From patchwork Mon Feb 10 12:30:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 231718 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 3870FC352A3 for ; Mon, 10 Feb 2020 13:22:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEC2920715 for ; Mon, 10 Feb 2020 13:22:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581340971; bh=/glp9sSdbLe3epTTSCqFRgpTWpPljAzDuqmKyRFBIH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xOGKn4OXXSPqkanM+vYNb5gyw6JYRvL1q0g9CbPWiWn0N+aAVL+Wx17WMakzSQ4mP RDn4zruo4pbtWi565Z0t9xeKqLvkBEpaJwcH2yveOj0RGe+FZgHDgv0jzgXzTMGKZK PdiKd668HQ5dMKBU/1cQUQky/Cet4fNqhCjztNzo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728193AbgBJNWm (ORCPT ); Mon, 10 Feb 2020 08:22:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:58822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728268AbgBJMhV (ORCPT ); Mon, 10 Feb 2020 07:37:21 -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 099552085B; Mon, 10 Feb 2020 12:37:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581338241; bh=/glp9sSdbLe3epTTSCqFRgpTWpPljAzDuqmKyRFBIH0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=spguriA9Qi8ndVFTFtsuJRZt9DI35i/bA+MwqwiSQX6wpIwwdn3cBe/p3CHBhjVD2 UJm/sEoxQz0T8VvSBwQ27TWHTT2GTAbLq19uXB1kF/1/IorCDAQqACUq07Hs+RhzpO 9+4rLIDGXuPIUZpK+1DRJTNO/AJqwDxEHTtdt34o= 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 5.4 095/309] ubifs: Fix deadlock in concurrent bulk-read and writepage Date: Mon, 10 Feb 2020 04:30:51 -0800 Message-Id: <20200210122415.250833630@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200210122406.106356946@linuxfoundation.org> References: <20200210122406.106356946@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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))