Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932186Ab1ELOFG (ORCPT ); Thu, 12 May 2011 10:05:06 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:46503 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932110Ab1ELOE7 (ORCPT ); Thu, 12 May 2011 10:04:59 -0400 Subject: Re: [PATCH 0/3] Reduce impact to overall system of SLUB using high-order allocations From: James Bottomley To: Pekka Enberg Cc: David Rientjes , Mel Gorman , Andrew Morton , Colin King , Raghavendra D Prabhu , Jan Kara , Chris Mason , Christoph Lameter , Rik van Riel , Johannes Weiner , linux-fsdevel , linux-mm , linux-kernel , linux-ext4 In-Reply-To: <4DCBC0E8.5020609@cs.helsinki.fi> References: <1305127773-10570-1-git-send-email-mgorman@suse.de> <1305149960.2606.53.camel@mulgrave.site> <1305153267.2606.57.camel@mulgrave.site> <4DCBC0E8.5020609@cs.helsinki.fi> Content-Type: text/plain; charset="UTF-8" Date: Thu, 12 May 2011 09:04:56 -0500 Message-ID: <1305209096.2575.14.camel@mulgrave.site> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1600 Lines: 36 On Thu, 2011-05-12 at 14:13 +0300, Pekka Enberg wrote: > On 5/12/11 1:34 AM, James Bottomley wrote: > > On Wed, 2011-05-11 at 15:28 -0700, David Rientjes wrote: > >> On Wed, 11 May 2011, James Bottomley wrote: > >> > >>> OK, I confirm that I can't seem to break this one. No hangs visible, > >>> even when loading up the system with firefox, evolution, the usual > >>> massive untar, X and even a distribution upgrade. > >>> > >>> You can add my tested-by > >>> > >> Your system still hangs with patches 1 and 2 only? > > Yes, but only once in all the testing. With patches 1 and 2 the hang is > > much harder to reproduce, but it still seems to be present if I hit it > > hard enough. > > Patches 1-2 look reasonable to me. I'm not completely convinced of patch > 3, though. Why are we seeing these problems now? This has been in > mainline for a long time already. Shouldn't we fix kswapd? So I'm open to this. The hang occurs when kswapd races around in shrink_slab and never exits. It looks like there's a massive number of wakeups triggering this, but we haven't been able to diagnose it further. turning on PREEMPT gets rid of the hang, so I could try to reproduce with PREEMPT and turn on tracing. The problem so far has been that the number of events is so huge that the trace buffer only captures a few microseconds of output. James -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/