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=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 F2C9FC3B187 for ; Mon, 10 Feb 2020 12:35:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CC4AC20873 for ; Mon, 10 Feb 2020 12:35:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338147; bh=gmREiz7bV0/2WCNzoGoXG6xtO6yA6RtRtVd2MC1Pjbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=bB8n9ifCLjJti4FpE92mF5wg+jwUWLKBTIKlr+w/iLUWDX5nGmg+4v84aB/+SgYjT X5/JVsW0Qt7MaRMqmPeWEmJMOV3oE1Ert9maDBkAT9Fc1JwZerlPCDAiWzRPLnecS1 eC4PxYRn3kbKsVp+O/VQqVoOaBUW2KQ+ye7BYclM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728105AbgBJMfq (ORCPT ); Mon, 10 Feb 2020 07:35:46 -0500 Received: from mail.kernel.org ([198.145.29.99]:52620 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727926AbgBJMf1 (ORCPT ); Mon, 10 Feb 2020 07:35:27 -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 9C5F5215A4; Mon, 10 Feb 2020 12:35:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338126; bh=gmREiz7bV0/2WCNzoGoXG6xtO6yA6RtRtVd2MC1Pjbw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QIWLitU0T7JpfDQ051VJfbLwLJgxLA0x/zHg8rpghEfGwyjVxt+bH642QvEPx/EUE 2Dq4uc8STrvbhaXWkuGNfL2b96oOG+9WeHHq88jBkuKAykagXt8WB7DqUwmDEWiAxX X8dBE4LuptlE32XrIDg2aJSbxw6yYK7thTVMaxDE= 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 4.19 067/195] ubifs: Fix deadlock in concurrent bulk-read and writepage Date: Mon, 10 Feb 2020 04:32:05 -0800 Message-Id: <20200210122312.379483037@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122305.731206734@linuxfoundation.org> References: <20200210122305.731206734@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 @@ -798,7 +798,9 @@ 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))