On Thu, Jan 7, 2021 at 12:04 PM Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote: > > However there are two cases that could wrprotecting exclusive anon > pages with only the mmap_read_lock: I still think the real fix is "Don't do that then", and just take the write lock. The UFFDIO_WRITEPROTECT case simply isn't that critical. It's not a normal operation. Same goes for softdirty. Why have those become _so_ magical that they can break the VM for everybody else? Linus