Re: v3.0-rc* intermittent network failure: Test case found!

On 21/07/11 16:18, Richard Kennedy wrote:

quoted

Richard Kennedy[off-list ref]  :

quoted

I keep seeing a total network failure on v3.0.0-rc* , it is highly
intermittent, anything from 1 hour to 12+, and I don't have a reliable
test case.
When it fails I lose all network comms, but there are no errors in the
system log, no hung tasks reported, nothing. But after it fails the
machine hangs during shutdown, it just never turns off. So I guess
something is getting stuck but I can't find it.

I have found a reliable test case, I can instantly trigger my problem by 
starting 2 instances of rsync at the same time. [this is on x86_64 AMDX2]

e.g.
rsync -a linux-2.6 server:t1 & ;rsync -a linux-2.6 server:t2 &


If I have a ping running when I trigger the problem, it pauses then 
errors with :-

	ping: sendmsg: No buffer space available

But if I start a ping after, it fails with

...	Destination Host Unreachable
.

I have a serial console attached but don't really understand what it's 
telling me.
AFAICT -- I have no blocked tasks  - sysrq w shows :-


SysRq : Show Blocked State
   task                        PC stack   pid father
Sched Debug Version: v0.10, 3.0.0 #46
ktime                                   : 7129717.783042
sched_clk                               : 7126380.221722
cpu_clk                                 : 7129711.544071
jiffies                                 : 4301797008
sched_clock_stable                      : 0
.....[lots more schedule & cpu info]

But now I've got a reliable test case I can find a last know good kernel 
and have a stab at bisecting this, unless anyone has got any better 
suggestions?

regards
Richard