* [syzbot] [dri?] WARNING in drm_atomic_helper_wait_for_vblanks (6)
@ 2026-05-27 22:06 syzbot
2026-08-10 1:07 ` syzbot
0 siblings, 1 reply; 2+ messages in thread
From: syzbot @ 2026-05-27 22:06 UTC (permalink / raw)
To: airlied, dri-devel, linux-kernel, maarten.lankhorst, mripard,
simona, syzkaller-bugs, tzimmermann
Hello,
syzbot found the following issue on:
HEAD commit: 79bd2dded182 Merge tag 'sched_ext-for-7.1-rc4-fixes' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12282ac8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e327ee9a867dd6b9
dashboard link: https://syzkaller.appspot.com/bug?extid=45bc7264de77caad91cb
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-79bd2dde.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/334fd806b634/vmlinux-79bd2dde.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dc1d1c63d028/bzImage-79bd2dde.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+45bc7264de77caad91cb@syzkaller.appspotmail.com
------------[ cut here ]------------
[CRTC:39:crtc-0] vblank wait timed out
WARNING: drivers/gpu/drm/drm_atomic_helper.c:1921 at drm_atomic_helper_wait_for_vblanks.part.0+0x738/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1921, CPU#1: kworker/1:1/54
Modules linked in:
CPU: 1 UID: 0 PID: 54 Comm: kworker/1:1 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
Workqueue: events drm_fb_helper_damage_work
RIP: 0010:drm_atomic_helper_wait_for_vblanks.part.0+0x73e/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1921
Code: 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 04 01 84 c0 74 08 3c 03 0f 8e 44 01 00 00 48 8d 3d e8 b2 3a 0b 8b b3 d0 00 00 00 <67> 48 0f b9 3a e9 e1 fc ff ff e8 43 4e 60 fc e9 7c fe ff ff e8 e9
RSP: 0018:ffffc90000a7f6e8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888100fa0040 RCX: 1ffff110201f4022
RDX: ffff888025b8c780 RSI: 0000000000000027 RDI: ffffffff90e31630
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802a6c0200
FS: 0000000000000000(0000) GS:ffff8880d646a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fea94fea540 CR3: 000000002e244000 CR4: 0000000000352ef0
Call Trace:
<TASK>
drm_atomic_helper_wait_for_vblanks drivers/gpu/drm/drm_atomic_helper.c:1895 [inline]
drm_atomic_helper_commit_tail+0xff/0x130 drivers/gpu/drm/drm_atomic_helper.c:1997
commit_tail+0x338/0x430 drivers/gpu/drm/drm_atomic_helper.c:2074
drm_atomic_helper_commit+0x303/0x380 drivers/gpu/drm/drm_atomic_helper.c:2312
drm_atomic_commit+0x230/0x300 drivers/gpu/drm/drm_atomic.c:1789
drm_atomic_helper_dirtyfb+0x603/0x790 drivers/gpu/drm/drm_damage_helper.c:183
drm_fbdev_shmem_helper_fb_dirty+0x1cc/0x310 drivers/gpu/drm/drm_fbdev_shmem.c:117
drm_fb_helper_fb_dirty drivers/gpu/drm/drm_fb_helper.c:249 [inline]
drm_fb_helper_damage_work+0x348/0x640 drivers/gpu/drm/drm_fb_helper.c:275
process_one_work+0xa0e/0x1980 kernel/workqueue.c:3314
process_scheduled_works kernel/workqueue.c:3397 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3478
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 fc add %bh,%ah
4: ff lcall (bad)
5: df 48 89 fisttps -0x77(%rax)
8: f9 stc
9: 48 c1 e9 03 shr $0x3,%rcx
d: 0f b6 04 01 movzbl (%rcx,%rax,1),%eax
11: 84 c0 test %al,%al
13: 74 08 je 0x1d
15: 3c 03 cmp $0x3,%al
17: 0f 8e 44 01 00 00 jle 0x161
1d: 48 8d 3d e8 b2 3a 0b lea 0xb3ab2e8(%rip),%rdi # 0xb3ab30c
24: 8b b3 d0 00 00 00 mov 0xd0(%rbx),%esi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: e9 e1 fc ff ff jmp 0xfffffd15
34: e8 43 4e 60 fc call 0xfc604e7c
39: e9 7c fe ff ff jmp 0xfffffeba
3e: e8 .byte 0xe8
3f: e9 .byte 0xe9
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot will keep track of this issue. See:
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If the report is already addressed, let syzbot know by replying with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [syzbot] [dri?] WARNING in drm_atomic_helper_wait_for_vblanks (6)
2026-05-27 22:06 [syzbot] [dri?] WARNING in drm_atomic_helper_wait_for_vblanks (6) syzbot
@ 2026-08-10 1:07 ` syzbot
0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2026-08-10 1:07 UTC (permalink / raw)
To: airlied, dri-devel, linux-kernel, maarten.lankhorst, mripard,
simona, syzkaller-bugs, tzimmermann
syzbot has found a reproducer for the following issue on:
HEAD commit: b643e495ae92 Merge tag 's390-7.2-7' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=176c0079580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c44651ea7dd2f307
dashboard link: https://syzkaller.appspot.com/bug?extid=45bc7264de77caad91cb
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15cbc079580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=138fa2c6580000
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-b643e495.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9eb4fbda136d/vmlinux-b643e495.xz
kernel image: https://storage.googleapis.com/syzbot-assets/53cbbd75c40a/bzImage-b643e495.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+45bc7264de77caad91cb@syzkaller.appspotmail.com
------------[ cut here ]------------
[CRTC:39:crtc-0] vblank wait timed out
WARNING: drivers/gpu/drm/drm_atomic_helper.c:1921 at drm_atomic_helper_wait_for_vblanks.part.0+0x738/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1921, CPU#3: syz.0.17/5906
Modules linked in:
CPU: 3 UID: 0 PID: 5906 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:drm_atomic_helper_wait_for_vblanks.part.0+0x73e/0x8a0 drivers/gpu/drm/drm_atomic_helper.c:1921
Code: 00 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 04 01 84 c0 74 08 3c 03 0f 8e 44 01 00 00 48 8d 3d 48 de 5f 0b 8b b3 d0 00 00 00 <67> 48 0f b9 3a e9 e1 fc ff ff e8 93 10 3d fc e9 7c fe ff ff e8 99
RSP: 0018:ffffc90003847710 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888028680040 RCX: 1ffff110050d0022
RDX: ffff8880285a50e0 RSI: 0000000000000027 RDI: ffffffff912d4120
RBP: dffffc0000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802e1f5000
FS: 000055557c115500(0000) GS:ffff8880d60ec000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055777c801168 CR3: 000000005176b000 CR4: 0000000000352ef0
Call Trace:
<TASK>
drm_atomic_helper_wait_for_vblanks drivers/gpu/drm/drm_atomic_helper.c:1895 [inline]
drm_atomic_helper_commit_tail+0xff/0x130 drivers/gpu/drm/drm_atomic_helper.c:1997
commit_tail+0x338/0x430 drivers/gpu/drm/drm_atomic_helper.c:2074
drm_atomic_helper_commit+0x303/0x380 drivers/gpu/drm/drm_atomic_helper.c:2312
drm_atomic_commit+0x230/0x300 drivers/gpu/drm/drm_atomic.c:1789
drm_atomic_helper_set_config+0x13a/0x190 drivers/gpu/drm/drm_atomic_helper.c:3523
drm_mode_setcrtc+0xeca/0x1d50 drivers/gpu/drm/drm_crtc.c:885
drm_ioctl_kernel+0x1f3/0x3e0 drivers/gpu/drm/drm_ioctl.c:817
drm_ioctl+0x5e6/0xc60 drivers/gpu/drm/drm_ioctl.c:914
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6d5bf9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe900c07d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6d5c225fa0 RCX: 00007f6d5bf9e0d9
RDX: 0000200000000300 RSI: 00000000c06864a2 RDI: 0000000000000003
RBP: 00007f6d5c035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6d5c225fac R14: 00007f6d5c225fa0 R15: 00007f6d5c225fa0
</TASK>
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: 00 fc add %bh,%ah
4: ff lcall (bad)
5: df 48 89 fisttps -0x77(%rax)
8: f9 stc
9: 48 c1 e9 03 shr $0x3,%rcx
d: 0f b6 04 01 movzbl (%rcx,%rax,1),%eax
11: 84 c0 test %al,%al
13: 74 08 je 0x1d
15: 3c 03 cmp $0x3,%al
17: 0f 8e 44 01 00 00 jle 0x161
1d: 48 8d 3d 48 de 5f 0b lea 0xb5fde48(%rip),%rdi # 0xb5fde6c
24: 8b b3 d0 00 00 00 mov 0xd0(%rbx),%esi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: e9 e1 fc ff ff jmp 0xfffffd15
34: e8 93 10 3d fc call 0xfc3d10cc
39: e9 7c fe ff ff jmp 0xfffffeba
3e: e8 .byte 0xe8
3f: 99 cltd
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
^ permalink raw reply [flat|nested] 2+ messages in thread
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