HWPOISON, hugetlb: soft offlining for hugepage

This patch extends soft offlining framework to support hugepage.
When memory corrected errors occur repeatedly on a hugepage,
we can choose to stop using it by migrating data onto another hugepage
and disabling the original (maybe half-broken) one.

ChangeLog since v4:
- branch soft_offline_page() for hugepage

ChangeLog since v3:
- remove comment about "ToDo: hugepage soft-offline"

ChangeLog since v2:
- move refcount handling into isolate_lru_page()

ChangeLog since v1:
- add double check in isolating hwpoisoned hugepage
- define free/non-free checker for hugepage
- postpone calling put_page() for hugepage in soft_offline_page()

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 55 insertions, 4 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 333f87da1845..74eb425010af 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -693,8 +693,6 @@ static int me_swapcache_clean(struct page *p, unsigned long pfn)
  * Issues:
  * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
  *   To narrow down kill region to one page, we need to break up pmd.
- * - To support soft-offlining for hugepage, we need to support hugepage
- *   migration.
  */
 static int me_huge_page(struct page *p, unsigned long pfn)
 {
@@ -1220,7 +1218,11 @@ EXPORT_SYMBOL(unpoison_memory);
 static struct page *new_page(struct page *p, unsigned long private, int **x)
 {
         int nid = page_to_nid(p);
-        return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
+        if (PageHuge(p))
+                return alloc_huge_page_node(page_hstate(compound_head(p)),
+                                                   nid);
+        else
+                return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
 }
 
 /*
@@ -1248,8 +1250,15 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
          * was free.
          */
         set_migratetype_isolate(p);
+        /*
+         * When the target page is a free hugepage, just remove it
+         * from free hugepage list.
+         */
         if (!get_page_unless_zero(compound_head(p))) {
-                if (is_free_buddy_page(p)) {
+                if (PageHuge(p)) {
+                        pr_debug("get_any_page: %#lx free huge page\n", pfn);
+                        ret = dequeue_hwpoisoned_huge_page(compound_head(p));
+                } else if (is_free_buddy_page(p)) {
                         pr_debug("get_any_page: %#lx free buddy page\n", pfn);
                         /* Set hwpoison bit while page is still isolated */
                         SetPageHWPoison(p);
@@ -1268,6 +1277,45 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
         return ret;
 }
 
+static int soft_offline_huge_page(struct page *page, int flags)
+{
+        int ret;
+        unsigned long pfn = page_to_pfn(page);
+        struct page *hpage = compound_head(page);
+        LIST_HEAD(pagelist);
+
+        ret = get_any_page(page, pfn, flags);
+        if (ret < 0)
+                return ret;
+        if (ret == 0)
+                goto done;
+
+        if (PageHWPoison(hpage)) {
+                put_page(hpage);
+                pr_debug("soft offline: %#lx hugepage already poisoned\n", pfn);
+                return -EBUSY;
+        }
+
+        /* Keep page count to indicate a given hugepage is isolated. */
+
+        list_add(&hpage->lru, &pagelist);
+        ret = migrate_huge_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
+        if (ret) {
+                pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
+                         pfn, ret, page->flags);
+                if (ret > 0)
+                        ret = -EIO;
+                return ret;
+        }
+done:
+        if (!PageHWPoison(hpage))
+                atomic_long_add(1 << compound_order(hpage), &mce_bad_pages);
+        set_page_hwpoison_huge_page(hpage);
+        dequeue_hwpoisoned_huge_page(hpage);
+        /* keep elevated page count for bad page */
+        return ret;
+}
+
 /**
  * soft_offline_page - Soft offline a page.
  * @page: page to offline
@@ -1295,6 +1343,9 @@ int soft_offline_page(struct page *page, int flags)
         int ret;
         unsigned long pfn = page_to_pfn(page);
 
+        if (PageHuge(page))
+                return soft_offline_huge_page(page, flags);
+
         ret = get_any_page(page, pfn, flags);
         if (ret < 0)
                 return ret;