[PATCH] delete from_swap_cache BUG_ONs

[pandora-kernel.git] / mm / rmap.c

diff --git a/mm/rmap.c b/mm/rmap.c
index 9827409..facb8cd 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -34,9 +34,8 @@
  *       anon_vma->lock
  *         mm->page_table_lock
  *           zone->lru_lock (in mark_page_accessed)
- *           swap_list_lock (in swap_free etc's swap_info_get)
+ *           swap_lock (in swap_duplicate, swap_info_get)
  *             mmlist_lock (in mmput, drain_mmlist and others)
- *             swap_device_lock (in swap_duplicate, swap_info_get)
  *             mapping->private_lock (in __set_page_dirty_buffers)
  *             inode_lock (in set_page_dirty's __mark_inode_dirty)
  *               sb_lock (within inode_lock in fs/fs-writeback.c)
@@ -247,8 +246,8 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
  *
  * On success returns with mapped pte and locked mm->page_table_lock.
  */
-static pte_t *page_check_address(struct page *page, struct mm_struct *mm,
-                                       unsigned long address)
+pte_t *page_check_address(struct page *page, struct mm_struct *mm,
+                         unsigned long address)
 {
        pgd_t *pgd;
        pud_t *pud;
@@ -539,27 +538,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
                goto out_unmap;
        }
 
-       /*
-        * Don't pull an anonymous page out from under get_user_pages.
-        * GUP carefully breaks COW and raises page count (while holding
-        * page_table_lock, as we have here) to make sure that the page
-        * cannot be freed.  If we unmap that page here, a user write
-        * access to the virtual address will bring back the page, but
-        * its raised count will (ironically) be taken to mean it's not
-        * an exclusive swap page, do_wp_page will replace it by a copy
-        * page, and the user never get to see the data GUP was holding
-        * the original page for.
-        *
-        * This test is also useful for when swapoff (unuse_process) has
-        * to drop page lock: its reference to the page stops existing
-        * ptes from being unmapped, so swapoff can make progress.
-        */
-       if (PageSwapCache(page) &&
-           page_count(page) != page_mapcount(page) + 2) {
-               ret = SWAP_FAIL;
-               goto out_unmap;
-       }
-
        /* Nuke the page table entry. */
        flush_cache_page(vma, address, page_to_pfn(page));
        pteval = ptep_clear_flush(vma, address, pte);