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>

1 files changed, 10 insertions, 7 deletions

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 615b9b9b45eb..c10885ca87a4 100644
--- 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);