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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0CD0EC2BA83 for ; Thu, 13 Feb 2020 16:07:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7AAF217F4 for ; Thu, 13 Feb 2020 16:07:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581610034; bh=vF2xtnGldzOfqvnK52m1DzUvSRJ9Qju3vRFkjNDBDf4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UqWVTMSZ0xw3N9LHc/08Qx1XjlDIgmioYJscL3RavX+5Vbj/sxCCy35GcVRMT63W2 XwMtEFAELgMBe1jmX9O0oLL4Znq39O9XYXwAfECyNfdp8lLKQOo9NWe87KvNeivXSA tWcCWJe7b3OZ6SwdJK8LVHsjQ1ek0IIZKaIuRdmw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388330AbgBMQHN (ORCPT ); Thu, 13 Feb 2020 11:07:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:34480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728394AbgBMPX3 (ORCPT ); Thu, 13 Feb 2020 10:23:29 -0500 Received: from localhost (unknown [104.132.1.104]) (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 C0FD0246B3; Thu, 13 Feb 2020 15:23:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581607408; bh=vF2xtnGldzOfqvnK52m1DzUvSRJ9Qju3vRFkjNDBDf4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cWCA77t0FcxC8logfhqFxw6eNZFzevOEjB7HMkrHgvG3z1C8DHztmlSzzVh+96BIQ Xu7VIZrZmjeC6R+jAiZGixYXovjrrA1AFpPjFgLVx1fPGM6YqRRJi0UbURhTFJCA5j e1ndEkhNp/qHnsfAcfMdSlcLZAl0GPE4rDVuvdj4= 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 , Sasha Levin Subject: [PATCH 4.9 029/116] ubifs: Fix deadlock in concurrent bulk-read and writepage Date: Thu, 13 Feb 2020 07:19:33 -0800 Message-Id: <20200213151854.296626030@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200213151842.259660170@linuxfoundation.org> References: <20200213151842.259660170@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 [ Upstream commit f5de5b83303e61b1f3fb09bd77ce3ac2d7a475f2 ] 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: Sasha Levin --- 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 f2e6162f8e656..5ef0d1d607431 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -783,7 +783,9 @@ 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)) -- 2.20.1