mm: fix status code which move_pages() returns for zero page
The manpage for move_pages(2) specifies that status code for zero page is
supposed to be -EFAULT. Currently kernel return -ENOENT in this case.
follow_page() can do it for us, if we would ask for FOLL_DUMP. The use of
FOLL_DUMP also means that the upper layer page tables pages are no longer
allocated.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/migrate.c b/mm/migrate.c
index eb426710..5c08cab 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1226,7 +1226,9 @@
if (!vma || pp->addr < vma->vm_start || !vma_migratable(vma))
goto set_status;
- page = follow_page(vma, pp->addr, FOLL_GET|FOLL_SPLIT);
+ /* FOLL_DUMP to ignore special (like zero) pages */
+ page = follow_page(vma, pp->addr,
+ FOLL_GET | FOLL_SPLIT | FOLL_DUMP);
err = PTR_ERR(page);
if (IS_ERR(page))
@@ -1236,10 +1238,6 @@
if (!page)
goto set_status;
- /* Use PageReserved to check for zero page */
- if (PageReserved(page))
- goto put_and_set;
-
pp->page = page;
err = page_to_nid(page);
@@ -1396,18 +1394,14 @@
if (!vma || addr < vma->vm_start)
goto set_status;
- page = follow_page(vma, addr, 0);
+ /* FOLL_DUMP to ignore special (like zero) pages */
+ page = follow_page(vma, addr, FOLL_DUMP);
err = PTR_ERR(page);
if (IS_ERR(page))
goto set_status;
- err = -ENOENT;
- /* Use PageReserved to check for zero page */
- if (!page || PageReserved(page))
- goto set_status;
-
- err = page_to_nid(page);
+ err = page ? page_to_nid(page) : -ENOENT;
set_status:
*status = err;