[PATCHv4 5/6] zram: do not mark idle slots that cannot be idle

[Sergey Senozhatsky]

ZRAM_SAME slots cannot be post-processed (writeback or
recompress) so do not mark them ZRAM_IDLE.  Same with
ZRAM_WB slots, they cannot be ZRAM_IDLE because they
are not in zsmalloc pool anymore.

Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
 drivers/block/zram/zram_drv.c | 25 ++++++++++++++++++-------
 1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8ba994a5f30e..e48e2deec685 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -392,17 +392,28 @@ static void mark_idle(struct zram *zram, ktime_t cutoff)
 		/*
 		 * Do not mark ZRAM_UNDER_WB slot as ZRAM_IDLE to close race.
 		 * See the comment in writeback_store.
+		 *
+		 * Also do not mark ZRAM_SAME slots as ZRAM_IDLE, because no
+		 * post-processing (recompress, writeback) happens to the
+		 * ZRAM_SAME slot.
+		 *
+		 * And ZRAM_WB slots simply cannot be ZRAM_IDLE.
 		 */
 		zram_slot_lock(zram, index);
-		if (zram_allocated(zram, index) &&
-				!zram_test_flag(zram, index, ZRAM_UNDER_WB)) {
+		if (!zram_allocated(zram, index) ||
+		    zram_test_flag(zram, index, ZRAM_WB) ||
+		    zram_test_flag(zram, index, ZRAM_UNDER_WB) ||
+		    zram_test_flag(zram, index, ZRAM_SAME)) {
+			zram_slot_unlock(zram, index);
+			continue;
+		}
+
 #ifdef CONFIG_ZRAM_TRACK_ENTRY_ACTIME
-			is_idle = !cutoff || ktime_after(cutoff,
-							 zram->table[index].ac_time);
+		is_idle = !cutoff ||
+			ktime_after(cutoff, zram->table[index].ac_time);
 #endif
-			if (is_idle)
-				zram_set_flag(zram, index, ZRAM_IDLE);
-		}
+		if (is_idle)
+			zram_set_flag(zram, index, ZRAM_IDLE);
 		zram_slot_unlock(zram, index);
 	}
 }
-- 
2.46.0.598.g6f2099f65c-goog