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 lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B9264C433EF for ; Sat, 29 Jan 2022 00:37:16 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.94.2) (envelope-from ) id 1nDbjx-0004o8-Fq; Sat, 29 Jan 2022 00:37:16 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1nDbjw-0004o0-6C for linux-f2fs-devel@lists.sourceforge.net; Sat, 29 Jan 2022 00:37:14 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=DFblRwXXYjKA4J7nt9NGCBxiiZ4BsJAb4M9XzvDHqbY=; b=ImUYxJsdMtMoex2y6Mx1hOfs7j f72jdVbTAYSBbNSxlTVOZ6mZu2iC2+2grn0aZs3rRMRZ5S9d3qySrBQPHMqQutbM9BSf7WYha9K+g mx1vvHimuA7C93Zz2dUnn6X1XCVpwZoKvvQEhz7d2wg19TIQrjKxK+Dz4oMyUY3+raPk=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=DFblRwXXYjKA4J7nt9NGCBxiiZ4BsJAb4M9XzvDHqbY=; b=bKKXUlyqmezfBBM7pGPCo2YQDT MC5VUhA9eqdNybshlNatAr9RY3CHHWm1VdKuoMTHFFdAHGvDJhFjMeWd26QDR6gfz3k9NvOHWbumB m9X2wVVfWv+KFk1od7nY4ujpYA7RzmbidmBQh6RlCemdFywHXhfhw3xWdmNI0qY5yx2c=; Received: from dfw.source.kernel.org ([139.178.84.217]) by sfi-mx-2.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.94.2) id 1nDbjt-0006Aw-Rn for linux-f2fs-devel@lists.sourceforge.net; Sat, 29 Jan 2022 00:37:14 +0000 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 dfw.source.kernel.org (Postfix) with ESMTPS id 7B17360BAD; Sat, 29 Jan 2022 00:37:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDFBFC340E7; Sat, 29 Jan 2022 00:37:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1643416627; bh=ouiW9oGv6HXtWJIQRDQ98A6hortJtyz/aXTnLA/yjuM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=pKKn21LmTef1+meSgnLxRAzGVJE/j1YKS9Y2dSpRubtjxTRb7/4pwt/lCvTsx6ErQ wbCW8Qc2RF0ITgt7flUqqqQEmjxAqthzRSnzhvuYNpYeB8QfWjnpBEpKxtC6rdB36m GKeS2w/qimQJJobuAmwz5EC7f/uahexPGRaUSpv72Xkj9I9/EpYiiqTnAnlClCgj+h E20CInzh/K62mSKSlCwa5+17x8/sF/fAyx/sSNltxvwMU7FDW16jov7S1c/Q3kLI5G XQ+BwWnlqB6t4YpuloIvNRYrpOPckYCE1Rxzy3iJSf7wKadLtxgwRbpaaw3+qMfjIF qjnBBlsUfE+mQ== Date: Fri, 28 Jan 2022 16:37:06 -0800 From: Jaegeuk Kim To: Chao Yu Message-ID: References: <20220127054449.24711-1-chao@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Headers-End: 1nDbjt-0006Aw-Rn Subject: Re: [f2fs-dev] [PATCH] f2fs: fix to avoid potential deadlock X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jing Xia , Zhiguo Niu , linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On 01/28, Chao Yu wrote: > On 2022/1/28 5:59, Jaegeuk Kim wrote: > > On 01/27, Chao Yu wrote: > > > 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 > > > > I'm still trying to understand more precisely. So, how is it possible to > > have bio having node write in this current context? > > IMO, after above blk_start_plug(), it may plug some inode's node page in kworker > during writebacking node_inode's data page (which should be node page)? Wasn't that added into a different task->plug? > > Thanks, > > > > > > - 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 > > > --- > > > 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 76d6fe7b0c8f..932a4c81acaf 100644 > > > --- a/fs/f2fs/data.c > > > +++ b/fs/f2fs/data.c > > > @@ -3174,8 +3174,12 @@ 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 556fcd8457f3..69c6bcaf5aae 100644 > > > --- a/fs/f2fs/node.c > > > +++ b/fs/f2fs/node.c > > > @@ -2106,8 +2106,12 @@ 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); > > > -- > > > 2.32.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel