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

Theodore Ts'o
2016-07-28T03:46:11Z

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

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;