From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zheng Liu Subject: Re: [PATCH next/mmotm] ext4: fix cache_es after merge_left Date: Fri, 28 Sep 2012 06:53:57 +0800 Message-ID: <20120927225357.GA19675@gmail.com> References: <20120927203920.GB9585@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: Theodore Ts'o , Hugh Dickins , Zheng Liu , Yongqiang Yang , Allison Henderson , Lukas Czerner , Andrew Morton , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Return-path: Content-Disposition: inline In-Reply-To: <20120927203920.GB9585@thunk.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, Sep 27, 2012 at 04:39:20PM -0400, Theodore Ts'o wrote: > On Thu, Sep 27, 2012 at 01:31:28PM -0700, Hugh Dickins wrote: > > Kernel build with CONFIG_DEBUG_SLAB or CONFIG_SLUB_DEBUG slub_debug=FPZ > > gives me kernel BUG at fs/ext4/extents_status.c:142! That's the > > BUG_ON(es->start + es->len < es->start) in extent_status_end() called > > from ext4_es_insert_extent(). tree->cache_es has been freed and poisoned. > > > > This comes from when ext4_es_try_to_merge_left() merges es into leftward > > es1, but ext4_es_insert_extent()'s out then updates cache_es to the freed > > extent_status. ext4_es_try_to_merge_right() does not pose a problem. > > > > Change ext4_es_try_to_merge_left() to return whichever extent_status > > should be recorded in tree->cache_es. Remove cache_es update from > > both of them, leaving that to ext4_es_insert_extent()'s out label. > > > > Signed-off-by: Hugh Dickins > > Hugh, thanks for finding this bug! > > Zheng, you were going to send me an updated patch series; can you take > care of merging this patch into your patch series (and crediting Hugh > with a Signed-off-by as appropriate)? Yeah, thanks for fixing it, although I have fixed this problem in my new patch set. I will add a Signed-off-by into the patch. Regards, Zheng