[PATCH -V2] mm, swap: Use prandom_u32_max()

[Huang Ying]

To improve the code readability and take advantage of the common
implementation.

Signed-off-by: "Huang, Ying" <ying.hu...@intel.com>
Acked-by: Michal Hocko <mho...@suse.com>
Cc: Minchan Kim <minc...@kernel.org>
Cc: Tim Chen <tim.c.c...@linux.intel.com>
Cc: Hugh Dickins <hu...@google.com>
---

Changelog:

v2:

- Revise the patch description per Michal's comments.

---
 mm/swapfile.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/swapfile.c b/mm/swapfile.c
index a0a123e59ce6..2ec8b21201d6 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3220,7 +3220,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, 
int, swap_flags)
                 * select a random position to start with to help wear leveling
                 * SSD
                 */
-               p->cluster_next = 1 + (prandom_u32() % p->highest_bit);
+               p->cluster_next = 1 + prandom_u32_max(p->highest_bit);
                nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
 
                cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info),
-- 
2.26.2