From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762834AbZCTK3x (ORCPT ); Fri, 20 Mar 2009 06:29:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762553AbZCTK0z (ORCPT ); Fri, 20 Mar 2009 06:26:55 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:36348 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762546AbZCTK0y (ORCPT ); Fri, 20 Mar 2009 06:26:54 -0400 Subject: [PATCH] lockdep: fix deadlock in lockdep_trace_alloc From: Peter Zijlstra To: Heiko Carstens Cc: Ingo Molnar , Nick Piggin , "lkml," In-Reply-To: <1237544000.24626.52.camel@twins> References: <1237544000.24626.52.camel@twins> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Fri, 20 Mar 2009 11:26:38 +0100 Message-Id: <1237544798.24626.54.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Heiko pointed out that checking for irqs_disabled() after we disable them is quite pointless.. New patch below. --- Subject: lockdep: fix deadlock in lockdep_trace_alloc From: Peter Zijlstra Date: Fri Mar 20 11:24:21 CET 2009 Heiko reported that we grab the graph lock with irqs enabled. Fix this by providing the same wrapper as all other lockdep entry functions have. Reported-by: Heiko Carstens Signed-off-by: Peter Zijlstra --- kernel/lockdep.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) Index: linux-2.6/kernel/lockdep.c =================================================================== --- linux-2.6.orig/kernel/lockdep.c +++ linux-2.6/kernel/lockdep.c @@ -2258,7 +2258,7 @@ void trace_softirqs_off(unsigned long ip debug_atomic_inc(&redundant_softirqs_off); } -void lockdep_trace_alloc(gfp_t gfp_mask) +static void __lockdep_trace_alloc(gfp_t gfp_mask) { struct task_struct *curr = current; @@ -2277,10 +2277,27 @@ void lockdep_trace_alloc(gfp_t gfp_mask) if (!(gfp_mask & __GFP_FS)) return; + mark_held_locks(curr, RECLAIM_FS); +} + +static void check_flags(unsigned long flags); + +void lockdep_trace_alloc(gfp_t gfp_mask) +{ + unsigned long flags; + + if (unlikely(current->lockdep_recursion)) + return; + if (DEBUG_LOCKS_WARN_ON(irqs_disabled())) return; - mark_held_locks(curr, RECLAIM_FS); + raw_local_irq_save(flags); + check_flags(flags); + current->lockdep_recursion = 1; + __lockdep_trace_alloc(gfp_mask); + current->lockdep_recursion = 0; + raw_local_irq_restore(flags); } static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)