On 15/05/18 14:47, Peter Zijlstra wrote: > On Tue, May 15, 2018 at 01:43:23PM +0300, Boaz Harrosh wrote: >> Yes I know, but that is exactly the point of this flag. I know that this >> address is only ever accessed from a single core. Because it is an mmap (vma) >> of an O_TMPFILE-exclusive file created in a core-pinned thread and I allow >> only that thread any kind of access to this vma. Both the filehandle and the >> mmaped pointer are kept on the thread stack and have no access from outside. >> >> So the all point of this flag is the kernel driver telling mm that this >> address is enforced to only be accessed from one core-pinned thread. > > What happens when the userspace part -- there is one, right, how else do > you get an mm to stick a vma in -- simply does a full address range > probe scan? > > Something like this really needs a far more detailed Changelog that > explains how its to be used and how it is impossible to abuse. Esp. that > latter is _very_ important. > Thank you yes. I will try and capture all this thread in the commit message and as Christoph demanded supply a user code to demonstrate usage. Thank you for looking Boaz
