Thread (28 messages) 28 messages, 7 authors, 2012-02-08

Re: infinite spin in RT when booting with DHCP on

From: Tim Sander <hidden>
Date: 2012-02-02 23:44:25

Hi Guys

Am Donnerstag 02 Februar 2012, 22:34:26 schrieb Steven Rostedt:
On Thu, 2012-02-02 at 21:13 +0100, Uwe Kleine-König wrote:
quoted
enabled the ksoftirq is also running wild with 3.0-rt. This also happens
when I fail to reproduce that on a pcm043 machine using 3.0.18-rt34. Can
you provide me your config. Does the problem occur on every boot for
you? If not, how often do I need to reboot?
Note, you also said (on IRC) that you boot off this card via NFS root.
I'm not sure Tim has the same setup, and that may be a big difference in
how this bug comes about.

It's a race issue, and it may require enabling the network interface
after the system is up and running.
Its indeed a race and it is most of the time only triggered when ubifs is 
attached or the ubifs worker thread is active in background. The error must be 
there sleeping for at least 2.6.31. We where using 2.6.33-rt (if i remember 
correctly) and it might occoured once but i wasn't sure back then. Which lead 
me to the complete wrong direction that ubi was at fault. The bug occurs only 
very seldom with static ip addresses configured. So dhcp is needed to 
reproduce this bug more easily. Then i found out that connman is a good way to 
trigger this bug. So to trigger i started dhclient, connman and if it didn't 
show up i did some "ifconfig eth0 up/down" poking. But the first time i had 
the hw debugger wired it didn't show up for some reason even when i was trying 
to trigger it for an hour or so.

@Uwe: I am currently at home and its to late to fire my work computer up. 
You'll get the kconfig tomorrow... ahm later.
I will then also test the patch of Steve if i manage that before leaving to 
FOSDEM :-).

Best regards
Tim
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