mm/hugetlb: rename folio_putback_active_hugetlb() to folio_putback_hugetlb()

Now that folio_putback_hugetlb() is only called on folios that were
previously isolated through folio_isolate_hugetlb(), let's rename it to
match folio_putback_lru().

Add some kernel doc to clarify how this function is supposed to be used.

Link: https://lkml.kernel.org/r/20250113131611.2554758-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
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

@@ -157,7 +157,7 @@ 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);
-void folio_putback_active_hugetlb(struct folio *folio);
+void folio_putback_hugetlb(struct folio *folio);
 void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int reason);
 void hugetlb_fix_reserve_counts(struct inode *inode);
 extern struct mutex *hugetlb_fault_mutex_table;
@@ -430,7 +430,7 @@ static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 	return 0;
 }
 
-static inline void folio_putback_active_hugetlb(struct folio *folio)
+static inline void folio_putback_hugetlb(struct folio *folio)
 {
 }
 

mm/hugetlb.c

@@ -7434,7 +7434,7 @@ __weak unsigned long hugetlb_mask_last_page(struct hstate *h)
  * 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.
+ * using folio_putback_hugetlb() to undo the isolation.
  *
  * Return: True if isolation worked, otherwise False.
  */
@@ -7486,7 +7486,18 @@ int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
 	return ret;
 }
 
-void folio_putback_active_hugetlb(struct folio *folio)
+/**
+ * folio_putback_hugetlb - unisolate a hugetlb folio
+ * @folio: the isolated hugetlb folio
+ *
+ * Putback/un-isolate the hugetlb folio that was previous isolated using
+ * folio_isolate_hugetlb(): marking it non-isolated/migratable and putting it
+ * back onto the active list.
+ *
+ * Will drop the additional folio reference obtained through
+ * folio_isolate_hugetlb().
+ */
+void folio_putback_hugetlb(struct folio *folio)
 {
 	spin_lock_irq(&hugetlb_lock);
 	folio_set_hugetlb_migratable(folio);

mm/migrate.c

@@ -137,7 +137,7 @@ void putback_movable_pages(struct list_head *l)
 
 	list_for_each_entry_safe(folio, folio2, l, lru) {
 		if (unlikely(folio_test_hugetlb(folio))) {
-			folio_putback_active_hugetlb(folio);
+			folio_putback_hugetlb(folio);
 			continue;
 		}
 		list_del(&folio->lru);
@@ -1451,7 +1451,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 
 	if (folio_ref_count(src) == 1) {
 		/* page was freed from under us. So we are done. */
-		folio_putback_active_hugetlb(src);
+		folio_putback_hugetlb(src);
 		return MIGRATEPAGE_SUCCESS;
 	}
 
@@ -1534,7 +1534,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 	folio_unlock(src);
 out:
 	if (rc == MIGRATEPAGE_SUCCESS)
-		folio_putback_active_hugetlb(src);
+		folio_putback_hugetlb(src);
 	else if (rc != -EAGAIN)
 		list_move_tail(&src->lru, ret);