Subject: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device

From: syzbot <[email-masked]>
Date: Mon, 25 May 2026 22:55:34 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    d387b06f7c15 Add linux-next specific files for 20260525
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15eb7796580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8dd72cf810e753a6
dashboard link: https://syzkaller.appspot.com/bug?extid=50b5f81fff158669504a
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39490dfbc250/disk-d387b06f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0789ac7ac5fc/vmlinux-d387b06f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4464df9f5ccf/bzImage-d387b06f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

------------[ cut here ]------------
class_for_each_device called for class 'devlink' before it was registered
WARNING: drivers/base/class.c:416 at class_for_each_device+0x2d8/0x390 drivers/base/class.c:415, CPU#1: kworker/1:1/37
Modules linked in:
CPU: 1 UID: 0 PID: 37 Comm: kworker/1:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events deferred_probe_timeout_work_func
RIP: 0010:class_for_each_device+0x2fc/0x390 drivers/base/class.c:415
Code: 8d 1d 38 5c 0e 0a 4c 89 e8 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 ef e8 62 fc a5 fc 49 8b 55 00 48 89 df 48 c7 c6 f1 46 5d 8d <67> 48 0f b9 3a b8 ea ff ff ff eb 1b e8 93 79 3b fc 49 81 c6 90 00
RSP: 0000:ffffc90000ac7a20 EFLAGS: 00010246
RAX: 1ffffffff17865d4 RBX: ffffffff8f984790 RCX: ffff88801e2e9f00
RDX: ffffffff8bc34360 RSI: ffffffff8d5d46f1 RDI: ffffffff8f984790
RBP: ffffc90000ac7af8 R08: ffffc90000ac7a7f R09: 0000000000000000
R10: ffffc90000ac7a60 R11: fffff52000158f50 R12: ffffc90000ac7a60
R13: ffffffff8bc32ea0 R14: 1ffff92000158f48 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff888125fdb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000000ddb8000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 fw_devlink_drivers_done+0x35/0x50 drivers/base/core.c:1837
 deferred_probe_timeout_work_func+0x21/0x220 drivers/base/dd.c:305
 process_one_work+0x98b/0x1630 kernel/workqueue.c:3318
 process_scheduled_works kernel/workqueue.c:3401 [inline]
 worker_thread+0xb49/0x1140 kernel/workqueue.c:3482
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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:	8d 1d 38 5c 0e 0a    	lea    0xa0e5c38(%rip),%ebx        # 0xa0e5c3e
   6:	4c 89 e8             	mov    %r13,%rax
   9:	48 c1 e8 03          	shr    $0x3,%rax
   d:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1)
  12:	74 08                	je     0x1c
  14:	4c 89 ef             	mov    %r13,%rdi
  17:	e8 62 fc a5 fc       	call   0xfca5fc7e
  1c:	49 8b 55 00          	mov    0x0(%r13),%rdx
  20:	48 89 df             	mov    %rbx,%rdi
  23:	48 c7 c6 f1 46 5d 8d 	mov    $0xffffffff8d5d46f1,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	b8 ea ff ff ff       	mov    $0xffffffea,%eax
  34:	eb 1b                	jmp    0x51
  36:	e8 93 79 3b fc       	call   0xfc3b79ce
  3b:	49                   	rex.WB
  3c:	81                   	.byte 0x81
  3d:	c6                   	(bad)
  3e:	90                   	nop

---
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