On Fri, Apr 11, 2014 at 05:32:49PM +0200, Peter Zijlstra wrote:
On Fri, Apr 11, 2014 at 05:22:07PM +0200, Oleg Nesterov wrote:
And I am just curious, why arm's copy_to_user_page() disables premption before memcpy?
Without looking, I suspect its because the VIVT caches, they need to get shot down on every context switch.
So... let's think about that for a moment... if we have a preemption event, then that's a context switch, which means...
No, this is obviously not the reason, because such an event on a fully VIVT system would result in the caches being flushed, meaning that we wouldn't need to do anything if we could be predicably preempted at that point.