On Tue, Aug 14, 2012 at 05:11:13PM -0300, Rafael Aquini wrote:

On Tue, Aug 14, 2012 at 10:51:39PM +0300, Michael S. Tsirkin wrote:

quoted

What I think you should do is use rcu for access.
And here sync rcu before freeing.
Maybe an overkill but at least a documented synchronization
primitive, and it is very light weight.

I liked your suggestion on barriers, as well.

Rik, Mel ?

Further instead of simple assignment I would add an api
in mm to set/clear the balloon mapping, with proper locking.

This could fail if already set, and thus fix crash with
many ballons.