Re: [syzbot] [dri?] WARNING in __drm_atomic_helper_set_config

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    08dbfad3f504 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13380349580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f
dashboard link: https://syzkaller.appspot.com/bug?extid=ca23c8570669ead78867
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=17392379580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17380349580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e64f94ffb05c/disk-08dbfad3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/36a861364fe8/vmlinux-08dbfad3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6130bd19ca7f/bzImage-08dbfad3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ca23c8570669ead78867@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
!set->fb
WARNING: drivers/gpu/drm/drm_atomic.c:2031 at __drm_atomic_helper_set_config+0xa45/0xee0 drivers/gpu/drm/drm_atomic.c:2031, CPU#1: syz-executor419/5624
Modules linked in:
CPU: 1 UID: 0 PID: 5624 Comm: syz-executor419 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__drm_atomic_helper_set_config+0xa45/0xee0 drivers/gpu/drm/drm_atomic.c:2031
Code: 84 c0 74 09 3c 03 7f 05 e8 28 6e b4 fc 45 89 75 38 e9 0e fb ff ff e8 6a 5b 41 fc 90 0f 0b 90 e9 9f f7 ff ff e8 5c 5b 41 fc 90 <0f> 0b 90 e9 47 f7 ff ff 8b 6c 24 28 e8 4a 5b 41 fc 49 8d 7c 24 08
RSP: 0018:ffffc900036d7890 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880349c1000 RCX: 0000000000000000
RDX: ffff88802f3dcb00 RSI: ffffffff85ca8bd4 RDI: ffff88802f3dcb00
RBP: ffff8880315d3800 R08: 0000000000000007 R09: fffffffffffff000
R10: ffff888028212c00 R11: 0000000000000000 R12: ffff88801c14e400
R13: ffff888028212c00 R14: ffff888028210c00 R15: ffff8880332d5328
FS:  0000000000000000(0000) GS:ffff888123c64000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcfbaa06a8 CR3: 0000000033c3a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 drm_client_modeset_commit_atomic+0x53d/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1085
 drm_client_modeset_commit_locked+0x14d/0x580 drivers/gpu/drm/drm_client_modeset.c:1207
 drm_client_modeset_commit+0x4f/0x80 drivers/gpu/drm/drm_client_modeset.c:1233
 __drm_fb_helper_restore_fbdev_mode_unlocked.part.0+0x137/0x160 drivers/gpu/drm/drm_fb_helper.c:138
 __drm_fb_helper_restore_fbdev_mode_unlocked drivers/gpu/drm/drm_fb_helper.c:126 [inline]
 drm_fb_helper_restore_fbdev_mode_unlocked+0x93/0xc0 drivers/gpu/drm/drm_fb_helper.c:169
 drm_fbdev_client_restore+0x1b/0x30 drivers/gpu/drm/clients/drm_fbdev_client.c:45
 drm_client_dev_restore+0x205/0x2a0 drivers/gpu/drm/drm_client_event.c:118
 drm_lastclose drivers/gpu/drm/drm_file.c:408 [inline]
 drm_release+0x2c6/0x360 drivers/gpu/drm/drm_file.c:441
 __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:1008
 do_group_exit+0xd5/0x2a0 kernel/exit.c:1151
 __do_sys_exit_group kernel/exit.c:1162 [inline]
 __se_sys_exit_group kernel/exit.c:1160 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1160
 x64_sys_call+0x1567/0x1570 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2694f1eb65
Code: Unable to access opcode bytes at 0x7f2694f1eb3b.
RSP: 002b:00007ffcb598ab38 EFLAGS: 00000202 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f2694f1eb65
RDX: 00000000000000e7 RSI: ffffffffffffffd8 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007f2694fb7108 R14: 00007f2694fbc648 R15: 00007f2694fbc660
 </TASK>


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