On 06/29/2013 09:26 AM, Eric Dumazet wrote:> On Sat, 2013-06-29 at 09:11 -0700, Ben Greear wrote:
>
>> Do you know if your patch should go in 3.9?
>>
>
> Yes it should.
Ok, I''ll add that to my tree.
>> Your test case sounds a bit like what gives us the rare crash in
tcp_collapse
>> (we have lots of bouncing wifi interfaces running slow-speed TCP
trafic). But,
>> it takes days for us to hit the problem most of the time.
>
> Well, unfortunately that''s a different problem :(
For what it''s worth, I added this patch to my tree. We
haven''t hit the problem
since, but perhaps on the over-the-weekend run we''ll see it.
commit 0286716b36a0e5b82c385052a0971f44bc3c3442
Author: Ben Greear <greearb@candelatech.com>
Date: Tue Jun 25 15:49:52 2013 -0700
tcp: Try to work around crash in tcp_collapse.
And print out some info about why it crashed.
Signed-off-by: Ben Greear <greearb@candelatech.com>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a2f267a..63f7704 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4810,7 +4810,15 @@ restart:
int offset = start - TCP_SKB_CB(skb)->seq;
int size = TCP_SKB_CB(skb)->end_seq - start;
- BUG_ON(offset < 0);
+ if (WARN_ON(offset < 0)) {
+ /* We see a crash here (when using BUG_ON) every
few days under
+ * some torture tests. I''m not sure
how to clean this up properly,
+ * so just return and hope thinks keep muddling
through. --Ben
+ */
+ printk("offset: %i start: %i seq: %i size:
%i copy: %i\n",
+ offset, start, TCP_SKB_CB(skb)->seq,
size, copy);
+ return;
+ }
if (size > 0) {
size = min(copy, size);
if (skb_copy_bits(skb, offset, skb_put(nskb,
size), size))
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com