Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758891Ab1BPJ6v (ORCPT ); Wed, 16 Feb 2011 04:58:51 -0500 Received: from casper.infradead.org ([85.118.1.10]:39837 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755219Ab1BPJ6t convert rfc822-to-8bit (ORCPT ); Wed, 16 Feb 2011 04:58:49 -0500 Subject: Re: [PATCH] fix pgd_lock deadlock From: Peter Zijlstra To: Andrea Arcangeli Cc: Thomas Gleixner , Jeremy Fitzhardinge , "H. Peter Anvin" , the arch/x86 maintainers , "Xen-devel@lists.xensource.com" , Linux Kernel Mailing List , Ian Campbell , Jan Beulich , Larry Woodman , Andrew Morton , Andi Kleen , Johannes Weiner , Hugh Dickins , Rik van Riel In-Reply-To: <20110215231733.GR5935@random.random> References: <20110204012109.GP5843@random.random> <4D4C6F45.6010204@goop.org> <20110207232045.GJ3347@random.random> <20110215190710.GL5935@random.random> <20110215195450.GO5935@random.random> <20110215225234.GP5935@random.random> <20110215231733.GR5935@random.random> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 16 Feb 2011 10:58:14 +0100 Message-ID: <1297850294.2413.30.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 953 Lines: 22 On Wed, 2011-02-16 at 00:17 +0100, Andrea Arcangeli wrote: > On Wed, Feb 16, 2011 at 12:03:30AM +0100, Thomas Gleixner wrote: > > I assume you run it with a lockdep enabled kernel as well, right ? > > Yes, I always run with lockdep and prove locking enabled on my test > box, not sure how it's meant to trigger more bugs in this case, the > debug check that should be relevant for this is DEBUG_VM and that is > enabled too of course. I didn't try DEBUG_PAGEALLOC yet. I think what Thomas tried to tell you is that your VM_BUG_ON(in_interrupt()) is fully redundant if you have lockdep enabled. Lockdep will warn you if a !irqsave lock is taken from IRQ context, since that is a clear inversion problem. -- 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/