From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760622AbXJEJbs (ORCPT ); Fri, 5 Oct 2007 05:31:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754095AbXJEJbk (ORCPT ); Fri, 5 Oct 2007 05:31:40 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:56347 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754047AbXJEJbk (ORCPT ); Fri, 5 Oct 2007 05:31:40 -0400 Subject: [PATCH] lockdep: fix mismatched lockdep_depth/curr_chain_hash From: Peter Zijlstra To: Gregory Haskins , stable Cc: mingo@elte.hu, linux-kernel In-Reply-To: <20071005034058.20275.21559.stgit@ghaskins-t60p.haskins.net> References: <20071005034058.20275.21559.stgit@ghaskins-t60p.haskins.net> Content-Type: text/plain Date: Fri, 05 Oct 2007 11:31:26 +0200 Message-Id: <1191576686.22357.64.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Stable team, please consider this patch for the next 22-stable. --- Subject: lockdep: fix mismatched lockdep_depth/curr_chain_hash From: Gregory Haskins It is possible for the current->curr_chain_key to become inconsistent with the current index if the chain fails to validate. The end result is that future lock_acquire() operations may inadvertently fail to find a hit in the cache resulting in a new node being added to the graph for every acquire. [ peterz: this might explain some of the lockdep is so _slow_ complaints. ] [ mingo: this does not impact the correctness of validation, but may slow down future operations significantly, if the chain gets very long. ] Signed-off-by: Gregory Haskins Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/lockdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/kernel/lockdep.c =================================================================== --- linux-2.6.orig/kernel/lockdep.c +++ linux-2.6/kernel/lockdep.c @@ -2166,7 +2166,6 @@ out_calc_hash: } #endif chain_key = iterate_chain_key(chain_key, id); - curr->curr_chain_key = chain_key; /* * Trylock needs to maintain the stack of held locks, but it @@ -2215,6 +2214,7 @@ out_calc_hash: if (unlikely(!debug_locks)) return 0; + curr->curr_chain_key = chain_key; curr->lockdep_depth++; check_chain_key(curr); #ifdef CONFIG_DEBUG_LOCKDEP