[PATCH] Swapless page migration: add R/W migration entries

[linux-2.6-block.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 7e3683fd4f3ca706439ce3bbac5c79b23b19da61..11673c5d2c20236fcdc7f514ad91ac0131cb2a94 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -434,7 +434,9 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
        /* pte contains position in swap or file, so copy. */
        if (unlikely(!pte_present(pte))) {
                if (!pte_file(pte)) {
-                       swap_duplicate(pte_to_swp_entry(pte));
+                       swp_entry_t entry = pte_to_swp_entry(pte);
+
+                       swap_duplicate(entry);
                        /* make sure dst_mm is on swapoff's mmlist. */
                        if (unlikely(list_empty(&dst_mm->mmlist))) {
                                spin_lock(&mmlist_lock);
@@ -443,6 +445,16 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                                                 &src_mm->mmlist);
                                spin_unlock(&mmlist_lock);
                        }
+                       if (is_write_migration_entry(entry) &&
+                                       is_cow_mapping(vm_flags)) {
+                               /*
+                                * COW mappings require pages in both parent
+                                * and child to be set to read.
+                                */
+                               make_migration_entry_read(&entry);
+                               pte = swp_entry_to_pte(entry);
+                               set_pte_at(src_mm, addr, src_pte, pte);
+                       }
                }
                goto out_set_pte;
        }
@@ -1879,6 +1891,10 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
                goto out;
 
        entry = pte_to_swp_entry(orig_pte);
+       if (is_migration_entry(entry)) {
+               migration_entry_wait(mm, pmd, address);
+               goto out;
+       }
        page = lookup_swap_cache(entry);
        if (!page) {
                swapin_readahead(entry, address, vma);