[PATCH v2] zsmalloc: consider ZS_ALMOST_FULL as migrate source

[Minchan Kim <minchan@kernel.org>]

From: Minchan Kim <minchan.kim@lge.com>

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.

* From v1
  * remove unnecessary found variable - Sergey

Signed-off-by: Minchan Kim <minchan.kim@lge.com>
---
 mm/zsmalloc.c |   17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 8c78bcb..9012645 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1686,11 +1686,17 @@ 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;
 }
@@ -1706,9 +1712,6 @@ 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);
 
-- 
1.7.9.5

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