2.4.18-xfs and the preemptive patch

I just installed the preemptive ( http://www.tech9.net/rml/linux/ ---- preempt-kernel-rml-2.4.18-4 ) patch on my 2.4.18-xfs tree and when i run this kernel, every process ends with "exited with preempt_count 1" ( for example "rc.2[35] exited with preempt_count 1" ) The number varies from 1 to 41 so far.
Is this a known issue that there is a fix to, or is it just a misconfigured syslog?

Please CC the answer to me as i don't subscribe to the mailing list.

//niklas
[email protected]

That message is caused by tasks exiting with a nonzero preempt_count. The preempt_count is basically a count of the number of spinlocks held, so it should always be zero when a task exits. Since it is positive, you don't have anything to worry about wrt "stability" but the system may not be preempting at all, which would make the preempt-kernel patch worthless.

I talked to Steve Lord and Eric Sandeen at SGI and they believe they know the cause of the problem. Basically, XFS destroys some data structures and doesn't unlock the associated lock, but just forgets about it. This is not good for kernel preemption.

They think the newest XFS in CVS does not do this anymore, but it still may in some places. Can you give it a try and let me know if you still see the messages? Especially with the same regularity and value.

http://oss.sgi.com/projects/xfs/cvs_download.html

Thanks,

Robert Love