------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common kernel/locking/mutex.c:625 [inline], CPU#1: syz.0.2192/15952
WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x944/0x1bd0 kernel/locking/mutex.c:821, CPU#1: syz.0.2192/15952
Modules linked in:
CPU: 1 UID: 0 PID: 15952 Comm: syz.0.2192 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
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:625 [inline]
RIP: 0010:__mutex_lock+0x94b/0x1bd0 kernel/locking/mutex.c:821
Code: 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 c0 10 00 00 44 8b 05 88 0e 73 05 45 85 c0 75 13 48 8d 3d 4c 19 76 05 48 c7 c6 20 f6 ef 8b <67> 48 0f b9 3a 90 e9 1b f8 ff ff 4d 8d a7 f0 0a 00 00 4c 89 e7 e8
RSP: 0018:ffffc9000506f800 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff8880284151c0 RCX: 1ffffffff228aa80
RDX: 0000000000000000 RSI: ffffffff8beff620 RDI: ffffffff91485ed0
RBP: ffffc9000506f970 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88802767c360
FS:  0000000000000000(0000) GS:ffff8880d5c5c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000560e12a47da8 CR3: 000000002e8f5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 virtio_gpu_remove_from_restore_list drivers/gpu/drm/virtio/virtgpu_object.c:70 [inline]
 virtio_gpu_free_object+0xec/0x280 drivers/gpu/drm/virtio/virtgpu_object.c:106
 drm_gem_object_free+0x60/0xa0 drivers/gpu/drm/drm_gem.c:1164
 kref_put include/linux/kref.h:65 [inline]
 __drm_gem_object_put include/drm/drm_gem.h:562 [inline]
 drm_gem_object_put include/drm/drm_gem.h:575 [inline]
 drm_gem_object_put include/drm/drm_gem.h:572 [inline]
 drm_client_buffer_delete drivers/gpu/drm/drm_client.c:201 [inline]
 drm_client_buffer_delete+0x1d8/0x270 drivers/gpu/drm/drm_client.c:185
 drm_fbdev_shmem_fb_destroy+0xc5/0x110 drivers/gpu/drm/drm_fbdev_shmem.c:67
 put_fb_info drivers/video/fbdev/core/fbmem.c:61 [inline]
 put_fb_info+0xb8/0xf0 drivers/video/fbdev/core/fbmem.c:56
 fb_release+0x13e/0x190 drivers/video/fbdev/core/fb_chrdev.c:381
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x951/0x2ae0 kernel/exit.c:1011
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1154
 get_signal+0x1ec7/0x21e0 kernel/signal.c:3051
 arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x139/0x700 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x661/0x790 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f501295e98e
Code: Unable to access opcode bytes at 0x7f501295e964.
RSP: 002b:00007fff440996d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e6
RAX: fffffffffffffdfc RBX: 000055558c685500 RCX: 00007f501295e98e
RDX: 00007fff44099730 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f5012c27da0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000003b239
R13: 00007f5012c2609c R14: 000000000003a6b3 R15: 00007f5012c26090
 </TASK>
----------------
Code disassembly (best guess):
   0:	0f b6 14 11          	movzbl (%rcx,%rdx,1),%edx
   4:	38 d0                	cmp    %dl,%al
   6:	7c 08                	jl     0x10
   8:	84 d2                	test   %dl,%dl
   a:	0f 85 c0 10 00 00    	jne    0x10d0
  10:	44 8b 05 88 0e 73 05 	mov    0x5730e88(%rip),%r8d        # 0x5730e9f
  17:	45 85 c0             	test   %r8d,%r8d
  1a:	75 13                	jne    0x2f
  1c:	48 8d 3d 4c 19 76 05 	lea    0x576194c(%rip),%rdi        # 0x576196f
  23:	48 c7 c6 20 f6 ef 8b 	mov    $0xffffffff8beff620,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	90                   	nop
  30:	e9 1b f8 ff ff       	jmp    0xfffff850
  35:	4d 8d a7 f0 0a 00 00 	lea    0xaf0(%r15),%r12
  3c:	4c 89 e7             	mov    %r12,%rdi
  3f:	e8                   	.byte 0xe8