zram: free secondary algorithms names

We need to kfree() secondary algorithms names when reset zram device that
had multi-streams, otherwise we leak memory.

[[email protected]: kfree(NULL) is legal]
  Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 001d927357 ("zram: add recompression algorithm sysfs knob")
Signed-off-by: Sergey Senozhatsky <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

drivers/block/zram/zram_drv.c

@@ -2112,6 +2112,11 @@ static void zram_destroy_comps(struct zram *zram)
 		zram->num_active_comps--;
 	}
 
+	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {
+		kfree(zram->comp_algs[prio]);
+		zram->comp_algs[prio] = NULL;
+	}
+
 	zram_comp_params_reset(zram);
 }