On Tue, 2016-09-27 at 02:11 +0300, Kirill A. Shutemov wrote:
> On Mon, Sep 26, 2016 at 05:23:29PM -0400, Rik van Riel wrote:
> > 
> > On Mon, 2016-09-26 at 13:58 -0700, Linus Torvalds wrote:
> > 
> > > 
> > > Is there really any reason for that incredible indirection? Do we
> > > really want to make the page_waitqueue() be a per-zone thing at
> > > all?
> > > Especially since all those wait-queues won't even be *used*
> > > unless
> > > there is actual IO going on and people are really getting into
> > > contention on the page lock.. Why isn't the page_waitqueue() just
> > > one
> > > statically sized array?
> > 
> > Why are we touching file pages at all during fork()?
> 
> We are not.
> Unless the vma has private pages (vma->anon_vma is not NULL).
> 
> See first lines for copy_page_range().

Ahhh, indeed. I thought I remembered an optimization like
that.

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