======================================================
WARNING: possible circular locking dependency detected
5.12.0-rc4-syzkaller #0 Not tainted
------------------------------------------------------
kworker/0:1H/2919 is trying to acquire lock:
ffff88806c80a0e0 (&type->s_umount_key#67){+.+.}-{3:3}, at: freeze_super+0x41/0x330 fs/super.c:1664

but task is already holding lock:
ffffc90001407da8 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}:
       process_one_work+0x8fc/0x1600 kernel/workqueue.c:2251
       worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
       kthread+0x3b1/0x4a0 kernel/kthread.c:292
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

-> #1 ((wq_completion)glock_workqueue){+.+.}-{0:0}:
       flush_workqueue+0x110/0x13e0 kernel/workqueue.c:2786
       gfs2_gl_hash_clear+0xad/0x270 fs/gfs2/glock.c:1996
       gfs2_put_super+0x451/0x650 fs/gfs2/super.c:688
       generic_shutdown_super+0x144/0x370 fs/super.c:464
       kill_block_super+0x97/0xf0 fs/super.c:1394
       gfs2_kill_sb+0x104/0x160 fs/gfs2/ops_fstype.c:1685
       deactivate_locked_super+0x94/0x160 fs/super.c:335
       deactivate_super+0xad/0xd0 fs/super.c:366
       cleanup_mnt+0x3a3/0x530 fs/namespace.c:1136
       task_work_run+0xdd/0x1a0 kernel/task_work.c:140
       tracehook_notify_resume include/linux/tracehook.h:189 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
       exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
       __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
       syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
       entry_SYSCALL_64_after_hwframe+0x44/0xae

-> #0 (&type->s_umount_key#67){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:2936 [inline]
       check_prevs_add kernel/locking/lockdep.c:3059 [inline]
       validate_chain kernel/locking/lockdep.c:3674 [inline]
       __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4900
       lock_acquire kernel/locking/lockdep.c:5510 [inline]
       lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475
       down_write+0x92/0x150 kernel/locking/rwsem.c:1406
       freeze_super+0x41/0x330 fs/super.c:1664
       freeze_go_sync+0x1e2/0x330 fs/gfs2/glops.c:574
       do_xmote+0x2ff/0xbc0 fs/gfs2/glock.c:630
       run_queue+0x323/0x680 fs/gfs2/glock.c:767
       glock_work_func+0xff/0x3f0 fs/gfs2/glock.c:934
       process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
       worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
       kthread+0x3b1/0x4a0 kernel/kthread.c:292
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

other info that might help us debug this:

Chain exists of:
  &type->s_umount_key#67 --> (wq_completion)glock_workqueue --> (work_completion)(&(&gl->gl_work)->work)

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((work_completion)(&(&gl->gl_work)->work));
                               lock((wq_completion)glock_workqueue);
                               lock((work_completion)(&(&gl->gl_work)->work));
  lock(&type->s_umount_key#67);

 *** DEADLOCK ***

2 locks held by kworker/0:1H/2919:
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline]
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline]
 #0: ffff888018b33d38 ((wq_completion)glock_workqueue){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246
 #1: ffffc90001407da8 ((work_completion)(&(&gl->gl_work)->work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250

stack backtrace:
CPU: 0 PID: 2919 Comm: kworker/0:1H Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: glock_workqueue glock_work_func
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2127
 check_prev_add kernel/locking/lockdep.c:2936 [inline]
 check_prevs_add kernel/locking/lockdep.c:3059 [inline]
 validate_chain kernel/locking/lockdep.c:3674 [inline]
 __lock_acquire+0x2b14/0x54c0 kernel/locking/lockdep.c:4900
 lock_acquire kernel/locking/lockdep.c:5510 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5475
 down_write+0x92/0x150 kernel/locking/rwsem.c:1406
 freeze_super+0x41/0x330 fs/super.c:1664
 freeze_go_sync+0x1e2/0x330 fs/gfs2/glops.c:574
 do_xmote+0x2ff/0xbc0 fs/gfs2/glock.c:630
 run_queue+0x323/0x680 fs/gfs2/glock.c:767
 glock_work_func+0xff/0x3f0 fs/gfs2/glock.c:934
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294