On Mon, Sep 14, 2020 at 3:55 PM Jason Gunthorpe <j...@nvidia.com> wrote: > > Just as an aside, the RDMA stuff is also supposed to set MADV_DONTFORK > on these regions, so I'm a bit puzzled what is happening here.
Did the fork perhaps happen _before_ , so the pages are shared when you do the pin? MADV_DONTFORK doesn't mean COW doesn't happen. It just means that the next fork() won't be copying that memory area. That said, it's possible that the test cases do something invalid - or maybe we've broken MADV_DONTFORK - and it all just happened to work before. So it's possible the breakage is exposing some other bug.. Linus