Re: [7.0-rc1] codetag: kernel warning "alloc_tag was not set" during boot

[Suren Baghdasaryan]

On Mon, Feb 23, 2026 at 6:28 PM David Wang <00107082@xxxxxxx> wrote:
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> At 2026-02-24 01:18:32, "Vlastimil Babka" <vbabka@xxxxxxxx> wrote:
> >On 2/23/26 16:51, David Wang wrote:
> >> Hi,
> >>
> >> When upgrade to 7.0.0-rc1, caught a kernel WARN during boot:
> >
> >Would this possibly help? (it probably shouldn't but let's see)
> >https://lore.kernel.org/all/20260223075809.19265-1-harry.yoo@xxxxxxxxxx/
> >
>
> Hi,
> I tried this patch, but sadly, it doesn't help with the warning on my system...

Unfortunately I can't boot far enough with your config to get that warning.

You might be able to track down which allocation does not get its tag
by first checking for current->alloc_tag==NULL inside
__alloc_tagging_slab_alloc_hook() and dump the stack if that happens.
If there are no hits (which is probably what will happen) you can do
the same while checking for obj_exts==NULL. I suspect that condition
will hit multiple times and one of those will likely be the cause of
this warning. I'll look into this more tomorrow if the cause is not
found by then.

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