From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A668C433F5 for ; Wed, 29 Aug 2018 22:25:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D54E20644 for ; Wed, 29 Aug 2018 22:25:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D54E20644 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727251AbeH3CYe (ORCPT ); Wed, 29 Aug 2018 22:24:34 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39814 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727187AbeH3CYe (ORCPT ); Wed, 29 Aug 2018 22:24:34 -0400 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 9EB18BB6; Wed, 29 Aug 2018 22:25:34 +0000 (UTC) Date: Wed, 29 Aug 2018 15:25:33 -0700 From: Andrew Morton To: Larry Chen Cc: mfasheh@suse.com, jlbec@evilplan.org, linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: Re: [PATCH] fix crash on ocfs2_duplicate_clusters_by_page Message-Id: <20180829152533.431fd4972ae046943cabc2e3@linux-foundation.org> In-Reply-To: <20180829074740.9438-1-lchen@suse.com> References: <20180829074740.9438-1-lchen@suse.com> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 29 Aug 2018 15:47:40 +0800 Larry Chen wrote: > ocfs2_duplicate_clusters_by_page may crash if one of extent's pages is dirty. > When a page has not been written back, it is still in dirty state. If > ocfs2_duplicate_clusters_by_page is called against the > dirty page, the crash happens. > > To fix this bug, we can just unlock the page and wait the page until > it's not dirty. > > The following is the buck trace dump: > > kernel BUG at /root/code/ocfs2/refcounttree.c:2961! > [exception RIP: ocfs2_duplicate_clusters_by_page+822] > __ocfs2_move_extent+0x80/0x450 [ocfs2] > ? __ocfs2_claim_clusters+0x130/0x250 [ocfs2] > ocfs2_defrag_extent+0x5b8/0x5e0 [ocfs2] > __ocfs2_move_extents_range+0x2a4/0x470 [ocfs2] > ocfs2_move_extents+0x180/0x3b0 [ocfs2] > ? ocfs2_wait_for_recovery+0x13/0x70 [ocfs2] > ocfs2_ioctl_move_extents+0x133/0x2d0 [ocfs2] > ocfs2_ioctl+0x253/0x640 [ocfs2] > do_vfs_ioctl+0x90/0x5f0 > SyS_ioctl+0x74/0x80 > do_syscall_64+0x74/0x140 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > > --- a/fs/ocfs2/refcounttree.c > +++ b/fs/ocfs2/refcounttree.c > @@ -2946,6 +2946,7 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > if (map_end & (PAGE_SIZE - 1)) > to = map_end & (PAGE_SIZE - 1); > > +retry: > page = find_or_create_page(mapping, page_index, GFP_NOFS); > if (!page) { > ret = -ENOMEM; > @@ -2957,8 +2958,15 @@ int ocfs2_duplicate_clusters_by_page(handle_t *handle, > * In case PAGE_SIZE <= CLUSTER_SIZE, This page > * can't be dirtied before we CoW it out. > */ Looks sane, but the below change shows that the above comment is untrue. Can we please update the comment as well? > - if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) > - BUG_ON(PageDirty(page)); > + if (PAGE_SIZE <= OCFS2_SB(sb)->s_clustersize) { > + if (PageDirty(page)) { > + /* > + * write_on_page will unlock the page on return > + */ > + ret = write_one_page(page); > + goto retry; > + } > + } > > if (!PageUptodate(page)) { > ret = block_read_full_page(page, ocfs2_get_block);