Re: [BUG -next] "random: make /dev/urandom scalable for silly userspace programs" causes crash

Joe Perches
2016-07-28T18:12:22Z

On Wed, 2016-07-27 at 23:46 -0400, Theodore Ts'o wrote:
> On Wed, Jul 27, 2016 at 09:14:00AM +0200, Heiko Carstens wrote:
> >
> > it looks like your patch "random: make /dev/urandom scalable for silly
> > userspace programs" within linux-next seems to be a bit broken:
> >
> > It causes this allocation failure and subsequent crash on s390 with fake
> > NUMA enabled
> Thanks for reporting this.  This patch fixes things for you, yes?

trivia:

> diff --git a/drivers/char/random.c b/drivers/char/random.c
[]
> @@ -1668,13 +1668,12 @@ static int rand_initialize(void)
>  #ifdef CONFIG_NUMA
>   pool = kmalloc(num_nodes * sizeof(void *),
>          GFP_KERNEL|__GFP_NOFAIL|__GFP_ZERO);

The __GFP_ZERO is unusual and this could use kcalloc instead.

> - for (i=0; i < num_nodes; i++) {
> + for_each_online_node(i) {
>   crng = kmalloc_node(sizeof(struct crng_state),
>       GFP_KERNEL | __GFP_NOFAIL, i);
>   spin_lock_init(&crng->lock);
>   crng_initialize(crng);
>   pool[i] = crng;
> -
>   }
>   mb();
>   crng_node_pool = pool;