mm/mempolicy: convert migrate_page_add() to migrate_folio_add()

[ Upstream commit 4a64981dfee9119aa2c1f243b48f34cbbd67779c ]

Replace migrate_page_add() with migrate_folio_add().  migrate_folio_add()
does the same a migrate_page_add() but takes in a folio instead of a page.
This removes a couple of calls to compound_head().

Link: https://lkml.kernel.org/r/20230130201833.27042-7-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 24526268f4e3 ("mm: mempolicy: keep VMA walk if both MPOL_MF_STRICT and MPOL_MF_MOVE are specified")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 2ae6c8f..158b0bc 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -414,7 +414,7 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
        },
 };
 
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
                                unsigned long flags);
 
 struct queue_pages {
@@ -476,7 +476,7 @@ static int queue_folios_pmd(pmd_t *pmd, spinlock_t *ptl, unsigned long addr,
        /* go to folio migration */
        if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
                if (!vma_migratable(walk->vma) ||
-                   migrate_page_add(&folio->page, qp->pagelist, flags)) {
+                   migrate_folio_add(folio, qp->pagelist, flags)) {
                        ret = 1;
                        goto unlock;
                }
@@ -544,7 +544,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
                         * temporary off LRU pages in the range.  Still
                         * need migrate other LRU pages.
                         */
-                       if (migrate_page_add(&folio->page, qp->pagelist, flags))
+                       if (migrate_folio_add(folio, qp->pagelist, flags))
                                has_unmovable = true;
                } else
                        break;
@@ -1012,27 +1012,28 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
 }
 
 #ifdef CONFIG_MIGRATION
-/*
- * page migration, thp tail pages can be passed.
- */
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
                                unsigned long flags)
 {
-       struct page *head = compound_head(page);
        /*
-        * Avoid migrating a page that is shared with others.
+        * 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) || page_mapcount(head) == 1) {
-               if (!isolate_lru_page(head)) {
-                       list_add_tail(&head->lru, pagelist);
-                       mod_node_page_state(page_pgdat(head),
-                               NR_ISOLATED_ANON + page_is_file_lru(head),
-                               thp_nr_pages(head));
+       if ((flags & MPOL_MF_MOVE_ALL) || folio_estimated_sharers(folio) == 1) {
+               if (!folio_isolate_lru(folio)) {
+                       list_add_tail(&folio->lru, foliolist);
+                       node_stat_mod_folio(folio,
+                               NR_ISOLATED_ANON + folio_is_file_lru(folio),
+                               folio_nr_pages(folio));
                } else if (flags & MPOL_MF_STRICT) {
                        /*
-                        * Non-movable page may reach here.  And, there may be
-                        * temporary off LRU pages or non-LRU movable pages.
-                        * Treat them as unmovable pages since they can't be
+                        * Non-movable folio may reach here.  And, there may be
+                        * temporary off LRU folios or non-LRU movable folios.
+                        * Treat them as unmovable folios since they can't be
                         * isolated, so they can't be moved at the moment.  It
                         * should return -EIO for this case too.
                         */
@@ -1224,7 +1225,7 @@ static struct page *new_page(struct page *page, unsigned long start)
 }
 #else
 
-static int migrate_page_add(struct page *page, struct list_head *pagelist,
+static int migrate_folio_add(struct folio *folio, struct list_head *foliolist,
                                unsigned long flags)
 {
        return -EIO;