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>

1 files changed, 7 insertions, 2 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 676ab394200e..5055b940df5f 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -807,8 +807,13 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
          */
         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;
+                }
         }
 
         /*