Merge branch 'hwpoison-hugepages' into hwpoison

Conflicts:
	mm/memory-failure.c

1 files changed, 93 insertions, 9 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 2044fe8920c2..44a8cefeae6e 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -697,11 +697,10 @@ 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)
 {
+        int res = 0;
         struct page *hpage = compound_head(p);
         /*
          * We can safely recover from error on free or reserved (i.e.
@@ -714,8 +713,9 @@ static int me_huge_page(struct page *p, unsigned long pfn)
          * so there is no race between isolation and mapping/unmapping.
          */
         if (!(page_mapping(hpage) || PageAnon(hpage))) {
-                __isolate_hwpoisoned_huge_page(hpage);
-                return RECOVERED;
+                res = dequeue_hwpoisoned_huge_page(hpage);
+                if (!res)
+                        return RECOVERED;
         }
         return DELAYED;
 }
@@ -972,7 +972,10 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
          * We need/can do nothing about count=0 pages.
          * 1) it's a free page, and therefore in safe hand:
          *    prep_new_page() will be the gate keeper.
-         * 2) it's part of a non-compound high order page.
+         * 2) it's a free hugepage, which is also safe:
+         *    an affected hugepage will be dequeued from hugepage freelist,
+         *    so there's no concern about reusing it ever after.
+         * 3) it's part of a non-compound high order page.
          *    Implies some kernel user: cannot stop them from
          *    R/W the page; let's pray that the page has been
          *    used and will be freed some time later.
@@ -984,6 +987,24 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
                 if (is_free_buddy_page(p)) {
                         action_result(pfn, "free buddy", DELAYED);
                         return 0;
+                } else if (PageHuge(hpage)) {
+                        /*
+                         * Check "just unpoisoned", "filter hit", and
+                         * "race with other subpage."
+                         */
+                        lock_page_nosync(hpage);
+                        if (!PageHWPoison(hpage)
+                            || (hwpoison_filter(p) && TestClearPageHWPoison(p))
+                            || (p != hpage && TestSetPageHWPoison(hpage))) {
+                                atomic_long_sub(nr_pages, &mce_bad_pages);
+                                return 0;
+                        }
+                        set_page_hwpoison_huge_page(hpage);
+                        res = dequeue_hwpoisoned_huge_page(hpage);
+                        action_result(pfn, "free huge",
+                                      res ? IGNORED : DELAYED);
+                        unlock_page(hpage);
+                        return res;
                 } else {
                         action_result(pfn, "high order kernel", IGNORED);
                         return -EBUSY;
@@ -1145,6 +1166,16 @@ int unpoison_memory(unsigned long pfn)
         nr_pages = 1 << compound_order(page);
 
         if (!get_page_unless_zero(page)) {
+                /*
+                 * Since HWPoisoned hugepage should have non-zero refcount,
+                 * race between memory failure and unpoison seems to happen.
+                 * In such case unpoison fails and memory failure runs
+                 * to the end.
+                 */
+                if (PageHuge(page)) {
+                        pr_debug("MCE: Memory failure is now running on free hugepage %#lx\n", pfn);
+                        return 0;
+                }
                 if (TestClearPageHWPoison(p))
                         atomic_long_sub(nr_pages, &mce_bad_pages);
                 pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
@@ -1162,9 +1193,9 @@ int unpoison_memory(unsigned long pfn)
                 pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
                 atomic_long_sub(nr_pages, &mce_bad_pages);
                 freeit = 1;
+                if (PageHuge(page))
+                        clear_page_hwpoison_huge_page(page);
         }
-        if (PageHuge(p))
-                clear_page_hwpoison_huge_page(page);
         unlock_page(page);
 
         put_page(page);
@@ -1178,7 +1209,11 @@ 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);
 }
 
 /*
@@ -1206,8 +1241,15 @@ 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_info("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_info("get_any_page: %#lx free buddy page\n", pfn);
                         /* Set hwpoison bit while page is still isolated */
                         SetPageHWPoison(p);
@@ -1226,6 +1268,45 @@ 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
@@ -1253,6 +1334,9 @@ 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;