On Tue 12-05-20 14:41:46, Huang Ying wrote:
> To improve the code readability and get random number with higher
> quality.

I understand the readability argument but why should prandom_u32_max
(which I was not aware of) provide a higher quality randomness?

> Signed-off-by: "Huang, Ying" <ying.hu...@intel.com>
> Cc: 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>

To the change itself
Acked-by: Michal Hocko <mho...@suse.com>

> ---
>  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

-- 
Michal Hocko
SUSE Labs

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