[PATCH] pfnmap: do_no_page BUG_ON again

Use copy_user_highpage directly instead of cow_user_page in do_no_page:
in the immediately following page_cache_release, and elsewhere, it is
assuming that new_page is normal.  If any VM_PFNMAP driver can get to
do_no_page, it's just a BUG (but not in the case of do_anonymous_page).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/memory.c b/mm/memory.c
index ae259b6e5a211da3f2e7841e070de12ded108fa1..5bfa52a986305dc5af148537782ea375bbce19dc 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2009,6 +2009,8 @@ static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
        int anon = 0;
 
        pte_unmap(page_table);
+       BUG_ON(vma->vm_flags & VM_PFNMAP);
+
        if (vma->vm_file) {
                mapping = vma->vm_file->f_mapping;
                sequence = mapping->truncate_count;
@@ -2041,7 +2043,7 @@ retry:
                page = alloc_page_vma(GFP_HIGHUSER, vma, address);
                if (!page)
                        goto oom;
-               cow_user_page(page, new_page, address);
+               copy_user_highpage(page, new_page, address);
                page_cache_release(new_page);
                new_page = page;
                anon = 1;