* [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
@ 2026-05-26 5:55 syzbot
2026-05-26 6:08 ` Tetsuo Handa
0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2026-05-26 5:55 UTC (permalink / raw)
To: dakr, driver-core, gregkh, linux-kernel, linux-next, rafael, sfr,
syzkaller-bugs
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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
------------[ 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
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
2026-05-26 5:55 [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device syzbot
@ 2026-05-26 6:08 ` Tetsuo Handa
2026-05-26 7:19 ` Tetsuo Handa
0 siblings, 1 reply; 6+ messages in thread
From: Tetsuo Handa @ 2026-05-26 6:08 UTC (permalink / raw)
To: Zhang Yuwei
Cc: syzbot, dakr, driver-core, gregkh, linux-kernel, linux-next,
rafael, sfr, syzkaller-bugs
On 2026/05/26 14:55, syzbot wrote:
> 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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> class_for_each_device called for class 'devlink' before it was registered
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/base?id=1137838865bfc9a7cd5869c1dc5c22aa45ec12c8
Why "driver_deferred_probe_timeout * HZ" => "driver_deferred_probe_timeout" ?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
2026-05-26 6:08 ` Tetsuo Handa
@ 2026-05-26 7:19 ` Tetsuo Handa
2026-05-26 11:59 ` Tetsuo Handa
2026-05-26 12:02 ` Danilo Krummrich
0 siblings, 2 replies; 6+ messages in thread
From: Tetsuo Handa @ 2026-05-26 7:19 UTC (permalink / raw)
To: Zhang Yuwei, gregkh
Cc: syzbot, dakr, driver-core, linux-kernel, linux-next, rafael, sfr,
syzkaller-bugs
On 2026/05/26 15:08, Tetsuo Handa wrote:
> On 2026/05/26 14:55, syzbot wrote:
>> 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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
>>
>> ------------[ cut here ]------------
>> class_for_each_device called for class 'devlink' before it was registered
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/base?id=1137838865bfc9a7cd5869c1dc5c22aa45ec12c8
>
> Why "driver_deferred_probe_timeout * HZ" => "driver_deferred_probe_timeout" ?
>
Here is an analysis from Google AI mode regarding this problem: https://share.google/aimode/UO1WnoKPDSbyjY5Qj
Greg, can you immediately drop commit 1137838865bf ("driver core: Use mod_delayed_work to prevent
lost deferred probe work") so that syzbot can resume testing linux-next tree as soon as possible?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
2026-05-26 7:19 ` Tetsuo Handa
@ 2026-05-26 11:59 ` Tetsuo Handa
2026-05-26 12:03 ` Danilo Krummrich
2026-05-26 12:02 ` Danilo Krummrich
1 sibling, 1 reply; 6+ messages in thread
From: Tetsuo Handa @ 2026-05-26 11:59 UTC (permalink / raw)
To: Zhang Yuwei, gregkh, Mark Brown
Cc: syzbot, dakr, driver-core, linux-kernel, linux-next, rafael, sfr,
syzkaller-bugs
On 2026/05/26 16:19, Tetsuo Handa wrote:
> On 2026/05/26 15:08, Tetsuo Handa wrote:
>> On 2026/05/26 14:55, syzbot wrote:
>>> 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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
>>>
>>> ------------[ cut here ]------------
>>> class_for_each_device called for class 'devlink' before it was registered
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/base?id=1137838865bfc9a7cd5869c1dc5c22aa45ec12c8
>>
>> Why "driver_deferred_probe_timeout * HZ" => "driver_deferred_probe_timeout" ?
>>
>
> Here is an analysis from Google AI mode regarding this problem: https://share.google/aimode/UO1WnoKPDSbyjY5Qj
>
> Greg, can you immediately drop commit 1137838865bf ("driver core: Use mod_delayed_work to prevent
> lost deferred probe work") so that syzbot can resume testing linux-next tree as soon as possible?
>
Below diff was generated via conversation with AI Mode in Google Search, and
I agree that this diff should fix the problem. I'm waiting for Greg's response
on how to proceed. Mark, can you carry below diff as a hotfix for linux-next tree?
---
drivers/base/dd.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 172a02a438a2..265717a19b08 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -298,10 +298,14 @@ int driver_deferred_probe_check_state(struct device *dev)
}
EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
+static int deferred_probe_timeout_triggered __data_racy;
static void deferred_probe_timeout_work_func(struct work_struct *work)
{
struct device_private *p;
+ if (cmpxchg(&deferred_probe_timeout_triggered, 0, 1))
+ return;
+
fw_devlink_drivers_done();
driver_deferred_probe_timeout = 0;
@@ -323,8 +327,9 @@ void deferred_probe_extend_timeout(void)
* If the work hasn't been queued yet or if the work expired, don't
* start a new one.
*/
- if (mod_delayed_work(system_wq, &deferred_probe_timeout_work,
- driver_deferred_probe_timeout))
+ if (!deferred_probe_timeout_triggered &&
+ mod_delayed_work(system_wq, &deferred_probe_timeout_work,
+ driver_deferred_probe_timeout * HZ))
pr_debug("Extended deferred probe timeout by %d secs\n",
driver_deferred_probe_timeout);
}
@@ -357,10 +362,11 @@ static int deferred_probe_initcall(void)
driver_deferred_probe_trigger();
flush_work(&deferred_probe_work);
- if (driver_deferred_probe_timeout > 0) {
+ if (driver_deferred_probe_timeout > 0)
schedule_delayed_work(&deferred_probe_timeout_work,
driver_deferred_probe_timeout * HZ);
- }
+ else
+ deferred_probe_timeout_triggered = 1;
if (!IS_ENABLED(CONFIG_MODULES))
fw_devlink_probing_done();
--
2.54.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
2026-05-26 7:19 ` Tetsuo Handa
2026-05-26 11:59 ` Tetsuo Handa
@ 2026-05-26 12:02 ` Danilo Krummrich
1 sibling, 0 replies; 6+ messages in thread
From: Danilo Krummrich @ 2026-05-26 12:02 UTC (permalink / raw)
To: Tetsuo Handa
Cc: Zhang Yuwei, gregkh, syzbot, driver-core, linux-kernel,
linux-next, rafael, sfr, syzkaller-bugs
On Tue May 26, 2026 at 9:19 AM CEST, Tetsuo Handa wrote:
> On 2026/05/26 15:08, Tetsuo Handa wrote:
>> On 2026/05/26 14:55, syzbot wrote:
>>> 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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
>>>
>>> ------------[ cut here ]------------
>>> class_for_each_device called for class 'devlink' before it was registered
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/base?id=1137838865bfc9a7cd5869c1dc5c22aa45ec12c8
>>
>> Why "driver_deferred_probe_timeout * HZ" => "driver_deferred_probe_timeout" ?
>>
>
> Here is an analysis from Google AI mode regarding this problem: https://share.google/aimode/UO1WnoKPDSbyjY5Qj
>
> Greg, can you immediately drop commit 1137838865bf ("driver core: Use mod_delayed_work to prevent
> lost deferred probe work") so that syzbot can resume testing linux-next tree as soon as possible?
I already posted patches to fix this in [1]. I will pick them up today.
[1] https://lore.kernel.org/driver-core/20260525012340.3860581-1-dakr@kernel.org/t/#u
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device
2026-05-26 11:59 ` Tetsuo Handa
@ 2026-05-26 12:03 ` Danilo Krummrich
0 siblings, 0 replies; 6+ messages in thread
From: Danilo Krummrich @ 2026-05-26 12:03 UTC (permalink / raw)
To: Tetsuo Handa
Cc: Zhang Yuwei, gregkh, Mark Brown, syzbot, driver-core,
linux-kernel, linux-next, rafael, sfr, syzkaller-bugs
On Tue May 26, 2026 at 1:59 PM CEST, Tetsuo Handa wrote:
> On 2026/05/26 16:19, Tetsuo Handa wrote:
>> On 2026/05/26 15:08, Tetsuo Handa wrote:
>>> On 2026/05/26 14:55, syzbot wrote:
>>>> 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: syzbot+50b5f81fff158669504a@syzkaller.appspotmail.com
>>>>
>>>> ------------[ cut here ]------------
>>>> class_for_each_device called for class 'devlink' before it was registered
>>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/base?id=1137838865bfc9a7cd5869c1dc5c22aa45ec12c8
>>>
>>> Why "driver_deferred_probe_timeout * HZ" => "driver_deferred_probe_timeout" ?
>>>
>>
>> Here is an analysis from Google AI mode regarding this problem: https://share.google/aimode/UO1WnoKPDSbyjY5Qj
>>
>> Greg, can you immediately drop commit 1137838865bf ("driver core: Use mod_delayed_work to prevent
>> lost deferred probe work") so that syzbot can resume testing linux-next tree as soon as possible?
>>
>
> Below diff was generated via conversation with AI Mode in Google Search, and
> I agree that this diff should fix the problem. I'm waiting for Greg's response
> on how to proceed. Mark, can you carry below diff as a hotfix for linux-next tree?
As mentioned in the previous reply, I already posted patches for this in [1];
will pick them up today.
[1] https://lore.kernel.org/driver-core/20260525012340.3860581-1-dakr@kernel.org/t/#u
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-05-26 12:03 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-05-26 5:55 [syzbot] [kernel?] linux-next test error: WARNING in class_for_each_device syzbot
2026-05-26 6:08 ` Tetsuo Handa
2026-05-26 7:19 ` Tetsuo Handa
2026-05-26 11:59 ` Tetsuo Handa
2026-05-26 12:03 ` Danilo Krummrich
2026-05-26 12:02 ` Danilo Krummrich
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox