From: Dmitry Monakhov Subject: Re: NULL pointer dereference in ext4_ext_remove_space on 3.5.1 Date: Mon, 17 Sep 2012 16:21:44 +0400 Message-ID: <87fw6get5z.fsf@openvz.org> References: <20120816024654.GB3781@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Kernel hackers , ext4 hackers , maze@google.com To: Theodore Ts'o , Marti Raudsepp Return-path: Received: from mail-lb0-f174.google.com ([209.85.217.174]:45533 "EHLO mail-lb0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755969Ab2IQMVs (ORCPT ); Mon, 17 Sep 2012 08:21:48 -0400 In-Reply-To: <20120816024654.GB3781@thunk.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, 15 Aug 2012 22:46:54 -0400, Theodore Ts'o wrote: > On Wed, Aug 15, 2012 at 09:33:29PM +0300, Marti Raudsepp wrote: > > I was moving and deleting some files between two of my ext4 partitions > > when it suddenly crashed and dropped me into an kernel oops screen > > (below). I'm using ext4 on kernel 3.5.1 (Arch Linux). Ohh, I've missed that gigantic topic, but still i've found the bug. patch is available here http://patchwork.ozlabs.org/patch/183649/ > > > BUG: unable to handle kernel NULL pointer dereference at 000...00028 > > IP: [...] ext4_ext_remove_space+0xaa4/0xef0 [ext4] > > Someone else has reported a similar crash, but we don't yet have > enough information to narrow it down quite yet. > > If you could try applying the following debugging patch, and then try > to reproduce the failure, it would be really helpful. > > Thanks!! > > - Ted > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index 769151d..3394d52 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -2432,6 +2432,10 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode, > > /* the header must be checked already in ext4_ext_remove_space() */ > ext_debug("truncate since %u in leaf to %u\n", start, end); > + if (!path[depth].p_hdr && !path[depth].p_bh) { > + EXT4_ERROR_INODE(inode, "depth %d", depth); > + BUG_ON(1); > + } > if (!path[depth].p_hdr) > path[depth].p_hdr = ext_block_hdr(path[depth].p_bh); > eh = path[depth].p_hdr; > @@ -2730,6 +2734,10 @@ cont: > /* this is index block */ > if (!path[i].p_hdr) { > ext_debug("initialize header\n"); > + if (!path[i].p_hdr && !path[i].p_bh) { > + EXT4_ERROR_INODE(inode, "i=%d", i); > + BUG_ON(1); > + } > path[i].p_hdr = ext_block_hdr(path[i].p_bh); > } > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html