Re: 2.6.9 rc2 freezing

Dave Jones
2004-09-15T17:06:41Z

On Wed, Sep 15, 2004 at 12:06:48PM -0400, Lee Revell wrote:

> Anyway, if you are running anything on your server that breaks under
> PREEMPT, it will break anyway as soon as you add another processor.

Wrong. Code can be SMP safe but not preempt safe.
This is why we have get_cpu()/put_cpu(), and
preempt_disable()/preempt_enable() pairs around certain parts of code.

Anything using per-CPU data like MSRs for example needs explicit
protection against preemption.

Dave