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SubjectRe: [PATCH] protect migration/%d etc from sched_setaffinity
> On Thu, 2003-07-31 at 15:46, Joe Korty wrote:
>
> > Lock out users from changing the cpu affinity of those per-cpu system
> > daemons which cannot survive such a change, such as migration/%d.
> >
> > Passes basic handtest of sched_setaffinity(2) on various locked and
> > unlocked processes on a i386, otherwise untested except by eyeball.
> >
> > Except for one line in i386, no arch needed any changes to support
> > this patch.
>
> I have been wondering what to do about processor affinity and kernel
> threads. I just concluded "only root can change it, and we can let root
> stab herself if she really wants to."
>
> But if this is really an issue, why not just do:
>
> ret = -EINVAL;
> if (!p->mm)
> goto out_unlock;
>
> in sys_sched_setaffinity ?
>
> Robert Love


It's not all system daemons, just some of them that need protection.

Keeping the set of locked-down daemons to the smallest possible is
important when one wants to 'set aside' cpus for use only by
specific, need-the-lowest-latency-possible realtime applications.

Joe
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