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SubjectRe: [BUG] 2.5.65: Caching MSR_IA32_SYSENTER_CS kills dosemu

On 1 Apr 2003, Robert Love wrote:
>
> Actually, do they do disable preemption - if they do not, something is
> broken.

Ok, I was too lazy to check. Anyway, the test-patch is worth trying, since
one of the areas fixed had no pre-emption protection regardless (ie it
used just a plain "smp_processor_id()"), and the patch should be
technically equivalent (just uglier) to a proper get_cpu().

> Because, even on UP, preemption can lead to a race over a variable that
> has no locking because its per-CPU. But it would need locking
> otherwise, and thus we do need to disable preemption.

Yes, that was certainly the case here.

Linus

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