Re: [patch 01/15] mm/memory.c: avoid access flag update TLB flush for retried page fault

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, Jul 23, 2020 at 9:15 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
>         }
> +
> +       if ((vmf->flags & FAULT_FLAG_WRITE) && !(vmf->flags & FAULT_FLAG_TRIED))
> +               entry = pte_mkdirty(entry);
> +       else if (vmf->flags & FAULT_FLAG_TRIED)
> +               goto unlock;
> +

What? No.

Not even with the folded update do I want this.

The notion of "this is a retry, so let's do nothing" is fundamentally
wrong. It makes no sense.

It *may* make sense to say "ok, don't bother flushing the TLB if this
is a retry, because we already did that originally". MAYBE.

I'm dropping this patch as incomprehensible, with or without the
cleaned-up mversion.

                  Linus