HWPOISON: detect free buddy pages explicitly

Most free pages in the buddy system have no PG_buddy set. Introduce is_free_buddy_page() for detecting them reliably. CC: Nick Piggin <npiggin@suse.de> CC: Mel Gorman <mel@linux.vnet.ibm.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>

HWPOISON: detect free buddy pages explicitly
Most free pages in the buddy system have no PG_buddy set. Introduce is_free_buddy_page() for detecting them reliably. CC: Nick Piggin <npiggin@suse.de> CC: Mel Gorman <mel@linux.vnet.ibm.com> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andi Kleen <ak@linux.intel.com>
Wu Fengguang · Andi Kleen
1 parent 95d01fc664
Showing 3 changed files with 31 additions and 2 deletions Side-by-side Diff
mm/internal.h
mm/memory-failure.c
mm/page_alloc.c
@@ -50,6 +50,9 @@
  */
 extern void __free_pages_bootmem(struct page *page, unsigned int order);
 extern void prep_compound_page(struct page *page, unsigned long order);
+#ifdef CONFIG_MEMORY_FAILURE
+extern bool is_free_buddy_page(struct page *page);
+#endif
  
  
 /*
@@ -807,8 +807,13 @@
 	 */
 	if (!(flags & MF_COUNT_INCREASED) &&
 		!get_page_unless_zero(compound_head(p))) {
-		action_result(pfn, "free or high order kernel", IGNORED);
-		return PageBuddy(compound_head(p)) ? 0 : -EBUSY;
+		if (is_free_buddy_page(p)) {
+			action_result(pfn, "free buddy", DELAYED);
+			return 0;
+		} else {
+			action_result(pfn, "high order kernel", IGNORED);
+			return -EBUSY;
+		}
 	}
  
 	/*
@@ -5081,4 +5081,25 @@
 	spin_unlock_irqrestore(&zone->lock, flags);
 }
 #endif
+
+#ifdef CONFIG_MEMORY_FAILURE
+bool is_free_buddy_page(struct page *page)
+{
+	struct zone *zone = page_zone(page);
+	unsigned long pfn = page_to_pfn(page);
+	unsigned long flags;
+	int order;
+
+	spin_lock_irqsave(&zone->lock, flags);
+	for (order = 0; order < MAX_ORDER; order++) {
+		struct page *page_head = page - (pfn & ((1 << order) - 1));
+
+		if (PageBuddy(page_head) && page_order(page_head) >= order)
+			break;
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+
+	return order < MAX_ORDER;
+}
+#endif
...	...	@@ -50,6 +50,9 @@
50	50	*/
51	51	extern void __free_pages_bootmem(struct page *page, unsigned int order);
52	52	extern void prep_compound_page(struct page *page, unsigned long order);
	53	+#ifdef CONFIG_MEMORY_FAILURE
	54	+extern bool is_free_buddy_page(struct page *page);
	55	+#endif
53	56
54	57
55	58	/*
...	...	@@ -807,8 +807,13 @@
807	807	*/
808	808	if (!(flags & MF_COUNT_INCREASED) &&
809	809	!get_page_unless_zero(compound_head(p))) {
810		- action_result(pfn, "free or high order kernel", IGNORED);
811		- return PageBuddy(compound_head(p)) ? 0 : -EBUSY;
	810	+ if (is_free_buddy_page(p)) {
	811	+ action_result(pfn, "free buddy", DELAYED);
	812	+ return 0;
	813	+ } else {
	814	+ action_result(pfn, "high order kernel", IGNORED);
	815	+ return -EBUSY;
	816	+ }
812	817	}
813	818
814	819	/*
...	...	@@ -5081,4 +5081,25 @@
5081	5081	spin_unlock_irqrestore(&zone->lock, flags);
5082	5082	}
5083	5083	#endif
	5084	+
	5085	+#ifdef CONFIG_MEMORY_FAILURE
	5086	+bool is_free_buddy_page(struct page *page)
	5087	+{
	5088	+ struct zone *zone = page_zone(page);
	5089	+ unsigned long pfn = page_to_pfn(page);
	5090	+ unsigned long flags;
	5091	+ int order;
	5092	+
	5093	+ spin_lock_irqsave(&zone->lock, flags);
	5094	+ for (order = 0; order < MAX_ORDER; order++) {
	5095	+ struct page *page_head = page - (pfn & ((1 << order) - 1));
	5096	+
	5097	+ if (PageBuddy(page_head) && page_order(page_head) >= order)
	5098	+ break;
	5099	+ }
	5100	+ spin_unlock_irqrestore(&zone->lock, flags);
	5101	+
	5102	+ return order < MAX_ORDER;
	5103	+}
	5104	+#endif