Re: [PATCH RFC v2 2/2] mm: Rework swap handling of zap_pte_range

[John Hubbard]

On 11/15/21 05:57, Matthew Wilcox wrote:
> On Mon, Nov 15, 2021 at 09:49:51PM +0800, Peter Xu wrote:
> > Clean the code up by merging the device private/exclusive swap entry handling
> > with the rest, then we merge the pte clear operation too.
> >
> > struct* page is defined in multiple places in the function, move it upward.
>
> Is that actually a good thing?  There was a time when declaring

Yes. It is a very good thing. Having multiple cases of shadowed variables
(in this case I'm using programming language terminology, or what I
remember it as, anyway) provides lots of opportunities to create
hard-to-spot bugs.

> variables more locally helped compilers with liveness analysis and
> register allocation.  Compilers are probably smarter now.

...as long as the above checks out, and I see from Peter's response that
we're OK.


thanks,
--
John Hubbard
NVIDIA