On Tue, Jun 22, 2021 at 11:28:30AM -0700, Linus Torvalds wrote: > On Tue, Jun 22, 2021 at 11:23 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > > > It wouldn't be _that_ bad necessarily. filemap_fault: > > It's not actually the mm code that is the biggest problem. We > obviously already have readahead support. > > It's the *fault* side. > > In particular, since the fault would return without actually filling > in the page table entry (because the page isn't ready yet, and you > cannot expose it to other threads!), you also have to jump over the > instruction that caused this all. Oh, I was assuming that it'd be a function call like get_user_pages_fast(), not an instruction that was specially marked to be jumped over. Gag reflex diminishing now?
