============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G             L     
--------------------------------------------
kworker/0:5/5730 is trying to acquire lock:
ffff888032263928 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline]
ffff888032263928 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline]
ffff888032263928 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40 sound/core/seq/seq_clientmgr.c:813

but task is already holding lock:
ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline]
ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline]
ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40 sound/core/seq/seq_clientmgr.c:813

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

locks held by kworker/0:5/5730: 3, last CPU#0:
 #0: ffff88801b027140 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff88801b027140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa1a/0x14c0 kernel/workqueue.c:3405
 #1: ffffc90004c4fc40 ((work_completion)(&runtime->event_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffffc90004c4fc40 ((work_completion)(&runtime->event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa1a/0x14c0 kernel/workqueue.c:3405
 #2: ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline]
 #2: ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline]
 #2: ffff888052508928 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40 sound/core/seq/seq_clientmgr.c:813

stack backtrace:
CPU: 0 UID: 0 PID: 5730 Comm: kworker/0:5 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: events snd_rawmidi_input_event_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3057
 check_deadlock kernel/locking/lockdep.c:3109 [inline]
 validate_chain kernel/locking/lockdep.c:3911 [inline]
 __lock_acquire+0x24df/0x2cf0 kernel/locking/lockdep.c:5253
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886
 __raw_read_lock include/linux/rwlock_api_smp.h:163 [inline]
 _raw_read_lock+0x36/0x50 kernel/locking/spinlock.c:263
 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:723 [inline]
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline]
 snd_seq_deliver_event+0x241/0xa40 sound/core/seq/seq_clientmgr.c:813
 snd_seq_kernel_client_dispatch+0x201/0x310 sound/core/seq/seq_clientmgr.c:2439
 queue_broadcast_event sound/core/seq/seq_queue.c:585 [inline]
 snd_seq_queue_process_event sound/core/seq/seq_queue.c:601 [inline]
 snd_seq_control_queue+0x898/0x10f0 sound/core/seq/seq_queue.c:659
 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:626 [inline]
 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:672 [inline]
 snd_seq_deliver_single_event+0x568/0xc40 sound/core/seq/seq_clientmgr.c:687
 snd_seq_deliver_event+0x26a/0xa40 sound/core/seq/seq_clientmgr.c:815
 snd_seq_kernel_client_dispatch+0x201/0x310 sound/core/seq/seq_clientmgr.c:2439
 send_timer_event sound/core/seq/oss/seq_oss_timer.c:140 [inline]
 snd_seq_oss_timer_start+0x336/0x580 sound/core/seq/oss/seq_oss_timer.c:161
 send_midi_event sound/core/seq/oss/seq_oss_midi.c:576 [inline]
 snd_seq_oss_midi_input+0x50a/0xad0 sound/core/seq/oss/seq_oss_midi.c:501
 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:626 [inline]
 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:672 [inline]
 snd_seq_deliver_single_event+0x568/0xc40 sound/core/seq/seq_clientmgr.c:687
 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:735 [inline]
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:763 [inline]
 snd_seq_deliver_event+0x543/0xa40 sound/core/seq/seq_clientmgr.c:813
 snd_seq_kernel_client_dispatch+0x201/0x310 sound/core/seq/seq_clientmgr.c:2439
 snd_midi_input_event+0x2b1/0x400 sound/core/seq/seq_midi.c:93
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa88/0x14c0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>