+ mm-mprotect-always-skip-dma-pinned-folio-in-prot_numa_skip.patch added to mm-unstable branch

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

The patch titled
     Subject: mm: mprotect: always skip dma pinned folio in prot_numa_skip()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mprotect-always-skip-dma-pinned-folio-in-prot_numa_skip.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mprotect-always-skip-dma-pinned-folio-in-prot_numa_skip.patch

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

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------------------------------------------------------
From: Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: mm: mprotect: always skip dma pinned folio in prot_numa_skip()
Date: Thu, 23 Oct 2025 19:37:34 +0800

Patch series "mm: some optimizations for prot numa", v5.


This patch (of 4):

If the folio (even not CoW folio) is dma pinned, it can't be migrated due
to the elevated reference count.  So always skip a pinned folio to avoid
wasting cycles when folios are migrated.

Link: https://lkml.kernel.org/r/20251023113737.3572790-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20251023113737.3572790-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mprotect.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/mm/mprotect.c~mm-mprotect-always-skip-dma-pinned-folio-in-prot_numa_skip
+++ a/mm/mprotect.c
@@ -136,9 +136,12 @@ static bool prot_numa_skip(struct vm_are
 	if (folio_is_zone_device(folio) || folio_test_ksm(folio))
 		goto skip;
 
-	/* Also skip shared copy-on-write pages */
-	if (is_cow_mapping(vma->vm_flags) &&
-	    (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio)))
+	/* Also skip shared copy-on-write folios */
+	if (is_cow_mapping(vma->vm_flags) && folio_maybe_mapped_shared(folio))
+		goto skip;
+
+	/* Folios are pinned and can't be migrated */
+	if (folio_maybe_dma_pinned(folio))
 		goto skip;
 
 	/*
_

Patches currently in -mm which might be from wangkefeng.wang@huawei.com are

mm-mprotect-always-skip-dma-pinned-folio-in-prot_numa_skip.patch
mm-mprotect-avoid-unnecessary-struct-page-accessing-if-pte_protnone.patch
mm-mprotect-convert-to-folio_can_map_prot_numa.patch
mm-huge_memory-use-folio_can_map_prot_numa-for-pmd-folio.patch
mm-debug_vm_pgtable-add-debug_vm_pgtable_free_huge_page.patch
mm-page_alloc-add-__split_page.patch
mm-cma-add-__cma_release.patch
mm-page_alloc-add-alloc_contig_frozen_rangepages.patch
mm-cma-add-cma_alloc_frozen_compound.patch
mm-hugetlb-allocate-frozen-pages-in-alloc_gigantic_folio.patch