -0800 (PST) Received: by mail-ie0-f169.google.com with SMTP id ar20so17174715iec.28 for ; Tue, 05 Nov 2013 20:45:07 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <1383693987-14171-1-git-send-email-snanda@chromium.org> Date: Tue, 5 Nov 2013 20:45:07 -0800 Message-ID: Subject: Re: [PATCH] mm, oom: Fix race when selecting process to kill From: Luigi Semenzato Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Sameer Nanda , msb@facebook.com Cc: David Rientjes , Andrew Morton , mhocko@suse.cz, Johannes Weiner , Rusty Russell , linux-mm@kvack.org, linux-kernel@vger.kernel.org It's interesting that this was known for 3+ years, but nobody bothered adding a small warning to the code. We noticed this because it's actually happening on Chromebooks in the field. We try to minimize OOM kills, but we can deal with them. Of course, a hung kernel we cannot deal with. On Tue, Nov 5, 2013 at 7:04 PM, Sameer Nanda wrote: > > > > On Tue, Nov 5, 2013 at 5:27 PM, David Rientjes wrote: >> >> On Tue, 5 Nov 2013, Luigi Semenzato wrote: >> >> > It's not enough to hold a reference to the task struct, because it can >> > still be taken out of the circular list of threads. The RCU >> > assumptions don't hold in that case. >> > >> >> Could you please post a proper bug report that isolates this at the cause? > > > We've been running into this issue on Chrome OS. crbug.com/256326 has > additional > details. The issue manifests itself as a soft lockup. > > The kernel we've been seeing this on is 3.8. > > We have a pretty consistent repro currently. Happy to try out other > suggestions > for a fix. > >> >> >> Thanks. > > > > > -- > Sameer -- 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