[PATCH 1/2] mm: Allow architectures to request 'old' entries when prefaulting

Linus Torvalds torvalds at linux-foundation.org
Fri Dec 18 13:56:55 EST 2020

On Fri, Dec 18, 2020 at 3:04 AM Kirill A. Shutemov <kirill at shutemov.name> wrote:
> This should do. See below.

Looks fine.

> > Then that second loop very naturally becomes a "do { } while ()" one.
> I don't see it. I haven't found a reasonable way to rework it do-while.

Now that you return early for the "HEAD == NULL" case, this loop:

        for (; head; head = xas_next_entry(&xas, end_pgoff)) {

very naturally becomes

        do {
        } while ((head = xas_next_entry(&xas, end_pgoff)) != NULL);

because the initial test for 'head' being NULL is no longer needed,
and thus it's a lot more logical to just test it at the end of the
loop when we update it.


Maybe I'm missing something silly.


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