On Wed, 2013-07-10 at 12:33 +0200, Alexander Graf wrote:

It's not exactly obvious that you're calling it with writing == 1 :).
Can you create a new local variable "is_write" in the calling
function, set that to 1 before the call to get_user_pages_fast and
pass it in instead of the 1? The compiler should easily optimize all
of that away, but it makes the code by far easier to read.

Ugh ?

Nobody else does that .... (look at futex :-)

Ben.