From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933391Ab2AJBoi (ORCPT ); Mon, 9 Jan 2012 20:44:38 -0500 Received: from rcsinet15.oracle.com ([148.87.113.117]:29739 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932283Ab2AJBog (ORCPT ); Mon, 9 Jan 2012 20:44:36 -0500 Date: Mon, 9 Jan 2012 20:44:32 -0500 From: Chris Mason To: Dave Jones Cc: Linux Kernel Subject: Re: btrfs/mmap lockdep report from 3.2 Message-ID: <20120110014432.GC26546@shiny> Mail-Followup-To: Chris Mason , Dave Jones , Linux Kernel References: <20120110010331.GA15942@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120110010331.GA15942@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet22.oracle.com [141.146.126.238] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090207.4F0B9803.0016,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 09, 2012 at 08:03:32PM -0500, Dave Jones wrote: > Just hit this with Linus' tree as of 37cfc3f67db9f2d907f6bfcfae590cdbbef623e8 > > Dave > > [ 130.932837] ====================================================== > [ 130.933032] [ INFO: possible circular locking dependency detected ] > [ 130.933032] 3.2.0+ #19 Not tainted > [ 130.933032] ------------------------------------------------------- > [ 130.933032] firefox/1630 is trying to acquire lock: > [ 130.933032] (&sb->s_type->i_mutex_key#13){+.+.+.}, at: [] btrfs_page_mkwrite+0x5b/0x310 [btrfs] > [ 130.933032] > [ 130.933032] but task is already holding lock: > [ 130.933032] (&mm->mmap_sem){++++++}, at: [] do_page_fault+0xe8/0x5d0 > [ 130.933032] > [ 130.933032] which lock already depends on the new lock. >>From a lockdep point of view, this is real. But the page_mkwrite code is never called on directories so it is actually safe. We'll fix it up. -chris