Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753067Ab0GGBrv (ORCPT ); Tue, 6 Jul 2010 21:47:51 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:59497 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835Ab0GGBru (ORCPT ); Tue, 6 Jul 2010 21:47:50 -0400 Date: Tue, 6 Jul 2010 21:47:34 -0400 From: Christoph Hellwig To: Ingo Molnar Cc: Linus Torvalds , Bill Davidsen , Jens Axboe , Christoph Hellwig , Peter Zijlstra , Andrew Morton , Linux Kernel Mailing List , Thomas Gleixner , "Rafael J. Wysocki" Subject: Re: [regression] Crash in wb_clear_pending() Message-ID: <20100707014734.GA2950@infradead.org> References: <20100705085550.GA26775@elte.hu> <20100705164022.GA26995@infradead.org> <20100705171125.GB26202@elte.hu> <20100705171420.GA29697@elte.hu> <20100705182003.GA12332@infradead.org> <4C323177.3070606@kernel.dk> <4C324C78.5090805@tmr.com> <20100706064733.GA12382@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100706064733.GA12382@elte.hu> User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 858 Lines: 20 On Tue, Jul 06, 2010 at 08:47:33AM +0200, Ingo Molnar wrote: > Yeah, i agree - especially since the smaller patch is still pretty large (not > a oneliner), plus it does not appear that the precise failure mode is fully > understood either. The two failure modes we saw are very precicely understood: - access to ->state after it's been freed - access to ->state after the caller which has the bdi_work struct on stack has been woken up. But I seriously fear that there are even more dragons hidden in this maze of bit wakeups and rcu, so replacing it with a proper completion seems by far safer to me. -- 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/