genirq: Flags mismatch irq 4. 00200000 (pcl812) vs. 00200080 (ttyS0)
============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G             L     
--------------------------------------------
syz.9.5121/26098 is trying to acquire lock:
ffff88805085e160 (&rmidi->open_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
ffff88805085e160 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_kernel_open+0xa4/0x190 sound/core/rawmidi.c:422

but task is already holding lock:
ffff88804d313d60 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_open+0x296/0xba0 sound/core/rawmidi.c:467

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

       CPU0
       ----
  lock(&rmidi->open_mutex);
  lock(&rmidi->open_mutex);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

2 locks held by syz.9.5121/26098:
 #0: ffff88804d313d60 (&rmidi->open_mutex){+.+.}-{4:4}, at: snd_rawmidi_open+0x296/0xba0 sound/core/rawmidi.c:467
 #1: ffff88805085e460 (&ump->open_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #1: ffff88805085e460 (&ump->open_mutex){+.+.}-{4:4}, at: snd_ump_legacy_open+0x120/0x4e0 sound/core/ump.c:1153

stack backtrace:
CPU: 3 UID: 0 PID: 26098 Comm: syz.9.5121 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_deadlock_bug.cold+0xbd/0xca kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x1256/0x1a40 kernel/locking/lockdep.c:5237
 lock_acquire kernel/locking/lockdep.c:5868 [inline]
 lock_acquire+0x1b9/0x370 kernel/locking/lockdep.c:5825
 __mutex_lock_common kernel/locking/mutex.c:646 [inline]
 __mutex_lock+0x1a4/0x1bd0 kernel/locking/mutex.c:821
 class_mutex_constructor include/linux/mutex.h:253 [inline]
 snd_rawmidi_kernel_open+0xa4/0x190 sound/core/rawmidi.c:422
 snd_ump_legacy_open+0x367/0x4e0 sound/core/ump.c:1160
 open_substream+0x480/0x970 sound/core/rawmidi.c:348
 rawmidi_open_priv+0x595/0x6f0 sound/core/rawmidi.c:397
 snd_rawmidi_open+0x4c9/0xba0 sound/core/rawmidi.c:485
 snd_open+0x201/0x450 sound/core/sound.c:166
 chrdev_open+0x234/0x6a0 fs/char_dev.c:411
 do_dentry_open+0x6ab/0x14d0 fs/open.c:947
 vfs_open+0x82/0x3f0 fs/open.c:1052
 do_open fs/namei.c:4700 [inline]
 path_openat+0x2873/0x4280 fs/namei.c:4863
 do_file_open+0x20e/0x430 fs/namei.c:4892
 do_sys_openat2+0x10f/0x1e0 fs/open.c:1368
 do_sys_open fs/open.c:1374 [inline]
 __do_compat_sys_openat fs/open.c:1436 [inline]
 __se_compat_sys_openat fs/open.c:1434 [inline]
 __ia32_compat_sys_openat+0x12d/0x210 fs/open.c:1434
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 do_int80_emulation+0x14b/0x720 arch/x86/entry/syscall_32.c:172
 asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:598
RIP: 0023:0xf71e72eb
Code: 57 56 53 8b 44 24 14 f6 00 08 75 23 8b 44 24 18 8b 5c 24 1c 8b 4c 24 20 8b 54 24 24 8b 74 24 28 8b 7c 24 2c 8b 6c 24 30 cd 80 <5b> 5e 5f 5d c3 5b 5e 5f 5d e9 f7 a1 ff ff 66 90 66 90 66 90 90 53
RSP: 002b:00000000f549d03c EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 00000000ffffff9c RCX: 00000000f549d100
RDX: 0000000000141102 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess):
   0:	57                   	push   %rdi
   1:	56                   	push   %rsi
   2:	53                   	push   %rbx
   3:	8b 44 24 14          	mov    0x14(%rsp),%eax
   7:	f6 00 08             	testb  $0x8,(%rax)
   a:	75 23                	jne    0x2f
   c:	8b 44 24 18          	mov    0x18(%rsp),%eax
  10:	8b 5c 24 1c          	mov    0x1c(%rsp),%ebx
  14:	8b 4c 24 20          	mov    0x20(%rsp),%ecx
  18:	8b 54 24 24          	mov    0x24(%rsp),%edx
  1c:	8b 74 24 28          	mov    0x28(%rsp),%esi
  20:	8b 7c 24 2c          	mov    0x2c(%rsp),%edi
  24:	8b 6c 24 30          	mov    0x30(%rsp),%ebp
  28:	cd 80                	int    $0x80
* 2a:	5b                   	pop    %rbx <-- trapping instruction
  2b:	5e                   	pop    %rsi
  2c:	5f                   	pop    %rdi
  2d:	5d                   	pop    %rbp
  2e:	c3                   	ret
  2f:	5b                   	pop    %rbx
  30:	5e                   	pop    %rsi
  31:	5f                   	pop    %rdi
  32:	5d                   	pop    %rbp
  33:	e9 f7 a1 ff ff       	jmp    0xffffa22f
  38:	66 90                	xchg   %ax,%ax
  3a:	66 90                	xchg   %ax,%ax
  3c:	66 90                	xchg   %ax,%ax
  3e:	90                   	nop
  3f:	53                   	push   %rbx