On 2025/1/14 14:00, Barry Song wrote:

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               if (!pvmw.pte) {
+                     lazyfree = folio_test_anon(folio) && !folio_test_swapbacked(folio);

You've checked lazyfree here, so can we remove the duplicate check in
unmap_huge_pmd_locked()? Then the code should be:

                 if (lazyfree && unmap_huge_pmd_locked(...))
                         goto walk_done;

right. it seems unmap_huge_pmd_locked() only handles lazyfree pmd-mapped
thp. so i guess the code could be:

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index aea49f7125f1..c4c3a7896de4 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c

@@ -3131,11 +3131,10 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
         VM_WARN_ON_FOLIO(!folio_test_pmd_mappable(folio), folio);
         VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
         VM_WARN_ON_ONCE(!IS_ALIGNED(addr, HPAGE_PMD_SIZE));
+       VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
+       VM_WARN_ON_FOLIO(folio_test_swapbacked(folio), folio);

-       if (folio_test_anon(folio) && !folio_test_swapbacked(folio))
-               return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio);
-
-       return false;
+       return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio);
  }

  static void remap_page(struct folio *folio, unsigned long nr, int flags)

diff --git a/mm/rmap.c b/mm/rmap.c
index 02c4e4b2cd7b..72907eb1b8fe 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c

@@ -1671,7 +1671,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
         DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
         pte_t pteval;
         struct page *subpage;
-       bool anon_exclusive, lazyfree, ret = true;
+       bool anon_exclusive, ret = true;
         struct mmu_notifier_range range;
         enum ttu_flags flags = (enum ttu_flags)(long)arg;
         int nr_pages = 1;

@@ -1724,18 +1724,16 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
                 }

                 if (!pvmw.pte) {
-                       lazyfree = folio_test_anon(folio) && !folio_test_swapbacked(folio);
-
-                       if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd,
-                                                 folio))
-                               goto walk_done;
-                       /*
-                        * unmap_huge_pmd_locked has either already marked
-                        * the folio as swap-backed or decided to retain it
-                        * due to GUP or speculative references.
-                        */
-                       if (lazyfree)
+                       if (folio_test_anon(folio) && !folio_test_swapbacked(folio)) {
+                               if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd, folio))
+                                       goto walk_done;
+                               /*
+                                * unmap_huge_pmd_locked has either already marked
+                                * the folio as swap-backed or decided to retain it
+                                * due to GUP or speculative references.
+                                */
                                 goto walk_abort;
+                       }

                         if (flags & TTU_SPLIT_HUGE_PMD) {
                                 /*

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                       if (unmap_huge_pmd_locked(vma, pvmw.address, pvmw.pmd,
                                                 folio))
                               goto walk_done;
+                     /*
+                      * unmap_huge_pmd_locked has either already marked
+                      * the folio as swap-backed or decided to retain it
+                      * due to GUP or speculative references.
+                      */
+                     if (lazyfree)
+                             goto walk_abort;

                       if (flags & TTU_SPLIT_HUGE_PMD) {
                               /*

The final diff is as follows.
Baolin, do you have any additional comments before I send out v3?

No other comments. Look good to me.