[PATCH] Allow migration of mlocked pages

Hugh clarified the role of VM_LOCKED.  So we can now implement page
migration for mlocked pages.

Allow the migration of mlocked pages.  This means that try_to_unmap must
unmap mlocked pages in the migration case.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index 0576c053598803303beb6c0244ad06dffdef0f69..3f1e0c2c942c90d59c565e92ee119479861f7c47 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -616,15 +616,13 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private,
        /*
         * Establish migration ptes or remove ptes
         */
-       if (try_to_unmap(page, 1) != SWAP_FAIL) {
-               if (!page_mapped(page))
-                       rc = move_to_new_page(newpage, page);
-       } else
-               /* A vma has VM_LOCKED set -> permanent failure */
-               rc = -EPERM;
+       try_to_unmap(page, 1);
+       if (!page_mapped(page))
+               rc = move_to_new_page(newpage, page);
 
        if (rc)
                remove_migration_ptes(page, page);
+
 unlock:
        unlock_page(page);
 

diff --git a/mm/rmap.c b/mm/rmap.c
index 882a85826bb2d2c6cf5ef61ee7d3fb982b125e9b..e76909e880ca8c2847b3b405f03ed56b453a4a44 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -562,9 +562,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
         * If it's recently referenced (perhaps page_referenced
         * skipped over this mm) then we should reactivate it.
         */
-       if ((vma->vm_flags & VM_LOCKED) ||
-                       (ptep_clear_flush_young(vma, address, pte)
-                               && !migration)) {
+       if (!migration && ((vma->vm_flags & VM_LOCKED) ||
+                       (ptep_clear_flush_young(vma, address, pte)))) {
                ret = SWAP_FAIL;
                goto out_unmap;
        }
@@ -771,7 +770,7 @@ static int try_to_unmap_file(struct page *page, int migration)
 
        list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
                                                shared.vm_set.list) {
-               if (vma->vm_flags & VM_LOCKED)
+               if ((vma->vm_flags & VM_LOCKED) && !migration)
                        continue;
                cursor = (unsigned long) vma->vm_private_data;
                if (cursor > max_nl_cursor)
@@ -805,7 +804,7 @@ static int try_to_unmap_file(struct page *page, int migration)
        do {
                list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
                                                shared.vm_set.list) {
-                       if (vma->vm_flags & VM_LOCKED)
+                       if ((vma->vm_flags & VM_LOCKED) && !migration)
                                continue;
                        cursor = (unsigned long) vma->vm_private_data;
                        while ( cursor < max_nl_cursor &&