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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6730C4321E for ; Tue, 5 Apr 2022 08:03:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233268AbiDEIFk (ORCPT ); Tue, 5 Apr 2022 04:05:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233967AbiDEH5y (ORCPT ); Tue, 5 Apr 2022 03:57:54 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 387B593990; Tue, 5 Apr 2022 00:51:43 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 260A6B81B14; Tue, 5 Apr 2022 07:51:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80E7DC340EE; Tue, 5 Apr 2022 07:51:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649145093; bh=DAqiT5fbEGmGnuHSi20a1pRvj1HdznkOlj3MSEFwgEo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=06Pdlx8vE7sj5ri+qw9GAEVReN22YZZBnxc3P1zC7diIPoGR17K2b2YiVWhpRvgjG Qr8yTWfytHN6xi/eL/99FnbrMq2RHoUm39oipDCcilEHGluL9ITk0zlib4joYAjyZE fRgdCyJORyOhb/9Ui7CWVZrrm1V4ejMw7xq16B6g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhiguo Niu , Jing Xia , Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.17 0282/1126] f2fs: fix to avoid potential deadlock Date: Tue, 5 Apr 2022 09:17:09 +0200 Message-Id: <20220405070415.887878964@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Chao Yu [ Upstream commit 344150999b7fc88502a65bbb147a47503eca2033 ] Quoted from Jing Xia's report, there is a potential deadlock may happen between kworker and checkpoint as below: [T:writeback] [T:checkpoint] - wb_writeback - blk_start_plug bio contains NodeA was plugged in writeback threads - do_writepages -- sync write inodeB, inc wb_sync_req[DATA] - f2fs_write_data_pages - f2fs_write_single_data_page -- write last dirty page - f2fs_do_write_data_page - set_page_writeback -- clear page dirty flag and PAGECACHE_TAG_DIRTY tag in radix tree - f2fs_outplace_write_data - f2fs_update_data_blkaddr - f2fs_wait_on_page_writeback -- wait NodeA to writeback here - inode_dec_dirty_pages - writeback_sb_inodes - writeback_single_inode - do_writepages - f2fs_write_data_pages -- skip writepages due to wb_sync_req[DATA] - wbc->pages_skipped += get_dirty_pages() -- PAGECACHE_TAG_DIRTY is not set but get_dirty_pages() returns one - requeue_inode -- requeue inode to wb->b_dirty queue due to non-zero.pages_skipped - blk_finish_plug Let's try to avoid deadlock condition by forcing unplugging previous bio via blk_finish_plug(current->plug) once we'v skipped writeback in writepages() due to valid sbi->wb_sync_req[DATA/NODE]. Fixes: 687de7f1010c ("f2fs: avoid IO split due to mixed WB_SYNC_ALL and WB_SYNC_NONE") Signed-off-by: Zhiguo Niu Signed-off-by: Jing Xia Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/data.c | 6 +++++- fs/f2fs/node.c | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 8c417864c66a..e1ef925be60c 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -3163,8 +3163,12 @@ static int __f2fs_write_data_pages(struct address_space *mapping, /* to avoid spliting IOs due to mixed WB_SYNC_ALL and WB_SYNC_NONE */ if (wbc->sync_mode == WB_SYNC_ALL) atomic_inc(&sbi->wb_sync_req[DATA]); - else if (atomic_read(&sbi->wb_sync_req[DATA])) + else if (atomic_read(&sbi->wb_sync_req[DATA])) { + /* to avoid potential deadlock */ + if (current->plug) + blk_finish_plug(current->plug); goto skip_write; + } if (__should_serialize_io(inode, wbc)) { mutex_lock(&sbi->writepages); diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index 50b2874e758c..4ff7dfb54250 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -2111,8 +2111,12 @@ static int f2fs_write_node_pages(struct address_space *mapping, if (wbc->sync_mode == WB_SYNC_ALL) atomic_inc(&sbi->wb_sync_req[NODE]); - else if (atomic_read(&sbi->wb_sync_req[NODE])) + else if (atomic_read(&sbi->wb_sync_req[NODE])) { + /* to avoid potential deadlock */ + if (current->plug) + blk_finish_plug(current->plug); goto skip_write; + } trace_f2fs_writepages(mapping->host, wbc, NODE); -- 2.34.1