mm: add thp_head

This is like compound_head() but compiles away when CONFIG_TRANSPARENT_HUGEPAGE is not enabled. Signed-off-by: Matthew Wilcox (Oracle) <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: William Kucharski <[email protected]> Reviewed-by: Zi Yan <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]>
tadfisher · Aug 15, 2020 · 2be1d71 · 2be1d71
1 parent 6c35784
commit 2be1d71
Showing 1 changed file with 15 additions and 0 deletions.
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
@@ -259,6 +259,15 @@ static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
 		return NULL;
 }
 
+/**
+ * thp_head - Head page of a transparent huge page.
+ * @page: Any page (tail, head or regular) found in the page cache.
+ */
+static inline struct page *thp_head(struct page *page)
+{
+	return compound_head(page);
+}
+
 /**
  * thp_order - Order of a transparent huge page.
  * @page: Head page of a transparent huge page.
@@ -335,6 +344,12 @@ static inline struct list_head *page_deferred_list(struct page *page)
 #define HPAGE_PUD_MASK ({ BUILD_BUG(); 0; })
 #define HPAGE_PUD_SIZE ({ BUILD_BUG(); 0; })
 
+static inline struct page *thp_head(struct page *page)
+{
+	VM_BUG_ON_PGFLAGS(PageTail(page), page);
+	return page;
+}
+
 static inline unsigned int thp_order(struct page *page)
 {
 	VM_BUG_ON_PGFLAGS(PageTail(page), page);