mm/hugetlb: rename isolate_hugetlb() to folio_isolate_hugetlb()

Let's make the function name match "folio_isolate_lru()", and add some
kernel doc.

Link: https://lkml.kernel.org/r/20250113131611.2554758-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: davidhildenbrand

include/linux/hugetlb.h

@@ -153,7 +153,7 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to,
 						vm_flags_t vm_flags);
 long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
 						long freed);
-bool isolate_hugetlb(struct folio *folio, struct list_head *list);
+bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list);
 int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison);
 int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 				bool *migratable_cleared);
@@ -414,7 +414,7 @@ static inline pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr,
 	return NULL;
 }
 
-static inline bool isolate_hugetlb(struct folio *folio, struct list_head *list)
+static inline bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list)
 {
 	return false;
 }

mm/gup.c

@@ -2344,7 +2344,7 @@ static unsigned long collect_longterm_unpinnable_folios(
 			continue;
 
 		if (folio_test_hugetlb(folio)) {
-			isolate_hugetlb(folio, movable_folio_list);
+			folio_isolate_hugetlb(folio, movable_folio_list);
 			continue;
 		}
 

mm/hugetlb.c

@@ -2812,7 +2812,7 @@ static int alloc_and_dissolve_hugetlb_folio(struct hstate *h,
 		 * Fail with -EBUSY if not possible.
 		 */
 		spin_unlock_irq(&hugetlb_lock);
-		isolated = isolate_hugetlb(old_folio, list);
+		isolated = folio_isolate_hugetlb(old_folio, list);
 		ret = isolated ? 0 : -EBUSY;
 		spin_lock_irq(&hugetlb_lock);
 		goto free_new;
@@ -2897,7 +2897,7 @@ int isolate_or_dissolve_huge_page(struct page *page, struct list_head *list)
 	if (hstate_is_gigantic(h))
 		return -ENOMEM;
 
-	if (folio_ref_count(folio) && isolate_hugetlb(folio, list))
+	if (folio_ref_count(folio) && folio_isolate_hugetlb(folio, list))
 		ret = 0;
 	else if (!folio_ref_count(folio))
 		ret = alloc_and_dissolve_hugetlb_folio(h, folio, list);
@@ -7421,7 +7421,24 @@ __weak unsigned long hugetlb_mask_last_page(struct hstate *h)
 
 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
 
-bool isolate_hugetlb(struct folio *folio, struct list_head *list)
+/**
+ * folio_isolate_hugetlb - try to isolate an allocated hugetlb folio
+ * @folio: the folio to isolate
+ * @list: the list to add the folio to on success
+ *
+ * Isolate an allocated (refcount > 0) hugetlb folio, marking it as
+ * isolated/non-migratable, and moving it from the active list to the
+ * given list.
+ *
+ * Isolation will fail if @folio is not an allocated hugetlb folio, or if
+ * it is already isolated/non-migratable.
+ *
+ * On success, an additional folio reference is taken that must be dropped
+ * using folio_putback_active_hugetlb() to undo the isolation.
+ *
+ * Return: True if isolation worked, otherwise False.
+ */
+bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list)
 {
 	bool ret = true;
 

mm/mempolicy.c

@@ -647,7 +647,7 @@ static int queue_folios_hugetlb(pte_t *pte, unsigned long hmask,
 	 */
 	if ((flags & MPOL_MF_MOVE_ALL) ||
 	    (!folio_likely_mapped_shared(folio) && !hugetlb_pmd_shared(pte)))
-		if (!isolate_hugetlb(folio, qp->pagelist))
+		if (!folio_isolate_hugetlb(folio, qp->pagelist))
 			qp->nr_failed++;
 unlock:
 	spin_unlock(ptl);

mm/migrate.c

@@ -128,7 +128,7 @@ static void putback_movable_folio(struct folio *folio)
  *
  * This function shall be used whenever the isolated pageset has been
  * built from lru, balloon, hugetlbfs page. See isolate_migratepages_range()
- * and isolate_hugetlb().
+ * and folio_isolate_hugetlb().
  */
 void putback_movable_pages(struct list_head *l)
 {
@@ -169,7 +169,7 @@ bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
 	bool isolated, lru;
 
 	if (folio_test_hugetlb(folio))
-		return isolate_hugetlb(folio, list);
+		return folio_isolate_hugetlb(folio, list);
 
 	lru = !__folio_test_movable(folio);
 	if (lru)
@@ -2200,7 +2200,7 @@ static int __add_folio_for_migration(struct folio *folio, int node,
 		return -EACCES;
 
 	if (folio_test_hugetlb(folio)) {
-		if (isolate_hugetlb(folio, pagelist))
+		if (folio_isolate_hugetlb(folio, pagelist))
 			return 1;
 	} else if (folio_isolate_lru(folio)) {
 		list_add_tail(&folio->lru, pagelist);