From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932618Ab1JCVH0 (ORCPT ); Mon, 3 Oct 2011 17:07:26 -0400 Received: from casper.infradead.org ([85.118.1.10]:57464 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752190Ab1JCVHW convert rfc822-to-8bit (ORCPT ); Mon, 3 Oct 2011 17:07:22 -0400 Subject: Re: lockdep recursive locking detected (rcu_kthread / __cache_free) From: Peter Zijlstra To: Christoph Lameter Cc: "Paul E. McKenney" , Sitsofe Wheeler , Ingo Molnar , linux-kernel@vger.kernel.org, penberg@kernel.org, mpm@selenic.com, linux-mm@kvack.org Date: Mon, 03 Oct 2011 23:06:19 +0200 In-Reply-To: References: <20111003175322.GA26122@sucs.org> <20111003203139.GH2403@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.0.3- Message-ID: <1317675980.9417.1.camel@twins> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-10-03 at 15:46 -0500, Christoph Lameter wrote: > On Mon, 3 Oct 2011, Paul E. McKenney wrote: > > > The first lock was acquired here in an RCU callback. The later lock that > > lockdep complained about appears to have been acquired from a recursive > > call to __cache_free(), with no help from RCU. This looks to me like > > one of the issues that arise from the slab allocator using itself to > > allocate slab metadata. > > Right. However, this is a false positive since the slab cache with > the metadata is different from the slab caches with the slab data. The slab > cache with the metadata does not use itself any metadata slab caches. Sure, but we're supposed to have annotated that.. see init_node_lock_keys()