1 files changed, 11 insertions, 10 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b25ed321e667..4f08a2d61487 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;