============================================
WARNING: possible recursive locking detected
5.15.0-rc1-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.2/9051 is trying to acquire lock:
ffff888147a5c9c8 (&mixer->reg_mutex
){+.+.}-{3:3}
, at: snd_mixer_oss_set_volume sound/core/oss/mixer_oss.c:316 [inline]
, at: snd_mixer_oss_ioctl1+0x512/0x1470 sound/core/oss/mixer_oss.c:375

but task is already holding lock:
ffff888147a5c9c8
 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_set_volume sound/core/oss/mixer_oss.c:300 [inline]
 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_ioctl1+0x3c5/0x1470 sound/core/oss/mixer_oss.c:375

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

       CPU0
       ----
  lock(&mixer->reg_mutex);
  lock(&mixer->reg_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

1 lock held by syz-executor.2/9051:
 #0: ffff888147a5c9c8 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_set_volume sound/core/oss/mixer_oss.c:300 [inline]
 #0: ffff888147a5c9c8 (&mixer->reg_mutex){+.+.}-{3:3}, at: snd_mixer_oss_ioctl1+0x3c5/0x1470 sound/core/oss/mixer_oss.c:375

stack backtrace:
CPU: 1 PID: 9051 Comm: syz-executor.2 Not tainted 5.15.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x57/0x7d lib/dump_stack.c:106
 print_deadlock_bug kernel/locking/lockdep.c:2944 [inline]
 check_deadlock kernel/locking/lockdep.c:2987 [inline]
 validate_chain kernel/locking/lockdep.c:3776 [inline]
 __lock_acquire.cold+0x229/0x3ab kernel/locking/lockdep.c:5015
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 __mutex_lock_common kernel/locking/mutex.c:596 [inline]
 __mutex_lock+0x131/0x12f0 kernel/locking/mutex.c:729
 snd_mixer_oss_set_volume sound/core/oss/mixer_oss.c:316 [inline]
 snd_mixer_oss_ioctl1+0x512/0x1470 sound/core/oss/mixer_oss.c:375
 snd_mixer_oss_ioctl+0x32/0x60 sound/core/oss/mixer_oss.c:390
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x11f/0x190 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f70333cca39
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f7032b42188 EFLAGS: 00000246
 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f70334cff60 RCX: 00007f70333cca39
RDX: 0000000020000080 RSI: 00000000c0044d00 RDI: 0000000000000003
RBP: 00007f7033426e8f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffdb897cfaf R14: 00007f7032b42300 R15: 0000000000022000