Commit 2a1351cd authored Oct 08, 2025 by Wei Yang Committed by Andrew Morton Nov 24, 2025

mm/huge_memory: add pmd folio to ds_queue in do_huge_zero_wp_pmd()

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 1ced09e0 ("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.

Link: https://lkml.kernel.org/r/20251008095453.18772-2-richard.weiyang@gmail.com


Fixes: 1ced09e0 ("mm: allocate THP on hugezeropage wp-fault")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent c3228747

mm/huge_memory.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1233,6 +1233,7 @@ static void map_anon_folio_pmd(struct folio folio, pmd_t pmd,
		count_vm_event(THP_FAULT_ALLOC);
		count_mthp_stat(HPAGE_PMD_ORDER, MTHP_STAT_ANON_FAULT_ALLOC);
		count_memcg_event_mm(vma->vm_mm, THP_FAULT_ALLOC);
		deferred_split_folio(folio, false);
		}

		static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
		@@ -1273,7 +1274,6 @@ static vm_fault_t __do_huge_pmd_anonymous_page(struct vm_fault *vmf)
		pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
		map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
		mm_inc_nr_ptes(vma->vm_mm);
		deferred_split_folio(folio, false);
		spin_unlock(vmf->ptl);
		}