On Mon, Feb 11, 2019 at 03:54:47PM -0700, Jason Gunthorpe wrote: > On Mon, Feb 11, 2019 at 05:44:32PM -0500, Daniel Jordan wrote: > > > All five of these places, and probably some of Davidlohr's conversions, > > probably want to be collapsed into a common helper in the core mm for > > accounting pinned pages. I tried, and there are several details that > > likely need discussion, so this can be done as a follow-on. > > I've wondered the same..
I'm really thinking this would be a nice way to ensure it gets cleaned up and does not happen again. Also, by moving it to the core we could better manage any user visible changes. >From a high level, pinned is a subset of locked so it seems like we need a 2 sets of helpers. try_increment_locked_vm(...) decrement_locked_vm(...) try_increment_pinned_vm(...) decrement_pinned_vm(...) Where try_increment_pinned_vm() also increments locked_vm... Of course this may end up reverting the improvement of Davidlohr Bueso's atomic work... :-( Furthermore it would seem better (although I don't know if at all possible) if this were accounted for in core calls which tracked them based on how the pages are being used so that drivers can't call try_increment_locked_vm() and then pin the pages... Thus getting the account wrong vs what actually happened. And then in the end we can go back to locked_vm being the value checked against RLIMIT_MEMLOCK. Ira