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

Heiko Carstens
2016-07-28T05:56:03Z

On Wed, Jul 27, 2016 at 11:46:01PM -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?
>
> - Ted

Yes, it does. It's actually the same what I did to fix this ;)

> commit 59b8d4f1f5d26e4ca92172ff6dcd1492cdb39613
> Author: Theodore Ts'o <tytso@mit.edu>
> Date: Wed Jul 27 23:30:25 2016 -0400
>
> random: use for_each_online_node() to iterate over NUMA nodes
>
> This fixes a crash on s390 with fake NUMA enabled.
>
> Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
> Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly userspace programs")
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 8d0af74..7f06224 100644
> --- 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);
> - 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;
>