============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
kworker/0:18/4320 is trying to acquire lock:
ffff88802af0a130 (&grp->list_lock){.+.+}-{2:2}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
ffff88802af0a130 (&grp->list_lock){.+.+}-{2:2}, at: snd_seq_deliver_event+0x1cb/0x8c0 sound/core/seq/seq_clientmgr.c:854

but task is already holding lock:
ffff88802070f930 (&grp->list_lock){.+.+}-{2:2}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
ffff88802070f930 (&grp->list_lock){.+.+}-{2:2}, at: snd_seq_deliver_event+0x1cb/0x8c0 sound/core/seq/seq_clientmgr.c:854

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

       CPU0
       ----
  lock(&grp->list_lock);
  lock(&grp->list_lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by kworker/0:18/4320:
 #0: ffff888016c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90003defd00 ((work_completion)(&runtime->event_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
 #2: ffff88802070f930 (&grp->list_lock){.+.+}-{2:2}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
 #2: ffff88802070f930 (&grp->list_lock){.+.+}-{2:2}, at: snd_seq_deliver_event+0x1cb/0x8c0 sound/core/seq/seq_clientmgr.c:854

stack backtrace:
CPU: 0 PID: 4320 Comm: kworker/0:18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events snd_rawmidi_input_event_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 __lock_acquire+0x1247/0x7b50 kernel/locking/lockdep.c:-1
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __raw_read_lock include/linux/rwlock_api_smp.h:149 [inline]
 _raw_read_lock+0x32/0x40 kernel/locking/spinlock.c:228
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
 snd_seq_deliver_event+0x1cb/0x8c0 sound/core/seq/seq_clientmgr.c:854
 snd_seq_kernel_client_dispatch+0x1fc/0x2f0 sound/core/seq/seq_clientmgr.c:2407
 queue_broadcast_event sound/core/seq/seq_queue.c:645 [inline]
 snd_seq_queue_process_event sound/core/seq/seq_queue.c:661 [inline]
 snd_seq_control_queue+0x8ff/0x1010 sound/core/seq/seq_queue.c:721
 snd_seq_deliver_single_event+0x806/0xb30 sound/core/seq/seq_clientmgr.c:663
 snd_seq_kernel_client_dispatch+0x1fc/0x2f0 sound/core/seq/seq_clientmgr.c:2407
 send_timer_event sound/core/seq/oss/seq_oss_timer.c:140 [inline]
 snd_seq_oss_timer_start+0x2ce/0x510 sound/core/seq/oss/seq_oss_timer.c:161
 send_midi_event sound/core/seq/oss/seq_oss_midi.c:622 [inline]
 snd_seq_oss_midi_input+0x2e8/0x890 sound/core/seq/oss/seq_oss_midi.c:544
 snd_seq_deliver_single_event+0x806/0xb30 sound/core/seq/seq_clientmgr.c:663
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:720 [inline]
 snd_seq_deliver_event+0x49d/0x8c0 sound/core/seq/seq_clientmgr.c:854
 snd_seq_kernel_client_dispatch+0x1fc/0x2f0 sound/core/seq/seq_clientmgr.c:2407
 snd_midi_input_event+0x289/0x3d0 sound/core/seq/seq_midi.c:89
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>