From: Ted Ts'o Subject: Re: [PATCH] fix oops in ext4_mb_release_group_pa tracing Date: Sat, 9 Oct 2010 18:26:28 -0400 Message-ID: <20101009222628.GB11237@thunk.org> References: <4C6D7116.2080905@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development , Josef Bacik To: Eric Sandeen Return-path: Received: from thunk.org ([69.25.196.29]:51795 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753212Ab0JIW02 (ORCPT ); Sat, 9 Oct 2010 18:26:28 -0400 Content-Disposition: inline In-Reply-To: <4C6D7116.2080905@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Aug 19, 2010 at 12:59:50PM -0500, Eric Sandeen wrote: > Our QA reported an oops in the ext4_mb_release_group_pa tracing, > and Josef Bacik pointed out that it was because we may have a > non-null but uninitialized ac_inode in the allocation context. > > I can reproduce it when running xfstests with ext4 tracepoints on, > on a CONFIG_SLAB_DEBUG kernel. > > We call trace_ext4_mb_release_group_pa from 2 places, > ext4_mb_discard_group_preallocations and > ext4_mb_discard_lg_preallocations > > In both cases we allocate an ac as a container just for tracing (!) > and never fill in the ac_inode. There's no reason to be assigning, > testing, or printing it as far as I can see, so just remove it from > the tracepoint. > > Signed-off-by: Eric Sandeen Thanks for the ping; I've added it to the ext4 patch tree. - Ted