Thread (7 messages) 7 messages, 4 authors, 2016-07-28

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

From: Heiko Carstens <hidden>
Date: 2016-07-28 05:56:03
Also in: linux-mm, lkml

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:
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 ;)
quoted hunk ↗ jump to hunk
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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