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57be052c28
commit fcc99734d1d4ced30167eb02e17f656735cb9928 upstream. [BUG] One run of btrfs/063 triggered the following lockdep warning: ============================================ WARNING: possible recursive locking detected 5.6.0-rc7-custom+ #48 Not tainted -------------------------------------------- kworker/u24:0/7 is trying to acquire lock: ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs] but task is already holding lock: ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs] other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(sb_internal#2); lock(sb_internal#2); *** DEADLOCK *** May be due to missing lock nesting notation 4 locks held by kworker/u24:0/7: #0: ffff88817b495948 ((wq_completion)btrfs-endio-write){+.+.}, at: process_one_work+0x557/0xb80 #1: ffff888189ea7db8 ((work_completion)(&work->normal_work)){+.+.}, at: process_one_work+0x557/0xb80 #2: ffff88817d3a46e0 (sb_internal#2){.+.+}, at: start_transaction+0x66c/0x890 [btrfs] #3: ffff888174ca4da8 (&fs_info->reloc_mutex){+.+.}, at: btrfs_record_root_in_trans+0x83/0xd0 [btrfs] stack backtrace: CPU: 0 PID: 7 Comm: kworker/u24:0 Not tainted 5.6.0-rc7-custom+ #48 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: btrfs-endio-write btrfs_work_helper [btrfs] Call Trace: dump_stack+0xc2/0x11a __lock_acquire.cold+0xce/0x214 lock_acquire+0xe6/0x210 __sb_start_write+0x14e/0x290 start_transaction+0x66c/0x890 [btrfs] btrfs_join_transaction+0x1d/0x20 [btrfs] find_free_extent+0x1504/0x1a50 [btrfs] btrfs_reserve_extent+0xd5/0x1f0 [btrfs] btrfs_alloc_tree_block+0x1ac/0x570 [btrfs] btrfs_copy_root+0x213/0x580 [btrfs] create_reloc_root+0x3bd/0x470 [btrfs] btrfs_init_reloc_root+0x2d2/0x310 [btrfs] record_root_in_trans+0x191/0x1d0 [btrfs] btrfs_record_root_in_trans+0x90/0xd0 [btrfs] start_transaction+0x16e/0x890 [btrfs] btrfs_join_transaction+0x1d/0x20 [btrfs] btrfs_finish_ordered_io+0x55d/0xcd0 [btrfs] finish_ordered_fn+0x15/0x20 [btrfs] btrfs_work_helper+0x116/0x9a0 [btrfs] process_one_work+0x632/0xb80 worker_thread+0x80/0x690 kthread+0x1a3/0x1f0 ret_from_fork+0x27/0x50 It's pretty hard to reproduce, only one hit so far. [CAUSE] This is because we're calling btrfs_join_transaction() without re-using the current running one: btrfs_finish_ordered_io() |- btrfs_join_transaction() <<< Call #1 |- btrfs_record_root_in_trans() |- btrfs_reserve_extent() |- btrfs_join_transaction() <<< Call #2 Normally such btrfs_join_transaction() call should re-use the existing one, without trying to re-start a transaction. But the problem is, in btrfs_join_transaction() call #1, we call btrfs_record_root_in_trans() before initializing current::journal_info. And in btrfs_join_transaction() call #2, we're relying on current::journal_info to avoid such deadlock. [FIX] Call btrfs_record_root_in_trans() after we have initialized current::journal_info. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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.. | ||
tests | ||
acl.c | ||
async-thread.c | ||
async-thread.h | ||
backref.c | ||
backref.h | ||
btrfs_inode.h | ||
check-integrity.c | ||
check-integrity.h | ||
compression.c | ||
compression.h | ||
ctree.c | ||
ctree.h | ||
dedupe.h | ||
delayed-inode.c | ||
delayed-inode.h | ||
delayed-ref.c | ||
delayed-ref.h | ||
dev-replace.c | ||
dev-replace.h | ||
dir-item.c | ||
disk-io.c | ||
disk-io.h | ||
export.c | ||
export.h | ||
extent_io.c | ||
extent_io.h | ||
extent_map.c | ||
extent_map.h | ||
extent-tree.c | ||
file-item.c | ||
file.c | ||
free-space-cache.c | ||
free-space-cache.h | ||
free-space-tree.c | ||
free-space-tree.h | ||
inode-item.c | ||
inode-map.c | ||
inode-map.h | ||
inode.c | ||
ioctl.c | ||
Kconfig | ||
locking.c | ||
locking.h | ||
lzo.c | ||
Makefile | ||
math.h | ||
ordered-data.c | ||
ordered-data.h | ||
orphan.c | ||
print-tree.c | ||
print-tree.h | ||
props.c | ||
props.h | ||
qgroup.c | ||
qgroup.h | ||
raid56.c | ||
raid56.h | ||
rcu-string.h | ||
reada.c | ||
ref-verify.c | ||
ref-verify.h | ||
relocation.c | ||
root-tree.c | ||
scrub.c | ||
send.c | ||
send.h | ||
struct-funcs.c | ||
super.c | ||
sysfs.c | ||
sysfs.h | ||
transaction.c | ||
transaction.h | ||
tree-checker.c | ||
tree-checker.h | ||
tree-defrag.c | ||
tree-log.c | ||
tree-log.h | ||
ulist.c | ||
ulist.h | ||
uuid-tree.c | ||
volumes.c | ||
volumes.h | ||
xattr.c | ||
xattr.h | ||
zlib.c | ||
zstd.c |