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 0339CC4321E for ; Wed, 6 Apr 2022 00:22:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1587414AbiDFAJG (ORCPT ); Tue, 5 Apr 2022 20:09:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356659AbiDEKYq (ORCPT ); Tue, 5 Apr 2022 06:24:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE1E0BF000; Tue, 5 Apr 2022 03:08:43 -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 7F91AB81C88; Tue, 5 Apr 2022 10:08:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB1CCC385A1; Tue, 5 Apr 2022 10:08:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649153321; bh=+62UOCrEQHJW3+mqmQw8Gx2IGV/ruOwHv2oXrxxSxqQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ai0cHxiJVVQXvDIZGjLr+UnU0Z8TF5JY70YTlk7AqqcQ6J0YjWFFsQ/7kagW3hvlV IMymiqKHys97HgYkuktz9j630+SBNGX9wn+najUTvH1qcpH4aoCGen7M5BIId43a5c BSSJFB4/gXUN9zQwWyIb38Q0BRuSuVc4/9apuO04= 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 5.10 181/599] f2fs: fix to avoid potential deadlock Date: Tue, 5 Apr 2022 09:27:55 +0200 Message-Id: <20220405070304.227278821@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070258.802373272@linuxfoundation.org> References: <20220405070258.802373272@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: linux-kernel@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 1b11a42847c4..d27a92a54447 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -3264,8 +3264,12 @@ 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 7e625806bd4a..5fa10d0b0068 100644 --- a/fs/f2fs/node.c +++ b/fs/f2fs/node.c @@ -2055,8 +2055,12 @@ 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