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,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 BDDF0C2D0D1 for ; Sun, 29 Dec 2019 18:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 96DA0208C4 for ; Sun, 29 Dec 2019 18:01:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577642507; bh=qGO+dJN8DQLA7z0WHQvmHEjfA8N94jz8uE3u4QqCzRU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FWh8QcJ4SJCE7N+X3DBeLzp62gBa3+/zE8xjhnk2jb249DnC7x7rY+7SwZQPltpIT 0NjvZ2cz330Ynk7X1aucNUiuv3LvmwxpDPPlS5juyj2Wiw0UxT6d9p5AXIAz4WzQAg rCAMHA9pkmuxn3r9XJiC0oZR1nYhKs2TOSeM+fX8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733000AbfL2Rzu (ORCPT ); Sun, 29 Dec 2019 12:55:50 -0500 Received: from mail.kernel.org ([198.145.29.99]:44852 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732995AbfL2Rzt (ORCPT ); Sun, 29 Dec 2019 12:55:49 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 599DC21744; Sun, 29 Dec 2019 17:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577642148; bh=qGO+dJN8DQLA7z0WHQvmHEjfA8N94jz8uE3u4QqCzRU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JXG5wu5m8dlBPPHk/PX2Ngerj2WaCO93HWG77BbTN5kDK2B78ccslFm+imuLYYRoU bKn3+eX/Ij4+lyldY420BlwpBJa2jPXlRCKwUG841aqPRfzSiOhpVa6UmHcI5LUjB1 Wexmj1qHIuvDliKZxBGeJl8VSTdeynd08sCZ+jwo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Thumshirn , Omar Sandoval , David Sterba , Sasha Levin Subject: [PATCH 5.4 361/434] btrfs: dont prematurely free work in reada_start_machine_worker() Date: Sun, 29 Dec 2019 18:26:54 +0100 Message-Id: <20191229172725.951305544@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191229172702.393141737@linuxfoundation.org> References: <20191229172702.393141737@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Omar Sandoval [ Upstream commit e732fe95e4cad35fc1df278c23a32903341b08b3 ] Currently, reada_start_machine_worker() frees the reada_machine_work and then calls __reada_start_machine() to do readahead. This is another potential instance of the bug in "btrfs: don't prematurely free work in run_ordered_work()". There _might_ already be a deadlock here: reada_start_machine_worker() can depend on itself through stacked filesystems (__read_start_machine() -> reada_start_machine_dev() -> reada_tree_block_flagged() -> read_extent_buffer_pages() -> submit_one_bio() -> btree_submit_bio_hook() -> btrfs_map_bio() -> submit_stripe_bio() -> submit_bio() onto a loop device can trigger readahead on the lower filesystem). Either way, let's fix it by freeing the work at the end. Reviewed-by: Johannes Thumshirn Signed-off-by: Omar Sandoval Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/reada.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c index ee6f60547a8d..dd4f9c2b7107 100644 --- a/fs/btrfs/reada.c +++ b/fs/btrfs/reada.c @@ -752,21 +752,19 @@ static int reada_start_machine_dev(struct btrfs_device *dev) static void reada_start_machine_worker(struct btrfs_work *work) { struct reada_machine_work *rmw; - struct btrfs_fs_info *fs_info; int old_ioprio; rmw = container_of(work, struct reada_machine_work, work); - fs_info = rmw->fs_info; - - kfree(rmw); old_ioprio = IOPRIO_PRIO_VALUE(task_nice_ioclass(current), task_nice_ioprio(current)); set_task_ioprio(current, BTRFS_IOPRIO_READA); - __reada_start_machine(fs_info); + __reada_start_machine(rmw->fs_info); set_task_ioprio(current, old_ioprio); - atomic_dec(&fs_info->reada_works_cnt); + atomic_dec(&rmw->fs_info->reada_works_cnt); + + kfree(rmw); } static void __reada_start_machine(struct btrfs_fs_info *fs_info) -- 2.20.1