mm: hwpoison: introduce memory_failure_hugetlb()

memory_failure() is a big function and hard to maintain.  Handling
hugetlb- and non-hugetlb- case in a single function is not good, so this
patch separates PageHuge() branch into a new function, which saves many
PageHuge() check.

Link: http://lkml.kernel.org/r/1496305019-5493-7-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 8a7b394..5db3827 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1009,6 +1009,76 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
        return unmap_success;
 }
 
+static int memory_failure_hugetlb(unsigned long pfn, int trapno, int flags)
+{
+       struct page_state *ps;
+       struct page *p = pfn_to_page(pfn);
+       struct page *head = compound_head(p);
+       int res;
+       unsigned long page_flags;
+
+       if (TestSetPageHWPoison(head)) {
+               pr_err("Memory failure: %#lx: already hardware poisoned\n",
+                      pfn);
+               return 0;
+       }
+
+       num_poisoned_pages_inc();
+
+       if (!(flags & MF_COUNT_INCREASED) && !get_hwpoison_page(p)) {
+               /*
+                * Check "filter hit" and "race with other subpage."
+                */
+               lock_page(head);
+               if (PageHWPoison(head)) {
+                       if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
+                           || (p != head && TestSetPageHWPoison(head))) {
+                               num_poisoned_pages_dec();
+                               unlock_page(head);
+                               return 0;
+                       }
+               }
+               unlock_page(head);
+               dissolve_free_huge_page(p);
+               action_result(pfn, MF_MSG_FREE_HUGE, MF_DELAYED);
+               return 0;
+       }
+
+       lock_page(head);
+       page_flags = head->flags;
+
+       if (!PageHWPoison(head)) {
+               pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
+               num_poisoned_pages_dec();
+               unlock_page(head);
+               put_hwpoison_page(head);
+               return 0;
+       }
+
+       if (!hwpoison_user_mappings(p, pfn, trapno, flags, &head)) {
+               action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
+               res = -EBUSY;
+               goto out;
+       }
+
+       res = -EBUSY;
+
+       for (ps = error_states;; ps++)
+               if ((p->flags & ps->mask) == ps->res)
+                       break;
+
+       page_flags |= (p->flags & (1UL << PG_dirty));
+
+       if (!ps->mask)
+               for (ps = error_states;; ps++)
+                       if ((page_flags & ps->mask) == ps->res)
+                               break;
+       res = page_action(ps, p, pfn);
+out:
+       unlock_page(head);
+       return res;
+}
+
 /**
  * memory_failure - Handle memory failure of a page.
  * @pfn: Page Number of the corrupted page
@@ -1046,33 +1116,22 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
        }
 
        p = pfn_to_page(pfn);
-       orig_head = hpage = compound_head(p);
-
-       /* tmporary check code, to be updated in later patches */
-       if (PageHuge(p)) {
-               if (TestSetPageHWPoison(hpage)) {
-                       pr_err("Memory failure: %#lx: already hardware poisoned\n", pfn);
-                       return 0;
-               }
-               goto tmp;
-       }
+       if (PageHuge(p))
+               return memory_failure_hugetlb(pfn, trapno, flags);
        if (TestSetPageHWPoison(p)) {
                pr_err("Memory failure: %#lx: already hardware poisoned\n",
                        pfn);
                return 0;
        }
 
-tmp:
+       orig_head = hpage = compound_head(p);
        num_poisoned_pages_inc();
 
        /*
         * 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 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.
+        * 2) 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.
@@ -1083,31 +1142,13 @@ tmp:
                if (is_free_buddy_page(p)) {
                        action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
                        return 0;
-               } else if (PageHuge(hpage)) {
-                       /*
-                        * Check "filter hit" and "race with other subpage."
-                        */
-                       lock_page(hpage);
-                       if (PageHWPoison(hpage)) {
-                               if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
-                                   || (p != hpage && TestSetPageHWPoison(hpage))) {
-                                       num_poisoned_pages_dec();
-                                       unlock_page(hpage);
-                                       return 0;
-                               }
-                       }
-                       res = dequeue_hwpoisoned_huge_page(hpage);
-                       action_result(pfn, MF_MSG_FREE_HUGE,
-                                     res ? MF_IGNORED : MF_DELAYED);
-                       unlock_page(hpage);
-                       return res;
                } else {
                        action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
                        return -EBUSY;
                }
        }
 
-       if (!PageHuge(p) && PageTransHuge(hpage)) {
+       if (PageTransHuge(hpage)) {
                lock_page(p);
                if (!PageAnon(p) || unlikely(split_huge_page(p))) {
                        unlock_page(p);
@@ -1145,7 +1186,7 @@ tmp:
                return 0;
        }
 
-       lock_page(hpage);
+       lock_page(p);
 
        /*
         * The page could have changed compound pages during the locking.
@@ -1175,32 +1216,21 @@ tmp:
        if (!PageHWPoison(p)) {
                pr_err("Memory failure: %#lx: just unpoisoned\n", pfn);
                num_poisoned_pages_dec();
-               unlock_page(hpage);
-               put_hwpoison_page(hpage);
+               unlock_page(p);
+               put_hwpoison_page(p);
                return 0;
        }
        if (hwpoison_filter(p)) {
                if (TestClearPageHWPoison(p))
                        num_poisoned_pages_dec();
-               unlock_page(hpage);
-               put_hwpoison_page(hpage);
+               unlock_page(p);
+               put_hwpoison_page(p);
                return 0;
        }
 
-       if (!PageHuge(p) && !PageTransTail(p) && !PageLRU(p))
+       if (!PageTransTail(p) && !PageLRU(p))
                goto identify_page_state;
 
-       /*
-        * For error on the tail page, we should set PG_hwpoison
-        * on the head page to show that the hugepage is hwpoisoned
-        */
-       if (PageHuge(p) && PageTail(p) && TestSetPageHWPoison(hpage)) {
-               action_result(pfn, MF_MSG_POISONED_HUGE, MF_IGNORED);
-               unlock_page(hpage);
-               put_hwpoison_page(hpage);
-               return 0;
-       }
-
        /*
         * It's very difficult to mess with pages currently under IO
         * and in many cases impossible, so we just avoid it here.
@@ -1248,7 +1278,7 @@ identify_page_state:
                                break;
        res = page_action(ps, p, pfn);
 out:
-       unlock_page(hpage);
+       unlock_page(p);
        return res;
 }
 EXPORT_SYMBOL_GPL(memory_failure);