mm: huge_memory: use folio_can_map_prot_numa() for pmd folio

The folio_can_map_prot_numa() checks whether the folio can map prot numa,
which skips unsuitable folio, i.e.  zone device, shared folios (KSM, CoW),
non-movable dma pinned, dirty file folio and folios that already have the
expected node affinity.  Although the ksm only applies to small folios, an
extra test was added for large folios, but the other policies should be
applied to pmd folio, which helps to avoid unnecessary pmd change and
folio migration attempts.

Link: https://lkml.kernel.org/r/20251023113737.3572790-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
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: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7ad9d2ba50d4aeef4f360030f6ac3bd9ca9a291f..ffdf2ccf826916bd00c62b7dc71bc7f49bc62b99 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2396,8 +2396,7 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 #endif
 
        if (prot_numa) {
-               struct folio *folio;
-               bool toptier;
+
                /*
                 * Avoid trapping faults against the zero page. The read-only
                 * data is likely to be read-cached on the local CPU and
@@ -2409,19 +2408,9 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                if (pmd_protnone(*pmd))
                        goto unlock;
 
-               folio = pmd_folio(*pmd);
-               toptier = node_is_toptier(folio_nid(folio));
-               /*
-                * Skip scanning top tier node if normal numa
-                * balancing is disabled
-                */
-               if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) &&
-                   toptier)
+               if (!folio_can_map_prot_numa(pmd_folio(*pmd), vma,
+                                            vma_is_single_threaded_private(vma)))
                        goto unlock;
-
-               if (folio_use_access_time(folio))
-                       folio_xchg_access_time(folio,
-                                              jiffies_to_msecs(jiffies));
        }
        /*
         * In case prot_numa, we are under mmap_read_lock(mm). It's critical