hwpoison, hugetlb: lock_page/unlock_page does not match for handling …

…a free hugepage For handling a free hugepage in memory failure, the race will happen if another thread hwpoisoned this hugepage concurrently. So we need to check PageHWPoison instead of !PageHWPoison. If hwpoison_filter(p) returns true or a race happens, then we need to unlock_page(hpage). Signed-off-by: Chen Yucong <[email protected]> Reviewed-by: Naoya Horiguchi <[email protected]> Tested-by: Naoya Horiguchi <[email protected]> Reviewed-by: Andi Kleen <[email protected]> Cc: <[email protected]> [2.6.36+] Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
djekels-zz · May 23, 2014 · b985194 · b985194
1 parent 4b660a7
commit b985194
Showing 1 changed file with 8 additions and 7 deletions.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
@@ -1081,15 +1081,16 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 			return 0;
 		} else if (PageHuge(hpage)) {
 			/*
-			 * Check "just unpoisoned", "filter hit", and
-			 * "race with other subpage."
+			 * Check "filter hit" and "race with other subpage."
 			 */
 			lock_page(hpage);
-			if (!PageHWPoison(hpage)
-			    || (hwpoison_filter(p) && TestClearPageHWPoison(p))
-			    || (p != hpage && TestSetPageHWPoison(hpage))) {
-				atomic_long_sub(nr_pages, &num_poisoned_pages);
-				return 0;
+			if (PageHWPoison(hpage)) {
+				if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
+				    || (p != hpage && TestSetPageHWPoison(hpage))) {
+					atomic_long_sub(nr_pages, &num_poisoned_pages);
+					unlock_page(hpage);
+					return 0;
+				}
 			}
 			set_page_hwpoison_huge_page(hpage);
 			res = dequeue_hwpoisoned_huge_page(hpage);