Re: [Patch v2] mm/huge_memory: add pmd folio to ds_queue in do_huge_zero_wp_pmd()

[Wei Yang <richard.weiyang@gmail.com>]

On Thu, Oct 02, 2025 at 01:38:25AM +0000, Wei Yang wrote:
>We add pmd folio into ds_queue on the first page fault in
>__do_huge_pmd_anonymous_page(), so that we can split it in case of
>memory pressure. This should be the same for a pmd folio during wp
>page fault.
>
>Commit 1ced09e0331f ("mm: allocate THP on hugezeropage wp-fault") miss
>to add it to ds_queue, which means system may not reclaim enough memory
>in case of memory pressure even the pmd folio is under used.
>
>Move deferred_split_folio() into map_anon_folio_pmd() to make the pmd
>folio installation consistent.
>

Since we move deferred_split_folio() into map_anon_folio_pmd(), I am thinking
about whether we can consolidate the process in collapse_huge_page().

Use map_anon_folio_pmd() in collapse_huge_page(), but skip those statistic
adjustment.

>Fixes: 1ced09e0331f ("mm: allocate THP on hugezeropage wp-fault")
>Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>Cc: David Hildenbrand <david@redhat.com>
>Cc: Lance Yang <lance.yang@linux.dev>
>Cc: Dev Jain <dev.jain@arm.com>
>Cc: <stable@vger.kernel.org>
>

-- 
Wei Yang
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