Re: [RFC PATCH] kernel: sched: Provide a pointer to the valid CPU mask

[Peter Zijlstra]

On Tue, Apr 04, 2017 at 08:42:02PM +0200, Sebastian Andrzej Siewior wrote:
> While converting the existing users I tried to stick with the rules
> above howeverâ well mostly CPUFREQ tries to temporary switch the CPU
> mask to do something on a certain CPU and then switches the mask back it
> its original value.


There's a bunch of that through ancient and rotten parts of the kernel.
All those sites are broken.

Nothing stops userspace from setting a different affinity right after
the kernel does for those threads.