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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 4F9B0C83017 for ; Sat, 28 Nov 2020 22:17:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 203CA221FF for ; Sat, 28 Nov 2020 22:17:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388847AbgK1Vtq (ORCPT ); Sat, 28 Nov 2020 16:49:46 -0500 Received: from forward3-smtp.messagingengine.com ([66.111.4.237]:55287 "EHLO forward3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729863AbgK1SBw (ORCPT ); Sat, 28 Nov 2020 13:01:52 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.nyi.internal (Postfix) with ESMTP id 386151944708; Sat, 28 Nov 2020 07:27:18 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Sat, 28 Nov 2020 07:27:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=SCrbHU mbhIgODdOc9VzhikzM13opE+LIcIqeVciqVWw=; b=k3ylqhm1J8jknQQxwpSstX NKhNF4ExLos6eZh901ldwpG+S2xCTi9dJsaRYYkDWnKHtOStVwTH6HQcb/CotgXQ Ukgt8e3vSmxjZ8ac5B6KRKqFyVy3BazgYJbzN8U4XlS8JUEjGJqXJnqmYq7VPiUz qyFu3uYp5PdtLeqSONQTVVDGNQ0VoEF3XwLizrEtvkXUEYpnixmYcJdxhuQV2z2c qhUL6TER7PnLYITRe/J/yCa7GjUco0wu28apUydvxIF/d7gL7V1pQtl6Jem3biL9 SSr1F0i0/Fd3jTq22GJV8qYg7RRcZemlxL/cxoR1jpoiabN7hs0pHkKD1G1TOzeA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedrudehiedggeduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepfeetteehueetheekueevhfefveejheegtdeiudehue ekheeijeefgfeuhfeigefhnecuffhomhgrihhnpehqvghmuhdrohhrghenucfkphepkeef rdekiedrjeegrdeigeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrih hlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id CC1783064AA7; Sat, 28 Nov 2020 07:27:17 -0500 (EST) Subject: FAILED: patch "[PATCH] btrfs: fix lockdep splat when reading qgroup config on mount" failed to apply to 4.4-stable tree To: fdmanana@suse.com, dsterba@suse.com Cc: From: Date: Sat, 28 Nov 2020 13:28:26 +0100 Message-ID: <16065665063666@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 3d05cad3c357a2b749912914356072b38435edfa Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 23 Nov 2020 14:28:44 +0000 Subject: [PATCH] btrfs: fix lockdep splat when reading qgroup config on mount Lockdep reported the following splat when running test btrfs/190 from fstests: [ 9482.126098] ====================================================== [ 9482.126184] WARNING: possible circular locking dependency detected [ 9482.126281] 5.10.0-rc4-btrfs-next-73 #1 Not tainted [ 9482.126365] ------------------------------------------------------ [ 9482.126456] mount/24187 is trying to acquire lock: [ 9482.126534] ffffa0c869a7dac0 (&fs_info->qgroup_rescan_lock){+.+.}-{3:3}, at: qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.126647] but task is already holding lock: [ 9482.126777] ffffa0c892ebd3a0 (btrfs-quota-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x120 [btrfs] [ 9482.126886] which lock already depends on the new lock. [ 9482.127078] the existing dependency chain (in reverse order) is: [ 9482.127213] -> #1 (btrfs-quota-00){++++}-{3:3}: [ 9482.127366] lock_acquire+0xd8/0x490 [ 9482.127436] down_read_nested+0x45/0x220 [ 9482.127528] __btrfs_tree_read_lock+0x27/0x120 [btrfs] [ 9482.127613] btrfs_read_lock_root_node+0x41/0x130 [btrfs] [ 9482.127702] btrfs_search_slot+0x514/0xc30 [btrfs] [ 9482.127788] update_qgroup_status_item+0x72/0x140 [btrfs] [ 9482.127877] btrfs_qgroup_rescan_worker+0xde/0x680 [btrfs] [ 9482.127964] btrfs_work_helper+0xf1/0x600 [btrfs] [ 9482.128039] process_one_work+0x24e/0x5e0 [ 9482.128110] worker_thread+0x50/0x3b0 [ 9482.128181] kthread+0x153/0x170 [ 9482.128256] ret_from_fork+0x22/0x30 [ 9482.128327] -> #0 (&fs_info->qgroup_rescan_lock){+.+.}-{3:3}: [ 9482.128464] check_prev_add+0x91/0xc60 [ 9482.128551] __lock_acquire+0x1740/0x3110 [ 9482.128623] lock_acquire+0xd8/0x490 [ 9482.130029] __mutex_lock+0xa3/0xb30 [ 9482.130590] qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.131577] btrfs_read_qgroup_config+0x43a/0x550 [btrfs] [ 9482.132175] open_ctree+0x1228/0x18a0 [btrfs] [ 9482.132756] btrfs_mount_root.cold+0x13/0xed [btrfs] [ 9482.133325] legacy_get_tree+0x30/0x60 [ 9482.133866] vfs_get_tree+0x28/0xe0 [ 9482.134392] fc_mount+0xe/0x40 [ 9482.134908] vfs_kern_mount.part.0+0x71/0x90 [ 9482.135428] btrfs_mount+0x13b/0x3e0 [btrfs] [ 9482.135942] legacy_get_tree+0x30/0x60 [ 9482.136444] vfs_get_tree+0x28/0xe0 [ 9482.136949] path_mount+0x2d7/0xa70 [ 9482.137438] do_mount+0x75/0x90 [ 9482.137923] __x64_sys_mount+0x8e/0xd0 [ 9482.138400] do_syscall_64+0x33/0x80 [ 9482.138873] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 9482.139346] other info that might help us debug this: [ 9482.140735] Possible unsafe locking scenario: [ 9482.141594] CPU0 CPU1 [ 9482.142011] ---- ---- [ 9482.142411] lock(btrfs-quota-00); [ 9482.142806] lock(&fs_info->qgroup_rescan_lock); [ 9482.143216] lock(btrfs-quota-00); [ 9482.143629] lock(&fs_info->qgroup_rescan_lock); [ 9482.144056] *** DEADLOCK *** [ 9482.145242] 2 locks held by mount/24187: [ 9482.145637] #0: ffffa0c8411c40e8 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0xb9/0x400 [ 9482.146061] #1: ffffa0c892ebd3a0 (btrfs-quota-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x120 [btrfs] [ 9482.146509] stack backtrace: [ 9482.147350] CPU: 1 PID: 24187 Comm: mount Not tainted 5.10.0-rc4-btrfs-next-73 #1 [ 9482.147788] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 9482.148709] Call Trace: [ 9482.149169] dump_stack+0x8d/0xb5 [ 9482.149628] check_noncircular+0xff/0x110 [ 9482.150090] check_prev_add+0x91/0xc60 [ 9482.150561] ? kvm_clock_read+0x14/0x30 [ 9482.151017] ? kvm_sched_clock_read+0x5/0x10 [ 9482.151470] __lock_acquire+0x1740/0x3110 [ 9482.151941] ? __btrfs_tree_read_lock+0x27/0x120 [btrfs] [ 9482.152402] lock_acquire+0xd8/0x490 [ 9482.152887] ? qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.153354] __mutex_lock+0xa3/0xb30 [ 9482.153826] ? qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.154301] ? qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.154768] ? qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.155226] qgroup_rescan_init+0x43/0xf0 [btrfs] [ 9482.155690] btrfs_read_qgroup_config+0x43a/0x550 [btrfs] [ 9482.156160] open_ctree+0x1228/0x18a0 [btrfs] [ 9482.156643] btrfs_mount_root.cold+0x13/0xed [btrfs] [ 9482.157108] ? rcu_read_lock_sched_held+0x5d/0x90 [ 9482.157567] ? kfree+0x31f/0x3e0 [ 9482.158030] legacy_get_tree+0x30/0x60 [ 9482.158489] vfs_get_tree+0x28/0xe0 [ 9482.158947] fc_mount+0xe/0x40 [ 9482.159403] vfs_kern_mount.part.0+0x71/0x90 [ 9482.159875] btrfs_mount+0x13b/0x3e0 [btrfs] [ 9482.160335] ? rcu_read_lock_sched_held+0x5d/0x90 [ 9482.160805] ? kfree+0x31f/0x3e0 [ 9482.161260] ? legacy_get_tree+0x30/0x60 [ 9482.161714] legacy_get_tree+0x30/0x60 [ 9482.162166] vfs_get_tree+0x28/0xe0 [ 9482.162616] path_mount+0x2d7/0xa70 [ 9482.163070] do_mount+0x75/0x90 [ 9482.163525] __x64_sys_mount+0x8e/0xd0 [ 9482.163986] do_syscall_64+0x33/0x80 [ 9482.164437] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 9482.164902] RIP: 0033:0x7f51e907caaa This happens because at btrfs_read_qgroup_config() we can call qgroup_rescan_init() while holding a read lock on a quota btree leaf, acquired by the previous call to btrfs_search_slot_for_read(), and qgroup_rescan_init() acquires the mutex qgroup_rescan_lock. A qgroup rescan worker does the opposite: it acquires the mutex qgroup_rescan_lock, at btrfs_qgroup_rescan_worker(), and then tries to update the qgroup status item in the quota btree through the call to update_qgroup_status_item(). This inversion of locking order between the qgroup_rescan_lock mutex and quota btree locks causes the splat. Fix this simply by releasing and freeing the path before calling qgroup_rescan_init() at btrfs_read_qgroup_config(). CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 4621b8043021..a3f0d209fce5 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -497,13 +497,13 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info) break; } out: + btrfs_free_path(path); fs_info->qgroup_flags |= flags; if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON)) clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags); else if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN && ret >= 0) ret = qgroup_rescan_init(fs_info, rescan_progress, 0); - btrfs_free_path(path); if (ret < 0) { ulist_free(fs_info->qgroup_ulist);