zsmalloc: consider ZS_ALMOST_FULL as migrate source

There is no reason to prevent select ZS_ALMOST_FULL as migration source
if we cannot find source from ZS_ALMOST_EMPTY.

With this patch, zs_can_compact will return more exact result.

Signed-off-by: Minchan Kim <minchan.kim@lge.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 615b9b9b45ebfd1f1db017b4ac06b811c52a7d2e..c10885ca87a49e05c30f2237fb8270a6a421d57a 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1691,11 +1691,17 @@ static enum fullness_group putback_zspage(struct zs_pool *pool,
 
 static struct page *isolate_source_page(struct size_class *class)
 {
-       struct page *page;
+       int i;
+       struct page *page = NULL;
+
+       for (i = ZS_ALMOST_EMPTY; i >= ZS_ALMOST_FULL; i--) {
+               page = class->fullness_list[i];
+               if (!page)
+                       continue;
 
-       page = class->fullness_list[ZS_ALMOST_EMPTY];
-       if (page)
-               remove_zspage(page, class, ZS_ALMOST_EMPTY);
+               remove_zspage(page, class, i);
+               break;
+       }
 
        return page;
 }
@@ -1711,9 +1717,6 @@ static unsigned long zs_can_compact(struct size_class *class)
 {
        unsigned long obj_wasted;
 
-       if (!zs_stat_get(class, CLASS_ALMOST_EMPTY))
-               return 0;
-
        obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) -
                zs_stat_get(class, OBJ_USED);