From patchwork Sat Jan 11 09:50:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Zhihao Cheng X-Patchwork-Id: 1221575 X-Patchwork-Delegate: richard@nod.at Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20170209 header.b=THw5PAC7; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 47vw0n04Qyz9sNx for ; Sat, 11 Jan 2020 20:44:03 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=skXi8wSg7lUP9nOpf6sI3Olq0W75OdjSkdoxSD/QR3A=; b=THw5PAC7W3HqIj NjcP0r2F1vnTtaTqAdwYnLG5nt7ngnRvEej8zThMY74StivzviQk+UfCzJCkgi7xgdun2iSIShgMr y8eRd82NyEm1Nht18dbmjmLAEhW157+uZkqgLyEG7tNpOzXTOqdXIp2JHAPNC89z5NRMckAkW5r0X w+p3EV4ljsF9O6KXJiWKB3R9+iD/Gux+Wc20sYlCKFU6j7K9nKW+q7LNYS4twMxPJa8WRJtCkJdD6 qvVctgrutv8PmAIxrhHM9Azx+TLRk8ekdVbPZfyqmRZqrmCwUbsWqorTIEbTNbRM3yXrUUe4i+dHq zpI6pPD81gZGW1w6BkFQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iqDIx-0005pj-Q2; Sat, 11 Jan 2020 09:43:39 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1iqDIu-0005oy-44 for linux-mtd@lists.infradead.org; Sat, 11 Jan 2020 09:43:38 +0000 Received: from DGGEMS410-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id E12A9E2B3071DDC9B529; Sat, 11 Jan 2020 17:43:30 +0800 (CST) Received: from huawei.com (10.90.53.225) by DGGEMS410-HUB.china.huawei.com (10.3.19.210) with Microsoft SMTP Server id 14.3.439.0; Sat, 11 Jan 2020 17:43:20 +0800 From: Zhihao Cheng To: , , Subject: [PATCH v2] ubifs: Fix deadlock in concurrent bulk-read and writepage Date: Sat, 11 Jan 2020 17:50:36 +0800 Message-ID: <1578736236-141308-1-git-send-email-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.90.53.225] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200111_014336_332884_CE5D67C2 X-CRM114-Status: UNSURE ( 7.02 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [45.249.212.191 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Sender: "linux-mtd" Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org 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 --- fs/ubifs/file.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index cd52585..c649048 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -786,7 +786,9 @@ static int ubifs_do_bulk_read(struct ubifs_info *c, struct bu_info *bu, 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))