From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 025E16B007B for ; Mon, 23 Nov 2009 14:50:26 -0500 (EST) Subject: Re: lockdep complaints in slab allocator From: Pekka Enberg In-Reply-To: References: <20091118181202.GA12180@linux.vnet.ibm.com> <84144f020911192249l6c7fa495t1a05294c8f5b6ac8@mail.gmail.com> <1258709153.11284.429.camel@laptop> <84144f020911200238w3d3ecb38k92ca595beee31de5@mail.gmail.com> <1258714328.11284.522.camel@laptop> <4B067816.6070304@cs.helsinki.fi> <1258729748.4104.223.camel@laptop> <1259002800.5630.1.camel@penberg-laptop> Date: Mon, 23 Nov 2009 21:50:14 +0200 Message-Id: <1259005814.15619.14.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Peter Zijlstra , paulmck@linux.vnet.ibm.com, linux-mm@kvack.org, mpm@selenic.com, LKML , Nick Piggin List-ID: On Mon, 23 Nov 2009, Pekka Enberg wrote: > > That turns out to be _very_ hard. How about something like the following > > untested patch which delays slab_destroy() while we're under nc->lock. On Mon, 2009-11-23 at 13:30 -0600, Christoph Lameter wrote: > Code changes to deal with a diagnostic issue? OK, fair enough. If I suffer permanent brain damage from staring at the SLAB code for too long, I hope you and Matt will chip in to pay for my medication. I think I was looking at the wrong thing here. The problem is in cache_free_alien() so the comment in slab_destroy() isn't relevant. Looking at init_lock_keys() we already do special lockdep annotations but there's a catch (as explained in a comment on top of on_slab_alc_key): * We set lock class for alien array caches which are up during init. * The lock annotation will be lost if all cpus of a node goes down and * then comes back up during hotplug Paul said he was running CPU hotplug so maybe that explains the problem? Pekka -- 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