1 files changed, 9 insertions, 34 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index e5fd5385f0cc..cc367f7e75d8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -395,6 +395,9 @@ void free_swap_and_cache(swp_entry_t entry)
         struct swap_info_struct * p;
         struct page *page = NULL;
 
+        if (is_migration_entry(entry))
+                return;
+
         p = swap_info_get(entry);
         if (p) {
                 if (swap_entry_free(p, swp_offset(entry)) == 1) {
@@ -615,15 +618,6 @@ static int unuse_mm(struct mm_struct *mm,
         return 0;
 }
 
-#ifdef CONFIG_MIGRATION
-int remove_vma_swap(struct vm_area_struct *vma, struct page *page)
-{
-        swp_entry_t entry = { .val = page_private(page) };
-
-        return unuse_vma(vma, entry, page);
-}
-#endif
-
 /*
  * Scan swap_map from current position to next entry still in use.
  * Recycle to start on reaching the end, returning 0 when empty.
@@ -716,7 +710,6 @@ static int try_to_unuse(unsigned int type)
                  */
                 swap_map = &si->swap_map[i];
                 entry = swp_entry(type, i);
-again:
                 page = read_swap_cache_async(entry, NULL, 0);
                 if (!page) {
                         /*
@@ -751,12 +744,6 @@ again:
                 wait_on_page_locked(page);
                 wait_on_page_writeback(page);
                 lock_page(page);
-                if (!PageSwapCache(page)) {
-                        /* Page migration has occured */
-                        unlock_page(page);
-                        page_cache_release(page);
-                        goto again;
-                }
                 wait_on_page_writeback(page);
 
                 /*
@@ -785,10 +772,8 @@ again:
                         while (*swap_map > 1 && !retval &&
                                         (p = p->next) != &start_mm->mmlist) {
                                 mm = list_entry(p, struct mm_struct, mmlist);
-                                if (atomic_inc_return(&mm->mm_users) == 1) {
-                                        atomic_dec(&mm->mm_users);
+                                if (!atomic_inc_not_zero(&mm->mm_users))
                                         continue;
-                                }
                                 spin_unlock(&mmlist_lock);
                                 mmput(prev_mm);
                                 prev_mm = mm;
@@ -1407,19 +1392,7 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
                 if (!(p->flags & SWP_USED))
                         break;
         error = -EPERM;
-        /*
-         * Test if adding another swap device is possible. There are
-         * two limiting factors: 1) the number of bits for the swap
-         * type swp_entry_t definition and 2) the number of bits for
-         * the swap type in the swap ptes as defined by the different
-         * architectures. To honor both limitations a swap entry
-         * with swap offset 0 and swap type ~0UL is created, encoded
-         * to a swap pte, decoded to a swp_entry_t again and finally
-         * the swap type part is extracted. This will mask all bits
-         * from the initial ~0UL that can't be encoded in either the
-         * swp_entry_t or the architecture definition of a swap pte.
-         */
-        if (type > swp_type(pte_to_swp_entry(swp_entry_to_pte(swp_entry(~0UL,0))))) {
+        if (type >= MAX_SWAPFILES) {
                 spin_unlock(&swap_lock);
                 goto out;
         }
@@ -1504,8 +1477,7 @@ asmlinkage long sys_swapon(const char __user * specialfile, int swap_flags)
                 error = -EINVAL;
                 goto bad_swap;
         }
-        page = read_cache_page(mapping, 0,
-                        (filler_t *)mapping->a_ops->readpage, swap_file);
+        page = read_mapping_page(mapping, 0, swap_file);
         if (IS_ERR(page)) {
                 error = PTR_ERR(page);
                 goto bad_swap;
@@ -1709,6 +1681,9 @@ int swap_duplicate(swp_entry_t entry)
         unsigned long offset, type;
         int result = 0;
 
+        if (is_migration_entry(entry))
+                return 1;
+
         type = swp_type(entry);
         if (type >= nr_swapfiles)
                 goto bad_file;