On Fri, 2012-06-29 at 07:57 +1000, Benjamin Herrenschmidt wrote:

On Thu, 2012-06-28 at 18:52 +0200, Peter Zijlstra wrote:

quoted

No I think you're right (as always).. also an IPI will not force
schedule the thread that might be running on the receiving cpu, also
we'd have to wait for any such schedule to complete in order to
guarantee the mm isn't lazily used anymore.

Bugger.. 

You can still do it if the mm count is 1 no ? Ie, current is the last
holder of a reference to the mm struct... which will probably be the
common case for short lived programs.

Also I just remembered... x86 flushes in SMP via IPIs right ? So maybe
you can invent a "detach and flush" variant of it ? 

Cheers,
Ben.


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