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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 C1156C352A3 for ; Mon, 10 Feb 2020 13:05:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 982B32070A for ; Mon, 10 Feb 2020 13:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581339926; bh=/glp9sSdbLe3epTTSCqFRgpTWpPljAzDuqmKyRFBIH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QR47qhVB6gR9VQVMmWbCh/rSbjXIowgShJeehyzU2hxbAXqoAKUEbtJk+sOQi64V9 YLx+6M/ADXeDXqET6yugaZir2cZSncMQQziofATDJxkup5mxaJsWU1fcUig92dZ1Hi pH8NGFeSZtanHlcBqF9d/RnQk600VXi74Utey9P0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730814AbgBJNF0 (ORCPT ); Mon, 10 Feb 2020 08:05:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:38940 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729184AbgBJMkE (ORCPT ); Mon, 10 Feb 2020 07:40:04 -0500 Received: from localhost (unknown [209.37.97.194]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F0B712051A; Mon, 10 Feb 2020 12:40:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338404; bh=/glp9sSdbLe3epTTSCqFRgpTWpPljAzDuqmKyRFBIH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y6PSWcRj1D8daXsFeMyWhngvonIn6754Qc0NCAiCTe5mZQwFmE/kZYwkyYvzw/QeP ggdDEIrMkoaQG5ac/8BSw3VyuT8fhgpWbEe0KTOFdsJnuls+CEyuEoimyLwj32MX1k kEnpIt1k3/nhfU9iBb3n88u4nDXdZYeBrV7No9GM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhihao Cheng , "zhangyi (F)" , Stable@vger.kernel.org, Richard Weinberger Subject: [PATCH 5.5 105/367] ubifs: Fix deadlock in concurrent bulk-read and writepage Date: Mon, 10 Feb 2020 04:30:18 -0800 Message-Id: <20200210122434.083181923@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122423.695146547@linuxfoundation.org> References: <20200210122423.695146547@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhihao Cheng commit f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2 upstream. In ubifs, concurrent execution of writepage and bulk read on the same file may cause ABBA deadlock, for example (Reproduce method see Link): Process A(Bulk-read starts from page4) Process B(write page4 back) vfs_read wb_workfn or fsync ... ... generic_file_buffered_read write_cache_pages ubifs_readpage LOCK(page4) ubifs_bulk_read ubifs_writepage LOCK(ui->ui_mutex) ubifs_write_inode ubifs_do_bulk_read LOCK(ui->ui_mutex) find_or_create_page(alloc page4) ↑ LOCK(page4) <-- ABBA deadlock occurs! In order to ensure the serialization execution of bulk read, we can't remove the big lock 'ui->ui_mutex' in ubifs_bulk_read(). Instead, we allow ubifs_do_bulk_read() to lock page failed by replacing find_or_create_page(FGP_LOCK) with pagecache_get_page(FGP_LOCK | FGP_NOWAIT). Signed-off-by: Zhihao Cheng Suggested-by: zhangyi (F) Cc: Fixes: 4793e7c5e1c ("UBIFS: add bulk-read facility") Link: https://bugzilla.kernel.org/show_bug.cgi?id=206153 Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman --- fs/ubifs/file.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -786,7 +786,9 @@ static int ubifs_do_bulk_read(struct ubi if (page_offset > end_index) break; - page = find_or_create_page(mapping, page_offset, ra_gfp_mask); + page = pagecache_get_page(mapping, page_offset, + FGP_LOCK|FGP_ACCESSED|FGP_CREAT|FGP_NOWAIT, + ra_gfp_mask); if (!page) break; if (!PageUptodate(page))