On Tue, Jul 05, 2022 at 01:29:59PM -0300, Jason Gunthorpe wrote: > > Making the entire area given by the device to the p2p allocator available > > to user space seems sensible to me. That is what the current series does, > > and what a sysfs interface would do as well. > > That makes openning the mmap exclusive with the in-kernel allocator - > so it means opening the mmap fails if something else is using a P2P > page and once the mmap is open all kernel side P2P allocations will > fail? No. Just as in the current patchset you can mmap the file and will get len / PAGE_SIZE pages from the per-device p2pdma pool, or the mmap will fail if none are available. A kernel consumer (or multiple) can use other pages in the pool at the same time.
