1 files changed, 50 insertions, 12 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index d85a99d28c..67f0e20b10 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -52,6 +52,7 @@
 #include <linux/init.h>
 #include <linux/rmap.h>
 #include <linux/rcupdate.h>
+#include <linux/module.h>
 
 #include <asm/tlbflush.h>
 
@@ -205,6 +206,44 @@ out:
         return anon_vma;
 }
 
+#ifdef CONFIG_MIGRATION
+/*
+ * Remove an anonymous page from swap replacing the swap pte's
+ * through real pte's pointing to valid pages and then releasing
+ * the page from the swap cache.
+ *
+ * Must hold page lock on page and mmap_sem of one vma that contains
+ * the page.
+ */
+void remove_from_swap(struct page *page)
+{
+        struct anon_vma *anon_vma;
+        struct vm_area_struct *vma;
+        unsigned long mapping;
+
+        if (!PageSwapCache(page))
+                return;
+
+        mapping = (unsigned long)page->mapping;
+
+        if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0)
+                return;
+
+        /*
+         * We hold the mmap_sem lock. So no need to call page_lock_anon_vma.
+         */
+        anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON);
+        spin_lock(&anon_vma->lock);
+
+        list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
+                remove_vma_swap(vma, page);
+
+        spin_unlock(&anon_vma->lock);
+        delete_from_swap_cache(page);
+}
+EXPORT_SYMBOL(remove_from_swap);
+#endif
+
 /*
  * At what user virtual address is page expected in vma?
  */
@@ -498,9 +537,6 @@ void page_add_new_anon_rmap(struct page *page,
  */
 void page_add_file_rmap(struct page *page)
 {
-        BUG_ON(PageAnon(page));
-        BUG_ON(!pfn_valid(page_to_pfn(page)));
-
         if (atomic_inc_and_test(&page->_mapcount))
                 __inc_page_state(nr_mapped);
 }
@@ -541,7 +577,8 @@ void page_remove_rmap(struct page *page)
  * Subfunctions of try_to_unmap: try_to_unmap_one called
  * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
  */
-static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
+static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
+                                int ignore_refs)
 {
         struct mm_struct *mm = vma->vm_mm;
         unsigned long address;
@@ -564,7 +601,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
          * skipped over this mm) then we should reactivate it.
          */
         if ((vma->vm_flags & VM_LOCKED) ||
-                        ptep_clear_flush_young(vma, address, pte)) {
+                        (ptep_clear_flush_young(vma, address, pte)
+                                && !ignore_refs)) {
                 ret = SWAP_FAIL;
                 goto out_unmap;
         }
@@ -698,7 +736,7 @@ static void try_to_unmap_cluster(unsigned long cursor,
         pte_unmap_unlock(pte - 1, ptl);
 }
 
-static int try_to_unmap_anon(struct page *page)
+static int try_to_unmap_anon(struct page *page, int ignore_refs)
 {
         struct anon_vma *anon_vma;
         struct vm_area_struct *vma;
@@ -709,7 +747,7 @@ static int try_to_unmap_anon(struct page *page)
                 return ret;
 
         list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
-                ret = try_to_unmap_one(page, vma);
+                ret = try_to_unmap_one(page, vma, ignore_refs);
                 if (ret == SWAP_FAIL || !page_mapped(page))
                         break;
         }
@@ -726,7 +764,7 @@ static int try_to_unmap_anon(struct page *page)
  *
  * This function is only called from try_to_unmap for object-based pages.
  */
-static int try_to_unmap_file(struct page *page)
+static int try_to_unmap_file(struct page *page, int ignore_refs)
 {
         struct address_space *mapping = page->mapping;
         pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
@@ -740,7 +778,7 @@ static int try_to_unmap_file(struct page *page)
 
         spin_lock(&mapping->i_mmap_lock);
         vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
-                ret = try_to_unmap_one(page, vma);
+                ret = try_to_unmap_one(page, vma, ignore_refs);
                 if (ret == SWAP_FAIL || !page_mapped(page))
                         goto out;
         }
@@ -825,16 +863,16 @@ out:
  * SWAP_AGAIN   - we missed a mapping, try again later
  * SWAP_FAIL    - the page is unswappable
  */
-int try_to_unmap(struct page *page)
+int try_to_unmap(struct page *page, int ignore_refs)
 {
         int ret;
 
         BUG_ON(!PageLocked(page));
 
         if (PageAnon(page))
-                ret = try_to_unmap_anon(page);
+                ret = try_to_unmap_anon(page, ignore_refs);
         else
-                ret = try_to_unmap_file(page);
+                ret = try_to_unmap_file(page, ignore_refs);
 
         if (!page_mapped(page))
                 ret = SWAP_SUCCESS;