From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f42.google.com (mail-wm0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id 781D66B0038 for ; Mon, 14 Dec 2015 05:57:22 -0500 (EST) Received: by wmnn186 with SMTP id n186so115187683wmn.0 for ; Mon, 14 Dec 2015 02:57:22 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id z76si24588280wmz.87.2015.12.14.02.57.21 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 14 Dec 2015 02:57:21 -0800 (PST) Date: Mon, 14 Dec 2015 11:57:19 +0100 From: Michal Hocko Subject: Re: mm related crash Message-ID: <20151214105719.GA9544@dhcp22.suse.cz> References: <20151210154801.GA12007@lahna.fi.intel.com> <20151214092433.GA90449@black.fi.intel.com> <20151214100556.GB4540@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin Cc: "Kirill A. Shutemov" , Mika Westerberg , Hugh Dickins , "linux-mm@kvack.org" On Mon 14-12-15 13:13:22, Andrey Ryabinin wrote: > 2015-12-14 13:05 GMT+03:00 Michal Hocko : > > On Mon 14-12-15 11:24:33, Kirill A. Shutemov wrote: > >> On Thu, Dec 10, 2015 at 05:48:01PM +0200, Mika Westerberg wrote: > >> > Hi Kirill, > >> > > >> > I got following crash on my desktop machine while building swift. It > >> > reproduces pretty easily on 4.4-rc4. > >> > > >> > Before it happens the ld process is killed by OOM killer. I attached the > >> > whole dmesg. > >> > > >> > [ 254.740603] page:ffffea00111c31c0 count:2 mapcount:0 mapping: (null) index:0x0 > >> > [ 254.740636] flags: 0x5fff8000048028(uptodate|lru|swapcache|swapbacked) > >> > [ 254.740655] page dumped because: VM_BUG_ON_PAGE(!PageLocked(page)) > >> > [ 254.740679] ------------[ cut here ]------------ > >> > [ 254.740690] kernel BUG at mm/memcontrol.c:5270! > >> > >> > >> Hm. I don't see how this can happen. > > > > What a coincidence. I have just posted a similar report: > > http://lkml.kernel.org/r/20151214100156.GA4540@dhcp22.suse.cz except I > > have hit the VM_BUG_ON from a different path. My suspicion is that > > somebody unlocks the page while we are waiting on the writeback. > > I am trying to reproduce this now. > > Guys, this is fixed in rc5 - dfd01f026058a ("sched/wait: Fix the > signal handling fix"). > http://lkml.kernel.org/r/<20151212162342.GF11257@ret.masoncoding.com> Hmm, so you think that some callpath was doing wait_on_page_locked and the above bug would allow a race and then unlock the page under our feet? That would make some sense to me but I haven't checked the code to see which path that would be. I am also not able to reproduce this again... -- 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