mm: add thp_order

commit 6ffbb45826f5d9ae09aa60cd88594b7816c96190 upstream

This function returns the order of a transparent huge page.  It compiles
to 0 if CONFIG_TRANSPARENT_HUGEPAGE is disabled.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: http://lkml.kernel.org/r/20200629151959.15779-4-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 93d5cf0bc7168fca9aca2179e2e94e3aafd42c43..d8b86fd3911345870830407c49d06c77a59b2b90 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -231,6 +231,19 @@ static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
        else
                return NULL;
 }
+
+/**
+ * thp_order - Order of a transparent huge page.
+ * @page: Head page of a transparent huge page.
+ */
+static inline unsigned int thp_order(struct page *page)
+{
+       VM_BUG_ON_PGFLAGS(PageTail(page), page);
+       if (PageHead(page))
+               return HPAGE_PMD_ORDER;
+       return 0;
+}
+
 static inline int hpage_nr_pages(struct page *page)
 {
        if (unlikely(PageTransHuge(page)))
@@ -290,6 +303,12 @@ 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 unsigned int thp_order(struct page *page)
+{
+       VM_BUG_ON_PGFLAGS(PageTail(page), page);
+       return 0;
+}
+
 #define hpage_nr_pages(x) 1
 
 static inline bool __transparent_hugepage_enabled(struct vm_area_struct *vma)