[RFC 6/6] mm: enable MADV_FREE for swapless system

[Shaohua Li]

Now MADV_FREE pages can be easily reclaimed even for swapless system. We
can safely enable MADV_FREE for all systems.

Cc: Michal Hocko <mho...@suse.com>
Cc: Minchan Kim <minc...@kernel.org>
Cc: Hugh Dickins <hu...@google.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Rik van Riel <r...@redhat.com>
Cc: Mel Gorman <mgor...@techsingularity.net>
Signed-off-by: Shaohua Li <s...@fb.com>
---
 mm/madvise.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 78b4b02..047cfd4 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -579,13 +579,7 @@ madvise_vma(struct vm_area_struct *vma, struct 
vm_area_struct **prev,
        case MADV_WILLNEED:
                return madvise_willneed(vma, prev, start, end);
        case MADV_FREE:
-               /*
-                * XXX: In this implementation, MADV_FREE works like
-                * MADV_DONTNEED on swapless system or full swap.
-                */
-               if (get_nr_swap_pages() > 0)
-                       return madvise_free(vma, prev, start, end);
-               /* passthrough */
+               return madvise_free(vma, prev, start, end);
        case MADV_DONTNEED:
                return madvise_dontneed(vma, prev, start, end);
        default:
-- 
2.9.3