From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758812AbYJIM0S (ORCPT ); Thu, 9 Oct 2008 08:26:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756947AbYJIM0H (ORCPT ); Thu, 9 Oct 2008 08:26:07 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:34887 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756780AbYJIM0G (ORCPT ); Thu, 9 Oct 2008 08:26:06 -0400 Date: Thu, 9 Oct 2008 14:25:49 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Peter Zijlstra , Linux Kernel Mailing List Subject: Re: [PATCH] xen: use spin_lock_nest_lock when pinning a pagetable Message-ID: <20081009122549.GA2952@elte.hu> References: <48ED11A3.3090605@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48ED11A3.3090605@goop.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00,DNS_FROM_SECURITYSAGE autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] 0.0 DNS_FROM_SECURITYSAGE RBL: Envelope sender in blackholes.securitysage.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jeremy Fitzhardinge wrote: > When pinning/unpinning a pagetable with split pte locks, we can end up > holding multiple pte locks at once (we need to hold the locks while > there's a pending batched hypercall affecting the pte page). Because > all the pte locks are in the same lock class, lockdep thinks that > we're potentially taking a lock recursively. > > This warning is spurious because we always take the pte locks while > holding mm->page_table_lock. lockdep now has spin_lock_nest_lock to > express this kind of dominant lock use, so use it here so that lockdep > knows what's going on. > > Signed-off-by: Jeremy Fitzhardinge > --- > arch/x86/xen/mmu.c | 74 +++++++++++++++++++++++++++++++++------------------- > arch/x86/xen/mmu.h | 3 -- > 2 files changed, 48 insertions(+), 29 deletions(-) applied to tip/x86/xen, thanks Jeremy! Ingo