mm: Make large folios depend on THP

Matthew Wilcox (Oracle) · Matthew Wilcox (Oracle) · commit 421f1ab48452 · 2022-03-21T13:01:36.000-04:00
Some parts of the VM still depend on THP to handle large folios
correctly.  Until those are fixed, prevent creating large folios
if THP are disabled.

Signed-off-by: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
@@ -306,9 +306,14 @@ static inline void mapping_set_large_folios(struct address_space *mapping)
 	__set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
 }
 
+/*
+ * Large folio support currently depends on THP.  These dependencies are
+ * being worked on but are not yet fixed.
+ */
 static inline bool mapping_large_folio_support(struct address_space *mapping)
 {
-	return test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
+	return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
+		test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);
 }
 
 static inline int filemap_nr_thps(struct address_space *mapping)

Original file line number	Diff line number	Diff line change
`@@ -306,9 +306,14 @@ static inline void mapping_set_large_folios(struct address_space *mapping)`
`306`	`306`	`__set_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);`
`307`	`307`	`}`
`308`	`308`
	`309`	`+/*`
	`310`	`+ * Large folio support currently depends on THP. These dependencies are`
	`311`	`+ * being worked on but are not yet fixed.`
	`312`	`+ */`
`309`	`313`	`static inline bool mapping_large_folio_support(struct address_space *mapping)`
`310`	`314`	`{`
`311`		`- return test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);`
	`315`	`+ return IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&`
	`316`	`+ test_bit(AS_LARGE_FOLIO_SUPPORT, &mapping->flags);`
`312`	`317`	`}`
`313`	`318`
`314`	`319`	`static inline int filemap_nr_thps(struct address_space *mapping)`