2 files changed, 28 insertions, 6 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e187454d82f6..b6c1ce3c53b5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1162,7 +1162,12 @@ static void __split_huge_page_refcount(struct page *page)
                 /* after clearing PageTail the gup refcount can be released */
                 smp_mb();
 
-                page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+                /*
+                 * retain hwpoison flag of the poisoned tail page:
+                 *   fix for the unsuitable process killed on Guest Machine(KVM)
+                 *   by the memory-failure.
+                 */
+                page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP | __PG_HWPOISON;
                 page_tail->flags |= (page->flags &
                                      ((1L << PG_referenced) |
                                       (1L << PG_swapbacked) |
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1e9c30b241c3..04158d6f44d4 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -854,6 +854,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
         int ret;
         int kill = 1;
         struct page *hpage = compound_head(p);
+        struct page *ppage;
 
         if (PageReserved(p) || PageSlab(p))
                 return SWAP_SUCCESS;
@@ -894,6 +895,14 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
                 }
         }
 
+        /*
+         * ppage: poisoned page
+         *   if p is regular page(4k page)
+         *        ppage == real poisoned page;
+         *   else p is hugetlb or THP, ppage == head page.
+         */
+        ppage = hpage;
+
         if (PageTransHuge(hpage)) {
                 /*
                  * Verify that this isn't a hugetlbfs head page, the check for
@@ -919,6 +928,8 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
                                 BUG_ON(!PageHWPoison(p));
                                 return SWAP_FAIL;
                         }
+                        /* THP is split, so ppage should be the real poisoned page. */
+                        ppage = p;
                 }
         }
 
@@ -931,12 +942,18 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
          * there's nothing that can be done.
          */
         if (kill)
-                collect_procs(hpage, &tokill);
+                collect_procs(ppage, &tokill);
 
-        ret = try_to_unmap(hpage, ttu);
+        if (hpage != ppage)
+                lock_page_nosync(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(hpage));
+                                pfn, page_mapcount(ppage));
+
+        if (hpage != ppage)
+                unlock_page(ppage);
 
         /*
          * Now that the dirty bit has been propagated to the
@@ -947,7 +964,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
          * use a more force-full uncatchable kill to prevent
          * any accesses to the poisoned memory.
          */
-        kill_procs_ao(&tokill, !!PageDirty(hpage), trapno,
+        kill_procs_ao(&tokill, !!PageDirty(ppage), trapno,
                       ret != SWAP_SUCCESS, p, pfn);
 
         return ret;
@@ -1090,7 +1107,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
          * For error on the tail page, we should set PG_hwpoison
          * on the head page to show that the hugepage is hwpoisoned
          */
-        if (PageTail(p) && TestSetPageHWPoison(hpage)) {
+        if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
                 action_result(pfn, "hugepage already hardware poisoned",
                                 IGNORED);
                 unlock_page(hpage);