Re: Policy regarding linux-next only changes

[Tetsuo Handa]

On 2026/07/29 7:11, Miguel Ojeda wrote:
> On Tue, Jul 28, 2026 at 4:46 PM Tetsuo Handa
> <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
>>
>> syzbot stops upon encountering "BUG:" or "WARNING:" within printk() output.
> 
> Out of curiosity, is that a fundamental property or something that
> could be optionally be relaxed (for certain linux-next runs only,
> perhaps) so that you can continue testing in certain cases where the
> "WARNING:" may be harmless (i.e. irrelevant for your particular
> fuzzing)?
> 
> i.e. I was wondering whether the system could ignore the "WARNING:"s
> (and avoid the kernel panicking on them etc.) until after boot, i.e.
> when the fuzzing starts.

syzbot uses kernel.panic_on_warn=1, for most of WARN*() users are reporting
problems that should not be ignored. Therefore, WARN*() must not be used for
reporting recoverable mistakes like -EINVAL. Abusing WARN*() like
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/kernel/workqueue.c?id=6e845bcb78c95af935094040bd4edc3c2b6dd784#n5855
is a fatal barrier for continuous testing systems like syzbot.

Quoting from https://lkml.kernel.org/r/5b2dea50-2850-4876-b6e8-ba94b9a85034@xxxxxxxxxxxxxxxxxxx :

  Please never try to emit WARNING: or BUG: message just for letting developers
  update their code. If you can't use panic() instead of WARN*() or BUG*(), you
  should not use WARN*() or BUG*(). The patch author who changes the behavior of
  in-tree code is responsible for updating all in-tree code.

Commit 860e748bddcc ("drm: ensure blend mode supported if pixel format
with alpha exposed") must be reverted or updated not to emit "WARNING:" string.
Until authors of that commit respond, that commit had better be excluded from
the linux-next tree.