+ mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/huge_memory: add pmd folio to ds_queue in do_huge_zero_wp_pmd()
has been added to the -mm mm-new branch.  Its filename is
     mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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------------------------------------------------------
From: Wei Yang <richard.weiyang@gmail.com>
Subject: mm/huge_memory: add pmd folio to ds_queue in do_huge_zero_wp_pmd()
Date: Wed, 8 Oct 2025 09:54:52 +0000

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.

Link: https://lkml.kernel.org/r/20251008095453.18772-2-richard.weiyang@gmail.com
Fixes: 1ced09e0331f ("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>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/huge_memory.c~mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd
+++ a/mm/huge_memory.c
@@ -1317,6 +1317,7 @@ static void map_anon_folio_pmd(struct fo
 	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)
@@ -1357,7 +1358,6 @@ static vm_fault_t __do_huge_pmd_anonymou
 		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);
 	}
 
_

Patches currently in -mm which might be from richard.weiyang@gmail.com are

mm-compaction-check-the-range-to-pageblock_pfn_to_page-is-within-the-zone-first.patch
mm-compaction-fix-the-range-to-pageblock_pfn_to_page.patch
mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch
mm-khugepaged-unify-pmd-folio-installation-with-map_anon_folio_pmd.patch