memcg: add accessor to mem_cgroup.css

[safe/jmp/linux-2.6] / mm / swapfile.c

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d5eb2e8..6c0585b 100644 (file)
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -22,6 +22,7 @@
 #include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/module.h>
+#include <linux/ksm.h>
 #include <linux/rmap.h>
 #include <linux/security.h>
 #include <linux/backing-dev.h>
@@ -650,6 +651,8 @@ int reuse_swap_page(struct page *page)
        int count;
 
        VM_BUG_ON(!PageLocked(page));
+       if (unlikely(PageKsm(page)))
+               return 0;
        count = page_mapcount(page);
        if (count <= 1 && PageSwapCache(page)) {
                count += page_swapcount(page);
@@ -658,7 +661,7 @@ int reuse_swap_page(struct page *page)
                        SetPageDirty(page);
                }
        }
-       return count == 1;
+       return count <= 1;
 }
 
 /*
@@ -938,7 +941,7 @@ static int unuse_vma(struct vm_area_struct *vma,
        unsigned long addr, end, next;
        int ret;
 
-       if (page->mapping) {
+       if (page_anon_vma(page)) {
                addr = page_address_in_vma(page, vma);
                if (addr == -EFAULT)
                        return 0;
@@ -1185,6 +1188,12 @@ static int try_to_unuse(unsigned int type)
                 * read from disk into another page.  Splitting into two
                 * pages would be incorrect if swap supported "shared
                 * private" pages, but they are handled by tmpfs files.
+                *
+                * Given how unuse_vma() targets one particular offset
+                * in an anon_vma, once the anon_vma has been determined,
+                * this splitting happens to be just what is needed to
+                * handle where KSM pages have been swapped out: re-reading
+                * is unnecessarily slow, but we can fix that later on.
                 */
                if (swap_count(*swap_map) &&
                     PageDirty(page) && PageSwapCache(page)) {