page migration: Fail with error if swap not setup

Christoph Lameter
2006-03-15T03:05:33Z

Currently the migration of anonymous pages will silently fail if no swap
is setup. This patch makes page migration functions check for available
swap and fail with -ENODEV if no swap space is available.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.16-rc6/mm/mempolicy.c
===================================================================
--- linux-2.6.16-rc6.orig/mm/mempolicy.c 2006-03-14 16:31:15.000000000 -0800
+++ linux-2.6.16-rc6/mm/mempolicy.c 2006-03-14 17:25:09.000000000 -0800
@@ -330,9 +330,14 @@ check_range(struct mm_struct *mm, unsign
int err;
struct vm_area_struct *first, *vma, *prev;

- /* Clear the LRU lists so pages can be isolated */
- if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+ if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
+ /* Must have available swap entries for migration */
+ if (nr_swap_pages <=0)
+ return ERR_PTR(-ENODEV);
+
+ /* Clear the LRU lists so pages can be isolated */
lru_add_drain_all();
+ }

first = find_vma(mm, start);
if (!first)