Re: [patch] sched: unlocked context-switches

[Ingo Molnar <mingo@elte.hu>]

* 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