Re: [syzbot] [ocfs2?] WARNING in ocfs2_unlink

syzbot
2025-10-24T01:49:05Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in l2cap_conn_del

(syz-executor,6305,1):ocfs2_read_locked_inode:597 ERROR: status = -117
(syz-executor,6305,1):ocfs2_validate_inode_block:1465 ERROR: Invalid dinode #17057: i_mode is zero!
(syz-executor,6305,1):ocfs2_read_locked_inode:597 ERROR: status = -117
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/6305 is trying to acquire lock:
ffff88802ed7c040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
ffff88802ed7c040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
ffff88802ed7c040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4179 [inline]
ffff88802ed7c040 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}, at: __flush_work+0xd2/0xbc0 kernel/workqueue.c:4237

but task is already holding lock:
ffff88802ed7c338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1762

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 (&conn->lock#2){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__mutex_lock_common kernel/locking/mutex.c:598 [inline]
__mutex_lock+0x17d/0x12e0 kernel/locking/mutex.c:760
l2cap_info_timeout+0x60/0xa0 net/bluetooth/l2cap_core.c:1668
process_one_work kernel/workqueue.c:3263 [inline]
process_scheduled_works+0xa55/0x16b0 kernel/workqueue.c:3346
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #0 ((work_completion)(&(&conn->info_timer)->work)){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
touch_work_lockdep_map kernel/workqueue.c:3951 [inline]
start_flush_work kernel/workqueue.c:4205 [inline]
__flush_work+0x6b8/0xbc0 kernel/workqueue.c:4237
__cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4393
l2cap_conn_del+0x4f0/0x680 net/bluetooth/l2cap_core.c:1796
hci_disconn_cfm include/net/bluetooth/hci_core.h:2121 [inline]
hci_conn_hash_flush+0x10d/0x230 net/bluetooth/hci_conn.c:2602
hci_dev_close_sync+0xa0a/0x11b0 net/bluetooth/hci_sync.c:5303
hci_dev_do_close net/bluetooth/hci_core.c:501 [inline]
hci_unregister_dev+0x21a/0x510 net/bluetooth/hci_core.c:2715
vhci_release+0x152/0x1a0 drivers/bluetooth/hci_vhci.c:690
__fput+0x44c/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x6b5/0x2300 kernel/exit.c:966
do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
__do_sys_exit_group kernel/exit.c:1118 [inline]
__se_sys_exit_group kernel/exit.c:1116 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116
x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&conn->lock#2);
lock((work_completion)(&(&conn->info_timer)->work));
lock(&conn->lock#2);
lock((work_completion)(&(&conn->info_timer)->work));

*** DEADLOCK ***

5 locks held by syz-executor/6305:
#0: ffff888026654dc8 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_close net/bluetooth/hci_core.c:499 [inline]
#0: ffff888026654dc8 (&hdev->req_lock){+.+.}-{4:4}, at: hci_unregister_dev+0x212/0x510 net/bluetooth/hci_core.c:2715
#1: ffff8880266540b8 (&hdev->lock){+.+.}-{4:4}, at: hci_dev_close_sync+0x5b3/0x11b0 net/bluetooth/hci_sync.c:5291
#2: ffffffff8f1f8ca8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_disconn_cfm include/net/bluetooth/hci_core.h:2118 [inline]
#2: ffffffff8f1f8ca8 (hci_cb_list_lock){+.+.}-{4:4}, at: hci_conn_hash_flush+0xa1/0x230 net/bluetooth/hci_conn.c:2602
#3: ffff88802ed7c338 (&conn->lock#2){+.+.}-{4:4}, at: l2cap_conn_del+0x70/0x680 net/bluetooth/l2cap_core.c:1762
#4: ffffffff8dd3cc20 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#4: ffffffff8dd3cc20 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#4: ffffffff8dd3cc20 (rcu_read_lock){....}-{1:3}, at: start_flush_work kernel/workqueue.c:4179 [inline]
#4: ffffffff8dd3cc20 (rcu_read_lock){....}-{1:3}, at: __flush_work+0xd2/0xbc0 kernel/workqueue.c:4237

stack backtrace:
CPU: 0 UID: 0 PID: 6305 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
touch_work_lockdep_map kernel/workqueue.c:3951 [inline]
start_flush_work kernel/workqueue.c:4205 [inline]
__flush_work+0x6b8/0xbc0 kernel/workqueue.c:4237
__cancel_work_sync+0xbe/0x110 kernel/workqueue.c:4393
l2cap_conn_del+0x4f0/0x680 net/bluetooth/l2cap_core.c:1796
hci_disconn_cfm include/net/bluetooth/hci_core.h:2121 [inline]
hci_conn_hash_flush+0x10d/0x230 net/bluetooth/hci_conn.c:2602
hci_dev_close_sync+0xa0a/0x11b0 net/bluetooth/hci_sync.c:5303
hci_dev_do_close net/bluetooth/hci_core.c:501 [inline]
hci_unregister_dev+0x21a/0x510 net/bluetooth/hci_core.c:2715
vhci_release+0x152/0x1a0 drivers/bluetooth/hci_vhci.c:690
__fput+0x44c/0xa70 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x6b5/0x2300 kernel/exit.c:966
do_group_exit+0x21c/0x2d0 kernel/exit.c:1107
__do_sys_exit_group kernel/exit.c:1118 [inline]
__se_sys_exit_group kernel/exit.c:1116 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1116
x64_sys_call+0x21f7/0x2200 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7814385d29
Code: Unable to access opcode bytes at 0x7f7814385cff.
RSP: 002b:00007ffc212d6318 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f7814401919 RCX: 00007f7814385d29
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 000000000000000d R08: 00007ffc212d40b6 R09: 00007ffc212d75d0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc212d75d0
R13: 00007f78144018f4 R14: 00007ffc212d8690 R15: 0000000000000001
</TASK>

Tested on:

commit: 6fab32bb MAINTAINERS: add Mark Brown as a linux-next m..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=178fb734580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a1215729170d20fc
dashboard link: https://syzkaller.appspot.com/bug?extid=55c40ae8a0e5f3659f2b
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=1361c614580000