From: Josef Bacik <josef@toxicpanda.com>
To: linux-btrfs@vger.kernel.org, kernel-team@fb.com
Cc: Qu Wenruo <wqu@suse.com>,
Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: [PATCH v5 03/52] btrfs: fix lockdep splat in btrfs_recover_relocation
Date: Mon, 7 Dec 2020 08:56:55 -0500 [thread overview]
Message-ID: <aeedf174df718917ea2e17eb9fae1b68baf09d96.1607349282.git.josef@toxicpanda.com> (raw)
In-Reply-To: <cover.1607349281.git.josef@toxicpanda.com>
While testing the error paths of relocation I hit the following lockdep
splat
======================================================
WARNING: possible circular locking dependency detected
5.10.0-rc6+ #217 Not tainted
------------------------------------------------------
mount/779 is trying to acquire lock:
ffffa0e676945418 (&fs_info->balance_mutex){+.+.}-{3:3}, at: btrfs_recover_balance+0x2f0/0x340
but task is already holding lock:
ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 (btrfs-root-00){++++}-{3:3}:
down_read_nested+0x43/0x130
__btrfs_tree_read_lock+0x27/0x100
btrfs_read_lock_root_node+0x31/0x40
btrfs_search_slot+0x462/0x8f0
btrfs_update_root+0x55/0x2b0
btrfs_drop_snapshot+0x398/0x750
clean_dirty_subvols+0xdf/0x120
btrfs_recover_relocation+0x534/0x5a0
btrfs_start_pre_rw_mount+0xcb/0x170
open_ctree+0x151f/0x1726
btrfs_mount_root.cold+0x12/0xea
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
vfs_kern_mount.part.0+0x71/0xb0
btrfs_mount+0x10d/0x380
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
path_mount+0x433/0xc10
__x64_sys_mount+0xe3/0x120
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #1 (sb_internal#2){.+.+}-{0:0}:
start_transaction+0x444/0x700
insert_balance_item.isra.0+0x37/0x320
btrfs_balance+0x354/0xf40
btrfs_ioctl_balance+0x2cf/0x380
__x64_sys_ioctl+0x83/0xb0
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
-> #0 (&fs_info->balance_mutex){+.+.}-{3:3}:
__lock_acquire+0x1120/0x1e10
lock_acquire+0x116/0x370
__mutex_lock+0x7e/0x7b0
btrfs_recover_balance+0x2f0/0x340
open_ctree+0x1095/0x1726
btrfs_mount_root.cold+0x12/0xea
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
vfs_kern_mount.part.0+0x71/0xb0
btrfs_mount+0x10d/0x380
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
path_mount+0x433/0xc10
__x64_sys_mount+0xe3/0x120
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
other info that might help us debug this:
Chain exists of:
&fs_info->balance_mutex --> sb_internal#2 --> btrfs-root-00
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(btrfs-root-00);
lock(sb_internal#2);
lock(btrfs-root-00);
lock(&fs_info->balance_mutex);
*** DEADLOCK ***
2 locks held by mount/779:
#0: ffffa0e60dc040e0 (&type->s_umount_key#47/1){+.+.}-{3:3}, at: alloc_super+0xb5/0x380
#1: ffffa0e60ee31da8 (btrfs-root-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x27/0x100
stack backtrace:
CPU: 0 PID: 779 Comm: mount Not tainted 5.10.0-rc6+ #217
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Call Trace:
dump_stack+0x8b/0xb0
check_noncircular+0xcf/0xf0
? trace_call_bpf+0x139/0x260
__lock_acquire+0x1120/0x1e10
lock_acquire+0x116/0x370
? btrfs_recover_balance+0x2f0/0x340
__mutex_lock+0x7e/0x7b0
? btrfs_recover_balance+0x2f0/0x340
? btrfs_recover_balance+0x2f0/0x340
? rcu_read_lock_sched_held+0x3f/0x80
? kmem_cache_alloc_trace+0x2c4/0x2f0
? btrfs_get_64+0x5e/0x100
btrfs_recover_balance+0x2f0/0x340
open_ctree+0x1095/0x1726
btrfs_mount_root.cold+0x12/0xea
? rcu_read_lock_sched_held+0x3f/0x80
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
vfs_kern_mount.part.0+0x71/0xb0
btrfs_mount+0x10d/0x380
? __kmalloc_track_caller+0x2f2/0x320
legacy_get_tree+0x30/0x50
vfs_get_tree+0x28/0xc0
? capable+0x3a/0x60
path_mount+0x433/0xc10
__x64_sys_mount+0xe3/0x120
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This is thankfully straightforward to fix, simply release the path
before we setup the reloc_ctl.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
---
fs/btrfs/volumes.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 7930e1c78c45..49ba941f0314 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4318,6 +4318,8 @@ int btrfs_recover_balance(struct btrfs_fs_info *fs_info)
btrfs_warn(fs_info,
"balance: cannot set exclusive op status, resume manually");
+ btrfs_release_path(path);
+
mutex_lock(&fs_info->balance_mutex);
BUG_ON(fs_info->balance_ctl);
spin_lock(&fs_info->balance_lock);
--
2.26.2
next prev parent reply other threads:[~2020-12-07 13:58 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-07 13:56 [PATCH v5 00/52] Cleanup error handling in relocation Josef Bacik
2020-12-07 13:56 ` [PATCH v5 01/52] btrfs: allow error injection for btrfs_search_slot and btrfs_cow_block Josef Bacik
2020-12-07 13:56 ` [PATCH v5 02/52] btrfs: modify the new_root highest_objectid under a ref count Josef Bacik
2020-12-08 13:51 ` Nikolay Borisov
2020-12-07 13:56 ` Josef Bacik [this message]
2020-12-07 13:56 ` [PATCH v5 04/52] btrfs: keep track of the root owner for relocation reads Josef Bacik
2020-12-07 13:56 ` [PATCH v5 05/52] btrfs: noinline btrfs_should_cancel_balance Josef Bacik
2020-12-07 13:56 ` [PATCH v5 06/52] btrfs: do not cleanup upper nodes in btrfs_backref_cleanup_node Josef Bacik
2020-12-07 13:56 ` [PATCH v5 07/52] btrfs: pass down the tree block level through ref-verify Josef Bacik
2020-12-07 13:57 ` [PATCH v5 08/52] btrfs: make sure owner is set in ref-verify Josef Bacik
2020-12-07 13:57 ` [PATCH v5 09/52] btrfs: don't clear ret in btrfs_start_dirty_block_groups Josef Bacik
2020-12-07 13:57 ` [PATCH v5 10/52] btrfs: convert some BUG_ON()'s to ASSERT()'s in do_relocation Josef Bacik
2020-12-07 13:57 ` [PATCH v5 11/52] btrfs: convert BUG_ON()'s in relocate_tree_block Josef Bacik
2020-12-07 13:57 ` [PATCH v5 12/52] btrfs: return an error from btrfs_record_root_in_trans Josef Bacik
2020-12-07 13:57 ` [PATCH v5 13/52] btrfs: handle errors from select_reloc_root() Josef Bacik
2020-12-08 14:44 ` Zygo Blaxell
2020-12-07 13:57 ` [PATCH v5 14/52] btrfs: convert BUG_ON()'s in select_reloc_root() to proper errors Josef Bacik
2020-12-07 13:57 ` [PATCH v5 15/52] btrfs: check record_root_in_trans related failures in select_reloc_root Josef Bacik
2020-12-07 13:57 ` [PATCH v5 16/52] btrfs: do proper error handling in record_reloc_root_in_trans Josef Bacik
2020-12-07 13:57 ` [PATCH v5 17/52] btrfs: handle btrfs_record_root_in_trans failure in btrfs_rename_exchange Josef Bacik
2020-12-07 13:57 ` [PATCH v5 18/52] btrfs: handle btrfs_record_root_in_trans failure in btrfs_rename Josef Bacik
2020-12-07 13:57 ` [PATCH v5 19/52] btrfs: handle btrfs_record_root_in_trans failure in btrfs_delete_subvolume Josef Bacik
2020-12-07 13:57 ` [PATCH v5 20/52] btrfs: handle btrfs_record_root_in_trans failure in btrfs_recover_log_trees Josef Bacik
2020-12-07 13:57 ` [PATCH v5 21/52] btrfs: handle btrfs_record_root_in_trans failure in create_subvol Josef Bacik
2020-12-07 13:57 ` [PATCH v5 22/52] btrfs: btrfs: handle btrfs_record_root_in_trans failure in relocate_tree_block Josef Bacik
2020-12-07 13:57 ` [PATCH v5 23/52] btrfs: handle btrfs_record_root_in_trans failure in start_transaction Josef Bacik
2020-12-07 13:57 ` [PATCH v5 24/52] btrfs: handle record_root_in_trans failure in qgroup_account_snapshot Josef Bacik
2020-12-07 13:57 ` [PATCH v5 25/52] btrfs: handle record_root_in_trans failure in btrfs_record_root_in_trans Josef Bacik
2020-12-07 13:57 ` [PATCH v5 26/52] btrfs: handle record_root_in_trans failure in create_pending_snapshot Josef Bacik
2020-12-07 13:57 ` [PATCH v5 27/52] btrfs: do not panic in __add_reloc_root Josef Bacik
2020-12-08 13:53 ` Nikolay Borisov
2020-12-07 13:57 ` [PATCH v5 28/52] btrfs: have proper error handling in btrfs_init_reloc_root Josef Bacik
2020-12-07 13:57 ` [PATCH v5 29/52] btrfs: do proper error handling in create_reloc_root Josef Bacik
2020-12-07 13:57 ` [PATCH v5 30/52] btrfs: validate ->reloc_root after recording root in trans Josef Bacik
2020-12-07 13:57 ` [PATCH v5 31/52] btrfs: handle btrfs_update_reloc_root failure in commit_fs_roots Josef Bacik
2020-12-07 13:57 ` [PATCH v5 32/52] btrfs: change insert_dirty_subvol to return errors Josef Bacik
2020-12-07 13:57 ` [PATCH v5 33/52] btrfs: handle btrfs_update_reloc_root failure in insert_dirty_subvol Josef Bacik
2020-12-07 13:57 ` [PATCH v5 34/52] btrfs: handle btrfs_update_reloc_root failure in prepare_to_merge Josef Bacik
2020-12-07 13:57 ` [PATCH v5 35/52] btrfs: do proper error handling in btrfs_update_reloc_root Josef Bacik
2020-12-07 13:57 ` [PATCH v5 36/52] btrfs: convert logic BUG_ON()'s in replace_path to ASSERT()'s Josef Bacik
2020-12-07 13:57 ` [PATCH v5 37/52] btrfs: handle btrfs_cow_block errors in replace_path Josef Bacik
2020-12-07 13:57 ` [PATCH v5 38/52] btrfs: handle btrfs_search_slot failure " Josef Bacik
2020-12-07 13:57 ` [PATCH v5 39/52] btrfs: handle errors in reference count manipulation " Josef Bacik
2020-12-07 13:57 ` [PATCH v5 40/52] btrfs: handle extent reference errors in do_relocation Josef Bacik
2020-12-07 13:57 ` [PATCH v5 41/52] btrfs: check for BTRFS_BLOCK_FLAG_FULL_BACKREF being set improperly Josef Bacik
2020-12-07 13:57 ` [PATCH v5 42/52] btrfs: remove the extent item sanity checks in relocate_block_group Josef Bacik
2020-12-07 13:57 ` [PATCH v5 43/52] btrfs: do proper error handling in create_reloc_inode Josef Bacik
2020-12-07 13:57 ` [PATCH v5 44/52] btrfs: handle __add_reloc_root failures in btrfs_recover_relocation Josef Bacik
2020-12-07 13:57 ` [PATCH v5 45/52] btrfs: cleanup error handling in prepare_to_merge Josef Bacik
2020-12-07 13:57 ` [PATCH v5 46/52] btrfs: handle extent corruption with select_one_root properly Josef Bacik
2020-12-07 13:57 ` [PATCH v5 47/52] btrfs: do proper error handling in merge_reloc_roots Josef Bacik
2020-12-07 13:57 ` [PATCH v5 48/52] btrfs: check return value of btrfs_commit_transaction in relocation Josef Bacik
2020-12-07 13:57 ` [PATCH v5 49/52] btrfs: do not WARN_ON() if we can't find the reloc root Josef Bacik
2020-12-07 13:57 ` [PATCH v5 50/52] btrfs: print the actual offset in btrfs_root_name Josef Bacik
2020-12-07 13:57 ` [PATCH v5 51/52] btrfs: fix reloc root leak with 0 ref reloc roots on recovery Josef Bacik
2020-12-07 13:57 ` [PATCH v5 52/52] btrfs: splice remaining dirty_bg's onto the transaction dirty bg list Josef Bacik
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