mm/memcg: Convert mem_cgroup_uncharge() to take a folio

Convert all the callers to call page_folio().  Most of them were already
using a head page, but a few of them I can't prove were, so this may
actually fix a bug.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

include/linux/memcontrol.h

@@ -722,12 +722,19 @@ int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm,
 				  gfp_t gfp, swp_entry_t entry);
 void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry);
 
-void __mem_cgroup_uncharge(struct page *page);
+void __mem_cgroup_uncharge(struct folio *folio);
-static inline void mem_cgroup_uncharge(struct page *page)
+
+/**
+ * mem_cgroup_uncharge - Uncharge a folio.
+ * @folio: Folio to uncharge.
+ *
+ * Uncharge a folio previously charged with mem_cgroup_charge().
+ */
+static inline void mem_cgroup_uncharge(struct folio *folio)
 {
 	if (mem_cgroup_disabled())
 		return;
-	__mem_cgroup_uncharge(page);
+	__mem_cgroup_uncharge(folio);
 }
 
 void __mem_cgroup_uncharge_list(struct list_head *page_list);
@@ -1229,7 +1236,7 @@ static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry)
 {
 }
 
-static inline void mem_cgroup_uncharge(struct page *page)
+static inline void mem_cgroup_uncharge(struct folio *folio)
 {
 }
 

mm/filemap.c

@@ -940,7 +940,7 @@ unlock:
 	if (xas_error(&xas)) {
 		error = xas_error(&xas);
 		if (charged)
-			mem_cgroup_uncharge(page);
+			mem_cgroup_uncharge(page_folio(page));
 		goto error;
 	}
 

mm/khugepaged.c

@@ -1211,7 +1211,7 @@ out_up_write:
 	mmap_write_unlock(mm);
 out_nolock:
 	if (!IS_ERR_OR_NULL(*hpage))
-		mem_cgroup_uncharge(*hpage);
+		mem_cgroup_uncharge(page_folio(*hpage));
 	trace_mm_collapse_huge_page(mm, isolated, result);
 	return;
 }
@@ -1975,7 +1975,7 @@ xa_unlocked:
 out:
 	VM_BUG_ON(!list_empty(&pagelist));
 	if (!IS_ERR_OR_NULL(*hpage))
-		mem_cgroup_uncharge(*hpage);
+		mem_cgroup_uncharge(page_folio(*hpage));
 	/* TODO: tracepoints */
 }
 

mm/memcontrol.c

@@ -6858,22 +6858,16 @@ static void uncharge_folio(struct folio *folio, struct uncharge_gather *ug)
 	css_put(&memcg->css);
 }
 
-/**
+void __mem_cgroup_uncharge(struct folio *folio)
- * __mem_cgroup_uncharge - uncharge a page
- * @page: page to uncharge
- *
- * Uncharge a page previously charged with __mem_cgroup_charge().
- */
-void __mem_cgroup_uncharge(struct page *page)
 {
 	struct uncharge_gather ug;
 
-	/* Don't touch page->lru of any random page, pre-check: */
+	/* Don't touch folio->lru of any random page, pre-check: */
-	if (!page_memcg(page))
+	if (!folio_memcg(folio))
 		return;
 
 	uncharge_gather_clear(&ug);
-	uncharge_folio(page_folio(page), &ug);
+	uncharge_folio(folio, &ug);
 	uncharge_batch(&ug);
 }
 

mm/memory-failure.c

@@ -762,7 +762,7 @@ static int delete_from_lru_cache(struct page *p)
 		 * Poisoned page might never drop its ref count to 0 so we have
 		 * to uncharge it manually from its memcg.
 		 */
-		mem_cgroup_uncharge(p);
+		mem_cgroup_uncharge(page_folio(p));
 
 		/*
 		 * drop the page count elevated by isolate_lru_page()

mm/memremap.c

@@ -505,7 +505,7 @@ void free_devmap_managed_page(struct page *page)
 
 	__ClearPageWaiters(page);
 
-	mem_cgroup_uncharge(page);
+	mem_cgroup_uncharge(page_folio(page));
 
 	/*
 	 * When a device_private page is freed, the page->mapping field

mm/page_alloc.c

@@ -724,7 +724,7 @@ static inline void free_the_page(struct page *page, unsigned int order)
 
 void free_compound_page(struct page *page)
 {
-	mem_cgroup_uncharge(page);
+	mem_cgroup_uncharge(page_folio(page));
 	free_the_page(page, compound_order(page));
 }
 

mm/swap.c

@@ -94,7 +94,7 @@ static void __page_cache_release(struct page *page)
 static void __put_single_page(struct page *page)
 {
 	__page_cache_release(page);
-	mem_cgroup_uncharge(page);
+	mem_cgroup_uncharge(page_folio(page));
 	free_unref_page(page, 0);
 }