WARNING: at drm_atomic_helper_wait_for_vblanks, CPU: kworker/NUM:NUM/NUM

[sanan.hasanou@gmail.com]

Good day, dear maintainers,

We found a bug using a modified version of syzkaller.

Kernel Branch: 7.0-rc1
Kernel Config: <https://drive.google.com/open?id=173DLEAEPKPhhR1TcqofdnkLpdoK7PMFl>
Unfortunately, we don't have any reproducer for this bug yet.
Thank you!

Best regards,
Sanan Hasanov

------------[ cut here ]------------
[CRTC:35:crtc-0] vblank wait timed out
WARNING: at drm_atomic_helper_wait_for_vblanks+0x764/0x8f0 drivers/gpu/drm/drm_atomic_helper.c:1921, CPU#1: kworker/1:1/30
Modules linked in:
CPU: 1 UID: 0 PID: 30 Comm: kworker/1:1 Not tainted 7.0.0-rc1 #1 PREEMPT(full) 
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:drm_atomic_helper_wait_for_vblanks+0x7b0/0x8f0 drivers/gpu/drm/drm_atomic_helper.c:1921
Code: 45 8b b6 88 00 00 00 4c 8d 68 20 4c 89 e8 48 c1 e8 03 80 3c 18 00 74 08 4c 89 ef e8 9a 83 f4 fc 49 8b 55 00 4c 89 ff 44 89 f6 <67> 48 0f b9 3a 4d 89 e5 e9 34 ff ff ff 44 89 f1 80 e1 07 80 c1 03
RSP: 0018:ffffc900002075a0 EFLAGS: 00010246
RAX: 1ffff11003a891c3 RBX: dffffc0000000000 RCX: ffff88801330e180
RDX: ffff88801c9712c0 RSI: 0000000000000023 RDI: ffffffff906b49a8
RBP: ffffc900002076e0 R08: ffff88801d478833 R09: 1ffff11003a8f106
R10: dffffc0000000000 R11: ffffed1003a8f107 R12: ffff88801ca0ec28
R13: ffff88801d448e18 R14: 0000000000000023 R15: ffffffff906b49a8
FS:  0000000000000000(0000) GS:ffff8880d99df000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000e6ff000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 drm_atomic_helper_commit_tail+0x2d2/0x4e0 drivers/gpu/drm/drm_atomic_helper.c:1997
 commit_tail+0x298/0x3a0 drivers/gpu/drm/drm_atomic_helper.c:2074
 drm_atomic_helper_commit+0xa2e/0xad0 drivers/gpu/drm/drm_atomic_helper.c:2312
 drm_atomic_commit+0x261/0x2c0 drivers/gpu/drm/drm_atomic.c:1775
 drm_atomic_helper_dirtyfb+0xdc0/0xf10 drivers/gpu/drm/drm_damage_helper.c:183
 drm_fbdev_shmem_helper_fb_dirty+0x161/0x2d0 drivers/gpu/drm/drm_fbdev_shmem.c:117
 drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:248 [inline]
 drm_fb_helper_damage_work+0x296/0x720 drivers/gpu/drm/drm_fb_helper.c:274
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0x811/0xf10 kernel/workqueue.c:3358
 worker_thread+0x9c1/0xeb0 kernel/workqueue.c:3439
 kthread+0x3c1/0x4d0 kernel/kthread.c:467
 ret_from_fork+0x608/0xc40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	45 8b b6 88 00 00 00 	mov    0x88(%r14),%r14d
   7:	4c 8d 68 20          	lea    0x20(%rax),%r13
   b:	4c 89 e8             	mov    %r13,%rax
   e:	48 c1 e8 03          	shr    $0x3,%rax
  12:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  16:	74 08                	je     0x20
  18:	4c 89 ef             	mov    %r13,%rdi
  1b:	e8 9a 83 f4 fc       	call   0xfcf483ba
  20:	49 8b 55 00          	mov    0x0(%r13),%rdx
  24:	4c 89 ff             	mov    %r15,%rdi
  27:	44 89 f6             	mov    %r14d,%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	4d 89 e5             	mov    %r12,%r13
  32:	e9 34 ff ff ff       	jmp    0xffffff6b
  37:	44 89 f1             	mov    %r14d,%ecx
  3a:	80 e1 07             	and    $0x7,%cl
  3d:	80 c1 03             	add    $0x3,%cl

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