Re: [PATCH v5 1/3] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity()

[Peter Zijlstra]

On Tue, Aug 16, 2022 at 03:27:32PM -0400, Waiman Long wrote:

> This will be some changes in behavior for arm64 systems with asymmetric
> CPUs in some corner cases. For instance, if sched_setaffinity()
> has never been called and there is a cpuset change before
> relax_compatible_cpus_allowed_ptr() is called, its subsequent call will
> follow what the cpuset allows but not what the previous cpu affinity
> setting allows.

That's arguably a correctness fix, no? That is, the save/restore should
not have been allowed to revert to an earlier cpuset state.