Re: [PATCH 1/2] mm/compaction: skip folios containing hwpoisoned pages

[Huang, Ying]

Yuanhe Shu <xiangzao@xxxxxxxxxxxxxxxxx> writes:

> On 9/28/26 20:12, David Hildenbrand wrote:
>> On 9/28/26 12:58, Yuanhe Shu wrote:
>>> folio_mc_copy() does not close this hole: it only detects corruption
>>> at copy time and only where ARCH_HAS_COPY_MC is implemented (x86_64
>>> and PPC64; elsewhere copy_mc_highpage() degrades to a plain copy).
>>
>> Then they should implement it.
>
> Agreed, and nothing here replaces copy_mc.  Two things the check adds
> while that work is pending: on archs without copy_mc the plain copy
> does not fail, it consumes the poison - the same poison consumption
> commit 841a8bfcbad9 ("mm: prevent poison consumption when splitting
> THP") refused to risk on the split path, at your suggestion; and the
> refusal happens before the copy is attempted at all, while copy_mc
> recovers only during the read.  The check and copy_mc compose.
>

Is it good to implement the trick in copy_mc_user_highpage() and
copy_mc_highpage() if the macro copy_mc_to_kernel is undefined?

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Best Regards,
Huang, Ying