mm/mempolicy: convert queue_pages_hugetlb() to queue_folios_hugetlb()

This change is in preparation for the conversion of queue_pages_required()
to queue_folio_required() and migrate_page_add() to migrate_folio_add().

Link: https://lkml.kernel.org/r/20230130201833.27042-5-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: "Yin, Fengwei" <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index b0805bb87655f5d310b38dc76e424048b1cc3770..66839249350005fdf72e2d851d1268699f0b2225 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -558,7 +558,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
        return addr != end ? -EIO : 0;
 }
 
-static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
+static int queue_folios_hugetlb(pte_t *pte, unsigned long hmask,
                               unsigned long addr, unsigned long end,
                               struct mm_walk *walk)
 {
@@ -566,7 +566,7 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
 #ifdef CONFIG_HUGETLB_PAGE
        struct queue_pages *qp = walk->private;
        unsigned long flags = (qp->flags & MPOL_MF_VALID);
-       struct page *page;
+       struct folio *folio;
        spinlock_t *ptl;
        pte_t entry;
 
@@ -574,13 +574,13 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
        entry = huge_ptep_get(pte);
        if (!pte_present(entry))
                goto unlock;
-       page = pte_page(entry);
-       if (!queue_pages_required(page, qp))
+       folio = pfn_folio(pte_pfn(entry));
+       if (!queue_pages_required(&folio->page, qp))
                goto unlock;
 
        if (flags == MPOL_MF_STRICT) {
                /*
-                * STRICT alone means only detecting misplaced page and no
+                * STRICT alone means only detecting misplaced folio and no
                 * need to further check other vma.
                 */
                ret = -EIO;
@@ -591,21 +591,28 @@ static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
                /*
                 * Must be STRICT with MOVE*, otherwise .test_walk() have
                 * stopped walking current vma.
-                * Detecting misplaced page but allow migrating pages which
+                * Detecting misplaced folio but allow migrating folios which
                 * have been queued.
                 */
                ret = 1;
                goto unlock;
        }
 
-       /* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
+       /*
+        * With MPOL_MF_MOVE, we try to migrate only unshared folios. If it
+        * is shared it is likely not worth migrating.
+        *
+        * To check if the folio is shared, ideally we want to make sure
+        * every page is mapped to the same process. Doing that is very
+        * expensive, so check the estimated mapcount of the folio instead.
+        */
        if (flags & (MPOL_MF_MOVE_ALL) ||
-           (flags & MPOL_MF_MOVE && page_mapcount(page) == 1 &&
+           (flags & MPOL_MF_MOVE && folio_estimated_sharers(folio) == 1 &&
             !hugetlb_pmd_shared(pte))) {
-               if (isolate_hugetlb(page_folio(page), qp->pagelist) &&
+               if (isolate_hugetlb(folio, qp->pagelist) &&
                        (flags & MPOL_MF_STRICT))
                        /*
-                        * Failed to isolate page but allow migrating pages
+                        * Failed to isolate folio but allow migrating pages
                         * which have been queued.
                         */
                        ret = 1;
@@ -703,7 +710,7 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
 }
 
 static const struct mm_walk_ops queue_pages_walk_ops = {
-       .hugetlb_entry          = queue_pages_hugetlb,
+       .hugetlb_entry          = queue_folios_hugetlb,
        .pmd_entry              = queue_folios_pte_range,
        .test_walk              = queue_pages_test_walk,
 };