X-Git-Url: http://pileus.org/git/?a=blobdiff_plain;f=mm%2Fmemory-failure.c;h=4f08a2d61487f3c45dc01638c31b6aff689ce6e7;hb=1f42db786b14a31bf807fc41ee5583a00c08fcb1;hp=b25ed321e66746824267db5a127f2d5c8c0c519d;hpb=93abdb7785503c269e73e811f3c7fd23a9243b14;p=~andy%2Flinux

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b25ed321e66..4f08a2d6148 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -856,14 +856,14 @@ static int page_action(struct page_state *ps, struct page *p,
  * the pages and send SIGBUS to the processes if the data was dirty.
  */
 static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
-				  int trapno, int flags)
+				  int trapno, int flags, struct page **hpagep)
 {
 	enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
 	struct address_space *mapping;
 	LIST_HEAD(tokill);
 	int ret;
 	int kill = 1, forcekill;
-	struct page *hpage = compound_head(p);
+	struct page *hpage = *hpagep;
 	struct page *ppage;
 
 	if (PageReserved(p) || PageSlab(p))
@@ -942,11 +942,14 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 			 * We pinned the head page for hwpoison handling,
 			 * now we split the thp and we are interested in
 			 * the hwpoisoned raw page, so move the refcount
-			 * to it.
+			 * to it. Similarly, page lock is shifted.
 			 */
 			if (hpage != p) {
 				put_page(hpage);
 				get_page(p);
+				lock_page(p);
+				unlock_page(hpage);
+				*hpagep = p;
 			}
 			/* THP is split, so ppage should be the real poisoned page. */
 			ppage = p;
@@ -964,17 +967,11 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	if (kill)
 		collect_procs(ppage, &tokill);
 
-	if (hpage != ppage)
-		lock_page(ppage);
-
 	ret = try_to_unmap(ppage, ttu);
 	if (ret != SWAP_SUCCESS)
 		printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
 				pfn, page_mapcount(ppage));
 
-	if (hpage != ppage)
-		unlock_page(ppage);
-
 	/*
 	 * Now that the dirty bit has been propagated to the
 	 * struct page and all unmaps done we can decide if
@@ -1193,8 +1190,12 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 	/*
 	 * Now take care of user space mappings.
 	 * Abort on fail: __delete_from_page_cache() assumes unmapped page.
+	 *
+	 * When the raw error page is thp tail page, hpage points to the raw
+	 * page after thp split.
 	 */
-	if (hwpoison_user_mappings(p, pfn, trapno, flags) != SWAP_SUCCESS) {
+	if (hwpoison_user_mappings(p, pfn, trapno, flags, &hpage)
+	    != SWAP_SUCCESS) {
 		printk(KERN_ERR "MCE %#lx: cannot unmap page, give up\n", pfn);
 		res = -EBUSY;
 		goto out;