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SubjectRe: [patch] sched: unlocked context-switches

* David Mosberger <davidm@napali.hpl.hp.com> wrote:

> Now, Ingo says that the order is reversed with his patch, i.e.,
> switch_mm() happens after switch_to(). That means flush_tlb_mm() may
> now see a current->active_mm which hasn't really been activated yet.
> That should be OK since it would just mean that we'd do an early (and
> duplicate) activate_context(). While it does not give me a warm and
> fuzzy feeling to have this inconsistent state be observable by
> interrupt-handlers (and, in particular, IPI-handlers), I don't see any
> problem with it off hand.

thanks for the analysis. I fundamentally dont have any fuzzy feeling
from having _any_ portion of the context-switch path nonatomic, but with
more complex hardware it's just not possible it seems.

Ingo
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