Re: [PATCH] mm/page_alloc: Fix freeing of failed-split poisoned compound pages

[Boudewijn van der Heide <boudewijn@delta-utec.com>]

Thanks Jiaqi for the feedback, that is very helpful.
(and thanks Miaohe for connecting the issues.)

After going through the memory_failure(),
I can see it indeed puts the PG_HWPoison flag on the specific subpage pointer,
and therefore my fix won't work as-is.

> >
> > Yes, this is also a problematic scenario for Hugetlb HugePage. And Jiaqi works on
> > it now [1]. I think Jiaqi's patches might apply to THP scenario too. Add @Jiaqi to
> > verify this.
> 
> Yep, I think my work will also help solve the concern when
> try_to_split_thp_page() fails.

Your fix makes a lot of sense for hugetlb,
as it linearly scans through all the pages.
From my understanding, 
your fix also provides the perfect architecture for also checking THP,
though it doesn't yet cover the in-use THP case outlined.

For THP I would need to trace the failed-split paths more carefully,
to check where the equivalent path for THP would be. 

If there is work needed for THP, I'm happy to help.
Would you prefer I work on THP support as a separate follow-up patch,
after yours is merged,
or do you prefer to integrate it in your patch series?

> >
> > [1]: https://lore.kernel.org/all/20260112004923.888429-1-jiaqiyan@google.com/
> >
> > Thanks.
> > .

Thanks,
Boudewijn