From patchwork Mon May 17 14:00:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 440811 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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 D97B7C43460 for ; Mon, 17 May 2021 14:59:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF210613CE for ; Mon, 17 May 2021 14:59:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239255AbhEQPBH (ORCPT ); Mon, 17 May 2021 11:01:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:60874 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241935AbhEQO7C (ORCPT ); Mon, 17 May 2021 10:59:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5711E619BE; Mon, 17 May 2021 14:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621261580; bh=T8ng7qXIxMGsKLp+IokrAv4sxsh+PsghkPdJTspU24M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BMOe+h5nxWbzvq2ja6GGKz9pBIIbuPhxICVkdBE9V4fvT1A7z1zDNZ/PAB8/YPmj2 pendu7hUCApmHeJIlFTDuOfoK47ClWGKWThElLSqwTg63nHJ6DwSVT9RK9A+YjNaX1 LdEZePemMoDpuPlkOMYF6Jlthr3/10erKPKn3464= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yi Zhuang , Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 5.11 131/329] f2fs: Fix a hungtask problem in atomic write Date: Mon, 17 May 2021 16:00:42 +0200 Message-Id: <20210517140306.551076948@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140302.043055203@linuxfoundation.org> References: <20210517140302.043055203@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yi Zhuang [ Upstream commit be1ee45d51384161681ecf21085a42d316ae25f7 ] In the cache writing process, if it is an atomic file, increase the page count of F2FS_WB_CP_DATA, otherwise increase the page count of F2FS_WB_DATA. When you step into the hook branch due to insufficient memory in f2fs_write_begin, f2fs_drop_inmem_pages_all will be called to traverse all atomic inodes and clear the FI_ATOMIC_FILE mark of all atomic files. In f2fs_drop_inmem_pages，first acquire the inmem_lock , revoke all the inmem_pages, and then clear the FI_ATOMIC_FILE mark. Before this mark is cleared, other threads may hold inmem_lock to add inmem_pages to the inode that has just been emptied inmem_pages, and increase the page count of F2FS_WB_CP_DATA. When the IO returns, it is found that the FI_ATOMIC_FILE flag is cleared by f2fs_drop_inmem_pages_all, and f2fs_is_atomic_file returns false,which causes the page count of F2FS_WB_DATA to be decremented. The page count of F2FS_WB_CP_DATA cannot be cleared. Finally, hungtask is triggered in f2fs_wait_on_all_pages because get_pages will never return zero. process A: process B: f2fs_drop_inmem_pages_all ->f2fs_drop_inmem_pages of inode#1 ->mutex_lock(&fi->inmem_lock) ->__revoke_inmem_pages of inode#1 f2fs_ioc_commit_atomic_write ->mutex_unlock(&fi->inmem_lock) ->f2fs_commit_inmem_pages of inode#1 ->mutex_lock(&fi->inmem_lock) ->__f2fs_commit_inmem_pages ->f2fs_do_write_data_page ->f2fs_outplace_write_data ->do_write_page ->f2fs_submit_page_write ->inc_page_count(sbi, F2FS_WB_CP_DATA ) ->mutex_unlock(&fi->inmem_lock) ->spin_lock(&sbi->inode_lock[ATOMIC_FILE]); ->clear_inode_flag(inode, FI_ATOMIC_FILE) ->spin_unlock(&sbi->inode_lock[ATOMIC_FILE]) f2fs_write_end_io ->dec_page_count(sbi, F2FS_WB_DATA ); We can fix the problem by putting the action of clearing the FI_ATOMIC_FILE mark into the inmem_lock lock. This operation can ensure that no one will submit the inmem pages before the FI_ATOMIC_FILE mark is cleared, so that there will be no atomic writes waiting for writeback. Fixes: 57864ae5ce3a ("f2fs: limit # of inmemory pages") Signed-off-by: Yi Zhuang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/segment.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 73db79d958bd..af765d60351f 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -327,23 +327,27 @@ void f2fs_drop_inmem_pages(struct inode *inode) struct f2fs_sb_info *sbi = F2FS_I_SB(inode); struct f2fs_inode_info *fi = F2FS_I(inode); - while (!list_empty(&fi->inmem_pages)) { + do { mutex_lock(&fi->inmem_lock); + if (list_empty(&fi->inmem_pages)) { + fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; + + spin_lock(&sbi->inode_lock[ATOMIC_FILE]); + if (!list_empty(&fi->inmem_ilist)) + list_del_init(&fi->inmem_ilist); + if (f2fs_is_atomic_file(inode)) { + clear_inode_flag(inode, FI_ATOMIC_FILE); + sbi->atomic_files--; + } + spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); + + mutex_unlock(&fi->inmem_lock); + break; + } __revoke_inmem_pages(inode, &fi->inmem_pages, true, false, true); mutex_unlock(&fi->inmem_lock); - } - - fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0; - - spin_lock(&sbi->inode_lock[ATOMIC_FILE]); - if (!list_empty(&fi->inmem_ilist)) - list_del_init(&fi->inmem_ilist); - if (f2fs_is_atomic_file(inode)) { - clear_inode_flag(inode, FI_ATOMIC_FILE); - sbi->atomic_files--; - } - spin_unlock(&sbi->inode_lock[ATOMIC_FILE]); + } while (1); } void f2fs_drop_inmem_page(struct inode *inode, struct page *page)