From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH next/mmotm] ext4: fix cache_es after merge_left Date: Thu, 27 Sep 2012 16:39:20 -0400 Message-ID: <20120927203920.GB9585@thunk.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Zheng Liu , Yongqiang Yang , Allison Henderson , Lukas Czerner , Andrew Morton , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: Hugh Dickins Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:52761 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754815Ab2I0Uj1 (ORCPT ); Thu, 27 Sep 2012 16:39:27 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: 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)? Thanks!! - Ted