X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=include%2Flinux%2Fmm.h;h=3c2f6b452586f233dfdbe1f0ce1580733430f2ee;hb=c8070b78751955e59b42457b974bea4a4fe00187;hp=27ce77080c79c7a026e641e491246fcf6f7e26c0;hpb=ed9a65e575cc3c52a7f130d824671fe48a72da0c;p=linux-block.git

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 27ce77080c79..3c2f6b452586 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1910,6 +1910,28 @@ static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
 	return page_maybe_dma_pinned(page);
 }
 
+/**
+ * is_zero_page - Query if a page is a zero page
+ * @page: The page to query
+ *
+ * This returns true if @page is one of the permanent zero pages.
+ */
+static inline bool is_zero_page(const struct page *page)
+{
+	return is_zero_pfn(page_to_pfn(page));
+}
+
+/**
+ * is_zero_folio - Query if a folio is a zero page
+ * @folio: The folio to query
+ *
+ * This returns true if @folio is one of the permanent zero pages.
+ */
+static inline bool is_zero_folio(const struct folio *folio)
+{
+	return is_zero_page(&folio->page);
+}
+
 /* MIGRATE_CMA and ZONE_MOVABLE do not allow pin pages */
 #ifdef CONFIG_MIGRATION
 static inline bool is_longterm_pinnable_page(struct page *page)
@@ -1920,8 +1942,8 @@ static inline bool is_longterm_pinnable_page(struct page *page)
 	if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
 		return false;
 #endif
-	/* The zero page may always be pinned */
-	if (is_zero_pfn(page_to_pfn(page)))
+	/* The zero page can be "pinned" but gets special handling. */
+	if (is_zero_page(page))
 		return true;
 
 	/* Coherent device memory must always allow eviction. */