Merge branch 'hwpoison-2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6

* 'hwpoison-2.6.32' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6:
  HWPOISON: fix invalid page count in printk output
  HWPOISON: Allow schedule_on_each_cpu() from keventd
  HWPOISON: fix/proc/meminfo alignment
  HWPOISON: fix oops on ksm pages
  HWPOISON: Fix page count leak in hwpoison late kill in do_swap_page
  HWPOISON: return early on non-LRU pages
  HWPOISON: Add brief hwpoison description to Documentation
  HWPOISON: Clean up PR_MCE_KILL interface

2 files changed, 31 insertions, 28 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 7fc2130d273..dacc6418387 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -371,9 +371,6 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn)
         int ret = FAILED;
         struct address_space *mapping;
 
-        if (!isolate_lru_page(p))
-                page_cache_release(p);
-
         /*
          * For anonymous pages we're done the only reference left
          * should be the one m_f() holds.
@@ -499,30 +496,18 @@ static int me_pagecache_dirty(struct page *p, unsigned long pfn)
  */
 static int me_swapcache_dirty(struct page *p, unsigned long pfn)
 {
-        int ret = FAILED;
-
         ClearPageDirty(p);
         /* Trigger EIO in shmem: */
         ClearPageUptodate(p);
 
-        if (!isolate_lru_page(p)) {
-                page_cache_release(p);
-                ret = DELAYED;
-        }
-
-        return ret;
+        return DELAYED;
 }
 
 static int me_swapcache_clean(struct page *p, unsigned long pfn)
 {
-        int ret = FAILED;
-
-        if (!isolate_lru_page(p)) {
-                page_cache_release(p);
-                ret = RECOVERED;
-        }
         delete_from_swap_cache(p);
-        return ret;
+
+        return RECOVERED;
 }
 
 /*
@@ -612,8 +597,6 @@ static struct page_state {
         { 0,            0,              "unknown page state",   me_unknown },
 };
 
-#undef lru
-
 static void action_result(unsigned long pfn, char *msg, int result)
 {
         struct page *page = NULL;
@@ -630,13 +613,16 @@ static int page_action(struct page_state *ps, struct page *p,
                         unsigned long pfn, int ref)
 {
         int result;
+        int count;
 
         result = ps->action(p, pfn);
         action_result(pfn, ps->msg, result);
-        if (page_count(p) != 1 + ref)
+
+        count = page_count(p) - 1 - ref;
+        if (count != 0)
                 printk(KERN_ERR
                        "MCE %#lx: %s page still referenced by %d users\n",
-                       pfn, ps->msg, page_count(p) - 1);
+                       pfn, ps->msg, count);
 
         /* Could do more checks here if page looks ok */
         /*
@@ -665,9 +651,6 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
         if (PageReserved(p) || PageCompound(p) || PageSlab(p) || PageKsm(p))
                 return;
 
-        if (!PageLRU(p))
-                lru_add_drain_all();
-
         /*
          * This check implies we don't kill processes if their pages
          * are in the swap cache early. Those are always late kills.
@@ -739,6 +722,7 @@ static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
 
 int __memory_failure(unsigned long pfn, int trapno, int ref)
 {
+        unsigned long lru_flag;
         struct page_state *ps;
         struct page *p;
         int res;
@@ -776,6 +760,24 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
         }
 
         /*
+         * We ignore non-LRU pages for good reasons.
+         * - PG_locked is only well defined for LRU pages and a few others
+         * - to avoid races with __set_page_locked()
+         * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
+         * The check (unnecessarily) ignores LRU pages being isolated and
+         * walked by the page reclaim code, however that's not a big loss.
+         */
+        if (!PageLRU(p))
+                lru_add_drain_all();
+        lru_flag = p->flags & lru;
+        if (isolate_lru_page(p)) {
+                action_result(pfn, "non LRU", IGNORED);
+                put_page(p);
+                return -EBUSY;
+        }
+        page_cache_release(p);
+
+        /*
          * Lock the page and wait for writeback to finish.
          * It's very difficult to mess with pages currently under IO
          * and in many cases impossible, so we just avoid it here.
@@ -791,7 +793,7 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
         /*
          * Torn down by someone else?
          */
-        if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
+        if ((lru_flag & lru) && !PageSwapCache(p) && p->mapping == NULL) {
                 action_result(pfn, "already truncated LRU", IGNORED);
                 res = 0;
                 goto out;
@@ -799,7 +801,7 @@ int __memory_failure(unsigned long pfn, int trapno, int ref)
 
         res = -EBUSY;
         for (ps = error_states;; ps++) {
-                if ((p->flags & ps->mask) == ps->res) {
+                if (((p->flags | lru_flag)& ps->mask) == ps->res) {
                         res = page_action(ps, p, pfn, ref);
                         break;
                 }
diff --git a/mm/memory.c b/mm/memory.c
index 60ea601e03e..6ab19dd4a19 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2542,7 +2542,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
         } else if (PageHWPoison(page)) {
                 ret = VM_FAULT_HWPOISON;
                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
-                goto out;
+                goto out_release;
         }
 
         lock_page(page);
@@ -2614,6 +2614,7 @@ out_nomap:
         pte_unmap_unlock(page_table, ptl);
 out_page:
         unlock_page(page);
+out_release:
         page_cache_release(page);
         return ret;
 }