HWPOISON, hugetlb: set/clear PG_hwpoison bits on hugepage

To avoid race condition between concurrent memory errors on identified
hugepage, we atomically test and set PG_hwpoison bit on the head page.
All pages in the error hugepage are considered as hwpoisoned
for now, so set and clear all PG_hwpoison bits in the hugepage
with page lock of the head page held.

Dependency:
  "HWPOISON, hugetlb: enable error handling path for hugepage"

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1ec68c80788..fee648b9d39 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -920,6 +920,22 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
         return ret;
 }
 
+static void set_page_hwpoison_huge_page(struct page *hpage)
+{
+        int i;
+        int nr_pages = 1 << compound_order(hpage);
+        for (i = 0; i < nr_pages; i++)
+                SetPageHWPoison(hpage + i);
+}
+
+static void clear_page_hwpoison_huge_page(struct page *hpage)
+{
+        int i;
+        int nr_pages = 1 << compound_order(hpage);
+        for (i = 0; i < nr_pages; i++)
+                ClearPageHWPoison(hpage + i);
+}
+
 int __memory_failure(unsigned long pfn, int trapno, int flags)
 {
         struct page_state *ps;
@@ -1014,6 +1030,26 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
                 return 0;
         }
 
+        /*
+         * 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)) {
+                action_result(pfn, "hugepage already hardware poisoned",
+                                IGNORED);
+                unlock_page(hpage);
+                put_page(hpage);
+                return 0;
+        }
+        /*
+         * Set PG_hwpoison on all pages in an error hugepage,
+         * because containment is done in hugepage unit for now.
+         * Since we have done TestSetPageHWPoison() for the head page with
+         * page lock held, we can safely set PG_hwpoison bits on tail pages.
+         */
+        if (PageHuge(p))
+                set_page_hwpoison_huge_page(hpage);
+
         wait_on_page_writeback(p);
 
         /*
@@ -1118,6 +1154,8 @@ int unpoison_memory(unsigned long pfn)
                 atomic_long_dec(&mce_bad_pages);
                 freeit = 1;
         }
+        if (PageHuge(p))
+                clear_page_hwpoison_huge_page(page);
         unlock_page(page);
 
         put_page(page);