On Thu, Jan 7, 2021 at 12:17 PM Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > I still think the real fix is "Don't do that then", and just take the > write lock. The alternative, of course, is to just make sure the page table flush is done inside the page table lock (and then we make COW do the copy inside of it). But this whole "we know UFFD breaks all rules, we'll add even more crap to it" approach is horrendous. Linus