3 files changed, 33 insertions, 18 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2e872f92dbac..bf6f117fcf4d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1003,6 +1003,34 @@ static inline int page_mapped(struct page *page)
 }
 
 /*
+ * Return true only if the page has been allocated with
+ * ALLOC_NO_WATERMARKS and the low watermark was not
+ * met implying that the system is under some pressure.
+ */
+static inline bool page_is_pfmemalloc(struct page *page)
+{
+	/*
+	 * Page index cannot be this large so this must be
+	 * a pfmemalloc page.
+	 */
+	return page->index == -1UL;
+}
+
+/*
+ * Only to be called by the page allocator on a freshly allocated
+ * page.
+ */
+static inline void set_page_pfmemalloc(struct page *page)
+{
+	page->index = -1UL;
+}
+
+static inline void clear_page_pfmemalloc(struct page *page)
+{
+	page->index = 0;
+}
+
+/*
  * Different kinds of faults, as returned by handle_mm_fault().
  * Used to decide whether a process gets delivered SIGBUS or
  * just gets major/minor fault counters bumped up.
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 0038ac7466fd..15549578d559 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -63,15 +63,6 @@ struct page {
 		union {
 			pgoff_t index;		/* Our offset within mapping. */
 			void *freelist;		/* sl[aou]b first free object */
-			bool pfmemalloc;	/* If set by the page allocator,
-						 * ALLOC_NO_WATERMARKS was set
-						 * and the low watermark was not
-						 * met implying that the system
-						 * is under some pressure. The
-						 * caller should try ensure
-						 * this page is only used to
-						 * free other pages.
-						 */
 		};
 
 		union {
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 22b6d9ca1654..9b88536487e6 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1602,20 +1602,16 @@ static inline void __skb_fill_page_desc(struct sk_buff *skb, int i,
 	skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
 
 	/*
-	 * Propagate page->pfmemalloc to the skb if we can. The problem is
-	 * that not all callers have unique ownership of the page. If
-	 * pfmemalloc is set, we check the mapping as a mapping implies
-	 * page->index is set (index and pfmemalloc share space).
-	 * If it's a valid mapping, we cannot use page->pfmemalloc but we
-	 * do not lose pfmemalloc information as the pages would not be
-	 * allocated using __GFP_MEMALLOC.
+	 * Propagate page pfmemalloc to the skb if we can. The problem is
+	 * that not all callers have unique ownership of the page but rely
+	 * on page_is_pfmemalloc doing the right thing(tm).
 	 */
 	frag->page.p		  = page;
 	frag->page_offset	  = off;
 	skb_frag_size_set(frag, size);
 
 	page = compound_head(page);
-	if (page->pfmemalloc && !page->mapping)
+	if (page_is_pfmemalloc(page))
 		skb->pfmemalloc	= true;
 }
 
@@ -2263,7 +2259,7 @@ static inline struct page *dev_alloc_page(void)
 static inline void skb_propagate_pfmemalloc(struct page *page,
 					     struct sk_buff *skb)
 {
-	if (page && page->pfmemalloc)
+	if (page_is_pfmemalloc(page))
 		skb->pfmemalloc = true;
 }