On Tue 25-08-15 15:03:00, Eric B Munson wrote: [...]
Would you drop your objections to the VMA flag if I drop the portions of the patch that expose it to userspace?
The rework to not use the VMA flag is pretty sizeable and is much more ugly IMO. I know that you are not wild about using bit 30 of 32 for this, but perhaps we can settle on not exporting it to userspace so we can reclaim it if we really need it in the future?
Yes, that would be definitely more acceptable for me. I do understand that you are not wild about changing mremap behavior.
Anyway, I would really prefer if the vma flag was really used only at few places - when we are clearing it along with VM_LOCKED (which could be hidden in VM_LOCKED_CLEAR_MASK or something like that) and when we decide whether the populate or not (this should be __mm_populate). But maybe I am missing some call paths where gup is called unconditionally, I haven't checked that.