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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 4D471C433F4 for ; Thu, 30 Aug 2018 03:07:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC6A320644 for ; Thu, 30 Aug 2018 03:07:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EC6A320644 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com 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 S1727360AbeH3HHN (ORCPT ); Thu, 30 Aug 2018 03:07:13 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:47089 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727233AbeH3HHN (ORCPT ); Thu, 30 Aug 2018 03:07:13 -0400 Received: from Beta.suse.asia (prv-ext-foundry1int.gns.novell.com [137.65.251.240]) by smtp2.provo.novell.com with ESMTP (NOT encrypted); Wed, 29 Aug 2018 21:07:08 -0600 From: Larry Chen To: mark@fasheh.com, jlbec@evilplan.org Cc: linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, akpm@linux-foundation.org Subject: [PATCH v4] fix crash on ocfs2_duplicate_clusters_by_page Date: Thu, 30 Aug 2018 11:06:54 +0800 Message-Id: <20180830030654.20872-1-lchen@suse.com> X-Mailer: git-send-email 2.13.7 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 write back the page rather than just wait. The following is the back trace dump: kernel BUG at /root/code/ocfs2/refcounttree.c:2961! BUG_ON(PageDirty(page)); [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 Change-log: 1. Once we find the page is dirty, we do not wait until it's clean, but rather we use write_one_page to write it back 2. write_one_page arguments list changed, adjust and retest this patch. 3. Comments has been changed Signed-off-by: Larry Chen --- fs/ocfs2/refcounttree.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c index 7869622af22a..ed84d05c7d00 100644 --- 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; @@ -2954,11 +2955,18 @@ 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. + * In case PAGE_SIZE <= CLUSTER_SIZE, we do not expect a dirty page, + * so write it back. */ - 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); -- 2.13.7