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>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1ec68c8..fee648b 100644 (file)
--- 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);