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

[Miaohe Lin]

On 2026/1/24 12:42, Jiaqi Yan wrote:
> On Fri, Jan 16, 2026 at 6:12 AM Boudewijn van der Heide
> <boudewijn@xxxxxxxxxxxxxx> wrote:
>>
>> 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.
> 
> Oh, sorry I went ahead myself and assumed the split-failed folio would
> eventually be released to the buddy allocator at some point when
> userspace processes who owns/maps this THP are killed or exited.
> 
> Zi and Miaohe, am I right about this? or do we need explicitly handle
> in-use and split-failed THP?

IMHO, it's enough to handle poisoned sub-pages when in-use or split-failed THP
eventually be released to the buddy.

Thanks.
.