Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late()

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late()
Date	2015-09-22 20:00 +0200
Message-ID	<qbA1f-46k-77@gated-at.bofh.it> (permalink)
References	<qbpfr-5Ff-1@gated-at.bofh.it> <qbpfr-5Ff-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, Sep 21, 2015 at 11:23 PM, Ingo Molnar <mingo@kernel.org> wrote:
> Add a late PGD init callback to places that allocate a new MM
> with a new PGD: copy_process() and exec().
>
> The purpose of this callback is to allow architectures to implement
> lockless initialization of task PGDs, to remove the scalability
> limit of pgd_list/pgd_lock.

Do we really need this?

Can't we just initialize the pgd when we allocate it, knowing that
it's not in sync, but just depend on the vmalloc fault to add in any
kernel entries that we might have missed?

I liked the other patches in the series because they remove code and
simplify things. This patch I don't like.

There may be some reason we need it that I missed, and which makes me
go "Duh!" when you tell me. But please do tell me.

               Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 20:00 +0200
  Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Andy Lutomirski <luto@amacapital.net> - 2015-09-22 20:10 +0200
    Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 20:30 +0200
      Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Andy Lutomirski <luto@amacapital.net> - 2015-09-22 20:40 +0200
        Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-22 20:50 +0200
          Re: [PATCH 05/11] mm: Introduce arch_pgd_init_late() Andy Lutomirski <luto@amacapital.net> - 2015-09-22 21:00 +0200

csiph-web