syzbot

gfs2: fsid=syz:syz.0: about to withdraw this file system
============================================
WARNING: possible recursive locking detected
5.15.174-syzkaller #0 Not tainted
--------------------------------------------
kworker/0:6/4216 is trying to acquire lock:
ffff88801ee6c938 ((wq_completion)delete_workqueue){+.+.}-{0:0}, at: flush_workqueue+0x154/0x1610 kernel/workqueue.c:2830

but task is already holding lock:
ffff88801ee6c938 ((wq_completion)delete_workqueue){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock((wq_completion)delete_workqueue);
  lock((wq_completion)delete_workqueue);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by kworker/0:6/4216:
 #0: ffff88801ee6c938 ((wq_completion)delete_workqueue){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283
 #1: ffffc900031dfd20 ((work_completion)(&(&gl->gl_delete)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285

stack backtrace:
CPU: 0 PID: 4216 Comm: kworker/0:6 Not tainted 5.15.174-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
Workqueue: delete_workqueue delete_work_func
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2946 [inline]
 check_deadlock kernel/locking/lockdep.c:2989 [inline]
 validate_chain+0x46d2/0x5930 kernel/locking/lockdep.c:3775
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 flush_workqueue+0x170/0x1610 kernel/workqueue.c:2830
 gfs2_make_fs_ro+0xd1/0x5f0 fs/gfs2/super.c:529
 signal_our_withdraw fs/gfs2/util.c:166 [inline]
 gfs2_withdraw+0x5fb/0x14e0 fs/gfs2/util.c:343
 gfs2_meta_check_ii+0x6e/0x80 fs/gfs2/util.c:498
 gfs2_metatype_check_i fs/gfs2/util.h:126 [inline]
 gfs2_meta_buffer+0x324/0x410 fs/gfs2/meta_io.c:493
 gfs2_meta_inode_buffer fs/gfs2/meta_io.h:70 [inline]
 gfs2_inode_refresh+0xdd/0x1070 fs/gfs2/glops.c:481
 gfs2_inode_lookup+0x86e/0xd10 fs/gfs2/inode.c:199
 gfs2_lookup_by_inum+0x4d/0xe0 fs/gfs2/inode.c:250
 delete_work_func+0x172/0x560 fs/gfs2/glock.c:1004
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>