mm/damon/vaddr: consistently use only pmd_entry for damos_migrate

For page table walks, it is usual [1] to have only one pmd entry function.
The vaddr.c code for DAMOS_MIGRATE_{HOT,COLD} is not following the
pattern.  Instead, it uses both pmd and pte entry functions without a
special reason.  Refactor it to use only the pmd entry function, to make
the code under mm/ more consistent.

Link: https://lkml.kernel.org/r/20251112154114.66053-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Suggested-by: David Hildenbrand <david@kernel.org>
Cc: Bill Wendling <morbo@google.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Justin Stitt <justinstitt@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index b9f0c9e3f68420e4829c8833d0fc2241201ddbe5..2750c88e722528fac3e6a256fda124557b62bc03 100644 (file)
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -697,7 +697,6 @@ isolate:
        list_add(&folio->lru, &migration_lists[i]);
 }
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
                unsigned long next, struct mm_walk *walk)
 {
@@ -707,58 +706,49 @@ static int damos_va_migrate_pmd_entry(pmd_t *pmd, unsigned long addr,
        struct damos_migrate_dests *dests = &s->migrate_dests;
        struct folio *folio;
        spinlock_t *ptl;
-       pmd_t pmde;
-
-       ptl = pmd_lock(walk->mm, pmd);
-       pmde = pmdp_get(pmd);
-
-       if (!pmd_present(pmde) || !pmd_trans_huge(pmde))
-               goto unlock;
-
-       /* Tell page walk code to not split the PMD */
-       walk->action = ACTION_CONTINUE;
-
-       folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
-       if (!folio)
-               goto unlock;
-
-       if (damos_va_filter_out(s, folio, walk->vma, addr, NULL, pmd))
-               goto unlock;
-
-       damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
-               migration_lists);
-
-unlock:
-       spin_unlock(ptl);
-       return 0;
-}
-#else
-#define damos_va_migrate_pmd_entry NULL
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+       pte_t *start_pte, *pte, ptent;
+       int nr;
 
-static int damos_va_migrate_pte_entry(pte_t *pte, unsigned long addr,
-               unsigned long next, struct mm_walk *walk)
-{
-       struct damos_va_migrate_private *priv = walk->private;
-       struct list_head *migration_lists = priv->migration_lists;
-       struct damos *s = priv->scheme;
-       struct damos_migrate_dests *dests = &s->migrate_dests;
-       struct folio *folio;
-       pte_t ptent;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+       ptl = pmd_trans_huge_lock(pmd, walk->vma);
+       if (ptl) {
+               pmd_t pmde = pmdp_get(pmd);
 
-       ptent = ptep_get(pte);
-       if (pte_none(ptent) || !pte_present(ptent))
+               if (!pmd_present(pmde))
+                       goto huge_out;
+               folio = vm_normal_folio_pmd(walk->vma, addr, pmde);
+               if (!folio)
+                       goto huge_out;
+               if (damos_va_filter_out(s, folio, walk->vma, addr, NULL, pmd))
+                       goto huge_out;
+               damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
+                               migration_lists);
+huge_out:
+               spin_unlock(ptl);
                return 0;
+       }
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
-       folio = vm_normal_folio(walk->vma, addr, ptent);
-       if (!folio)
+       start_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+       if (!pte)
                return 0;
 
-       if (damos_va_filter_out(s, folio, walk->vma, addr, pte, NULL))
-               return 0;
+       for (; addr < next; pte += nr, addr += nr * PAGE_SIZE) {
+               nr = 1;
+               ptent = ptep_get(pte);
 
-       damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
-               migration_lists);
+               if (pte_none(ptent) || !pte_present(ptent))
+                       continue;
+               folio = vm_normal_folio(walk->vma, addr, ptent);
+               if (!folio)
+                       continue;
+               if (damos_va_filter_out(s, folio, walk->vma, addr, pte, NULL))
+                       return 0;
+               damos_va_migrate_dests_add(folio, walk->vma, addr, dests,
+                               migration_lists);
+               nr = folio_nr_pages(folio);
+       }
+       pte_unmap_unlock(start_pte, ptl);
        return 0;
 }
 
@@ -824,7 +814,7 @@ static unsigned long damos_va_migrate(struct damon_target *target,
        struct damos_migrate_dests *dests = &s->migrate_dests;
        struct mm_walk_ops walk_ops = {
                .pmd_entry = damos_va_migrate_pmd_entry,
-               .pte_entry = damos_va_migrate_pte_entry,
+               .pte_entry = NULL,
                .walk_lock = PGWALK_RDLOCK,
        };