[OpenAFS-devel] Linux client 2.6.38 and above hangs

[Simon Wilkinson]

On 30 Apr 2011, at 23:52, Russ Allbery wrote:

> Markus Suvanto <markus.suvanto@gmail.com> writes:
>=20
>> Openafs client (openafs-stable-1_4_x, openafs-stable-1_6_x and master
>> branch) hangs if linux kernel is 2.6.38 or newer. The openafs kernel
>> module compiles and client stars OK but computer totally hangs if I =
try
>> to compile linux kernel under /afs/path/to/kernel-2.6
>=20
> This is probably the same problem that we've been trying to track down
> elsewhere.  Do you get a soft CPU lockup warning from the kernel after
> about a minute waiting for the system to recover?

What we're interested in seeing here is the first stacktrace that the =
soft lookup warning generates. Subsequent stacktraces tend to be less =
interesting, as they are often corrupt. To assist with this it's =
possible to run

sysctl kernel.softlookup_panic=3D1

to make the machine panic as soon as a soft lookup appears. To capture =
the output from this, you will either need a serial console, or a "real" =
console with X and screen blanking disabled, and a handy digital camera.=20=


Markus: Are you also on a Debian system?
Russ/Markus: Do you have SELinux disabled on your systems?

One possibility is that this is being caused by the new RCU dcache =
support, which is disabled if the machine is running SELinux. That would =
explain why Marc and I on Fedora (with SELinux enabled by default) are =
unable to reproduce the problem.

Cheers,

Simon.