On Thu, Jul 28, 2016 at 07:55:48AM +0200, Heiko Carstens wrote:

On Wed, Jul 27, 2016 at 11:46:01PM -0400, Theodore Ts'o wrote:

quoted

On Wed, Jul 27, 2016 at 09:14:00AM +0200, Heiko Carstens wrote:

quoted

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 ;)

Oh, I just realized that Linus pulled your changes. Actually I was hoping
we could get this fixed before the broken code would be merged.
Could you please make sure the bug fix gets included as soon as possible?

Right now booting a kernel with any defconfig on s390 will crash because of
this.

I will also change the fake NUMA code on s390, since it doesn't make sense
to have possible but not online nodes (in this case).

quoted

commit 59b8d4f1f5d26e4ca92172ff6dcd1492cdb39613
Author: Theodore Ts'o [off-list ref]
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 [off-list ref]
    Fixes: 1e7f583af67b ("random: make /dev/urandom scalable for silly userspace programs")
    Signed-off-by: Theodore Ts'o [off-list ref]

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;

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