From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 469A16B00B6 for ; Fri, 20 Nov 2009 05:52:16 -0500 (EST) Subject: Re: lockdep complaints in slab allocator From: Peter Zijlstra In-Reply-To: <84144f020911200238w3d3ecb38k92ca595beee31de5@mail.gmail.com> References: <20091118181202.GA12180@linux.vnet.ibm.com> <84144f020911192249l6c7fa495t1a05294c8f5b6ac8@mail.gmail.com> <1258709153.11284.429.camel@laptop> <84144f020911200238w3d3ecb38k92ca595beee31de5@mail.gmail.com> Content-Type: text/plain; charset="UTF-8" Date: Fri, 20 Nov 2009 11:52:08 +0100 Message-ID: <1258714328.11284.522.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Pekka Enberg Cc: paulmck@linux.vnet.ibm.com, linux-mm@kvack.org, cl@linux-foundation.org, mpm@selenic.com, LKML , Nick Piggin List-ID: On Fri, 2009-11-20 at 12:38 +0200, Pekka Enberg wrote: > > > On Fri, Nov 20, 2009 at 11:25 AM, Peter Zijlstra wrote: > > 2) propagate the nesting information and user spin_lock_nested(), given > > that slab is already a rat's nest, this won't make it any less obvious. > > spin_lock_nested() doesn't really help us here because there's a > _real_ possibility of a recursive spin lock here, right? Well, I was working under the assumption that your analysis of it being a false positive was right ;-) I briefly tried to verify that, but got lost and gave up, at which point I started looking for ways to annotate. If you're now saying its a real deadlock waiting to happen, then the quick fix is to always do the call_rcu() thing, or a slightly longer fix might be to take that slab object and propagate it out up the callchain and free it once we drop the nc->lock for the current __cache_free() or something. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org