============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G             L     
--------------------------------------------
kworker/0:11/11878 is trying to acquire lock:
ffff88810cc66928 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40

but task is already holding lock:
ffff88811141c128 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40

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/0:11/11878:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #1: ffffc900070e7c40 ((work_completion)(&runtime->event_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0
 #2: ffff88811141c128 (&grp->list_lock){.+.+}-{3:3}, at: snd_seq_deliver_event+0x241/0xa40

stack backtrace:
CPU: 0 UID: 0 PID: 11878 Comm: kworker/0:11 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events snd_rawmidi_input_event_work
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_deadlock_bug+0x279/0x290
 __lock_acquire+0x24df/0x2cf0
 lock_acquire+0x106/0x350
 _raw_read_lock+0x36/0x50
 snd_seq_deliver_event+0x241/0xa40
 snd_seq_kernel_client_dispatch+0x201/0x310
 snd_seq_control_queue+0x977/0x11b0
 snd_seq_deliver_single_event+0x568/0xc40
 snd_seq_deliver_event+0x26a/0xa40
 snd_seq_kernel_client_dispatch+0x201/0x310
 snd_seq_oss_timer_start+0x336/0x580
 snd_seq_oss_midi_input+0x332/0x9c0
 snd_seq_deliver_single_event+0x568/0xc40
 snd_seq_deliver_event+0x543/0xa40
 snd_seq_kernel_client_dispatch+0x201/0x310
 snd_midi_input_event+0x2b1/0x400
 process_scheduled_works+0xa8e/0x14e0
 worker_thread+0xa47/0xfb0
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
