hugetlb: convert alloc_buddy_hugetlb_folio to use a folio

While this function returned a folio, it was still using __alloc_pages() and __free_pages(). Use __folio_alloc() and put_folio() instead. This actually removes a call to compound_head(), but more importantly, it prepares us for the move to memdescs. Link: https://lkml.kernel.org/r/20240402200656.913841-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Muchun Song <muchun.song@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Matthew Wilcox (Oracle)

mm/hugetlb.c

@@ -2177,13 +2177,13 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
 nodemask_t *node_alloc_noretry)
 {
 int order = huge_page_order(h);
-struct page *page;
+struct folio *folio;
 bool alloc_try_hard = true;
 bool retry = true;
 
 /*
- * By default we always try hard to allocate the page with
- * __GFP_RETRY_MAYFAIL flag. However, if we are allocating pages in
+ * By default we always try hard to allocate the folio with
+ * __GFP_RETRY_MAYFAIL flag. However, if we are allocating folios in
  * a loop (to adjust global huge page counts) and previous allocation
  * failed, do not continue to try hard on the same node. Use the
  * node_alloc_noretry bitmap to manage this state information.
@@ -2196,43 +2196,42 @@ static struct folio *alloc_buddy_hugetlb_folio(struct hstate *h,
 if (nid == NUMA_NO_NODE)
 nid = numa_mem_id();
 retry:
-page = __alloc_pages(gfp_mask, order, nid, nmask);
+folio = __folio_alloc(gfp_mask, order, nid, nmask);
 
-/* Freeze head page */
-if (page && !page_ref_freeze(page, 1)) {
-__free_pages(page, order);
+if (folio && !folio_ref_freeze(folio, 1)) {
+folio_put(folio);
 if (retry) {/* retry once */
 retry = false;
 goto retry;
 }
 /* WOW! twice in a row. */
-pr_warn("HugeTLB head page unexpected inflated ref count\n");
-page = NULL;
+pr_warn("HugeTLB unexpected inflated folio ref count\n");
+folio = NULL;
 }
 
 /*
- * If we did not specify __GFP_RETRY_MAYFAIL, but still got a page this
- * indicates an overall state change. Clear bit so that we resume
- * normal 'try hard' allocations.
+ * If we did not specify __GFP_RETRY_MAYFAIL, but still got a
+ * folio this indicates an overall state change. Clear bit so
+ * that we resume normal 'try hard' allocations.
  */
-if (node_alloc_noretry && page && !alloc_try_hard)
+if (node_alloc_noretry && folio && !alloc_try_hard)
 node_clear(nid, *node_alloc_noretry);
 
 /*
- * If we tried hard to get a page but failed, set bit so that
+ * If we tried hard to get a folio but failed, set bit so that
  * subsequent attempts will not try as hard until there is an
  * overall state change.
  */
-if (node_alloc_noretry && !page && alloc_try_hard)
+if (node_alloc_noretry && !folio && alloc_try_hard)
 node_set(nid, *node_alloc_noretry);
 
-if (!page) {
+if (!folio) {
 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 return NULL;
 }
 
 __count_vm_event(HTLB_BUDDY_PGALLOC);
-return page_folio(page);
+return folio;
 }
 
 static struct folio *__alloc_fresh_hugetlb_folio(struct hstate *h,