Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc

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

diff --git a/mm/rmap.c b/mm/rmap.c
index 94a5246..0383acf 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -224,10 +224,14 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 /*
  * Check that @page is mapped at @address into @mm.
  *
+ * If @sync is false, page_check_address may perform a racy check to avoid
+ * the page table lock when the pte is not present (helpful when reclaiming
+ * highly shared pages).
+ *
  * On success returns with pte mapped and locked.
  */
 pte_t *page_check_address(struct page *page, struct mm_struct *mm,
-                         unsigned long address, spinlock_t **ptlp)
+                         unsigned long address, spinlock_t **ptlp, int sync)
 {
        pgd_t *pgd;
        pud_t *pud;
@@ -249,7 +253,7 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm,
 
        pte = pte_offset_map(pmd, address);
        /* Make a quick check before getting the lock */
-       if (!pte_present(*pte)) {
+       if (!sync && !pte_present(*pte)) {
                pte_unmap(pte);
                return NULL;
        }
@@ -281,7 +285,7 @@ static int page_referenced_one(struct page *page,
        if (address == -EFAULT)
                goto out;
 
-       pte = page_check_address(page, mm, address, &ptl);
+       pte = page_check_address(page, mm, address, &ptl, 0);
        if (!pte)
                goto out;
 
@@ -422,7 +426,7 @@ int page_referenced(struct page *page, int is_locked,
                        referenced += page_referenced_anon(page, mem_cont);
                else if (is_locked)
                        referenced += page_referenced_file(page, mem_cont);
-               else if (TestSetPageLocked(page))
+               else if (!trylock_page(page))
                        referenced++;
                else {
                        if (page->mapping)
@@ -450,7 +454,7 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
        if (address == -EFAULT)
                goto out;
 
-       pte = page_check_address(page, mm, address, &ptl);
+       pte = page_check_address(page, mm, address, &ptl, 1);
        if (!pte)
                goto out;
 
@@ -659,23 +663,30 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
                }
 
                /*
-                * It would be tidy to reset the PageAnon mapping here,
-                * but that might overwrite a racing page_add_anon_rmap
-                * which increments mapcount after us but sets mapping
-                * before us: so leave the reset to free_hot_cold_page,
-                * and remember that it's only reliable while mapped.
-                * Leaving it set also helps swapoff to reinstate ptes
-                * faster for those pages still in swapcache.
+                * Now that the last pte has gone, s390 must transfer dirty
+                * flag from storage key to struct page.  We can usually skip
+                * this if the page is anon, so about to be freed; but perhaps
+                * not if it's in swapcache - there might be another pte slot
+                * containing the swap entry, but page not yet written to swap.
                 */
                if ((!PageAnon(page) || PageSwapCache(page)) &&
                    page_test_dirty(page)) {
                        page_clear_dirty(page);
                        set_page_dirty(page);
                }
-               mem_cgroup_uncharge_page(page);
 
+               mem_cgroup_uncharge_page(page);
                __dec_zone_page_state(page,
-                               PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
+                       PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
+               /*
+                * It would be tidy to reset the PageAnon mapping here,
+                * but that might overwrite a racing page_add_anon_rmap
+                * which increments mapcount after us but sets mapping
+                * before us: so leave the reset to free_hot_cold_page,
+                * and remember that it's only reliable while mapped.
+                * Leaving it set also helps swapoff to reinstate ptes
+                * faster for those pages still in swapcache.
+                */
        }
 }
 
@@ -697,7 +708,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
        if (address == -EFAULT)
                goto out;
 
-       pte = page_check_address(page, mm, address, &ptl);
+       pte = page_check_address(page, mm, address, &ptl, 0);
        if (!pte)
                goto out;