linux-kernel - Re: [PATCH 2/2] mm: adds NOSIGBUS extension for out-of-band shmem read

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Date:   Tue, 1 Jun 2021 19:13:24 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
cc:     Ming Lin <mlin@...nel.org>, Hugh Dickins <hughd@...gle.com>,
        Simon Ser <contact@...rsion.fr>, Linux-MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mm: adds NOSIGBUS extension for out-of-band shmem
 read

On Tue, 1 Jun 2021, Linus Torvalds wrote:

> This series passes my "looks fine, is simple and straightforward" test.

I'm sorry, but it also passes my "hack that we do not want in shmem.c"
test. I'll say more in response to the preceding mail.

Hugh

> 
> One nit:
> 
> On Tue, Jun 1, 2021 at 1:22 PM Ming Lin <mlin@...nel.org> wrote:
> >
> > +               error = vm_insert_page(vma, (unsigned long)vmf->address,
> > +                                       ZERO_PAGE(0));
> 
> On architectures where this matters - bad virtual caches - it would be
> better to use ZERO_PAGE(vmf->address).
> 
> It doesn't make a difference on any sane architecture, but it's the
> RightThing(tm) to do.
> 
>             Linus
>