On Thu, Sep 17, 2020 at 3:09 PM Jason Gunthorpe <jgg@xxxxxxxx> wrote: > > My advice for this -rc fix is to go with a single bit in the mm_struct > set on any call to pin_user_pages* Ack, except make sure it's a byte rather than a bitfield that could have races. Or even just a separate atomic_t. Keep it simple ans stupid and obvious. As you say, we can aim for cleanups later, make it obvious and reliable right now. Linus