Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev
Date	2017-07-03 18:40 +0200
Message-ID	<tZcye-40A-33@gated-at.bofh.it> (permalink)
References	(2 earlier) <tY49H-61M-5@gated-at.bofh.it> <tY7AC-8dL-27@gated-at.bofh.it> <tY7TY-8jY-11@gated-at.bofh.it> <tY8dj-8qS-13@gated-at.bofh.it> <tZbLQ-3s5-17@gated-at.bofh.it>
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On Mon, Jul 3, 2017 at 8:49 AM, Michal Hocko <mhocko@kernel.org> wrote:
>
> If you think this is worth pursuing in upstream, just let me know and I
> can polish it, add a patch for the man page and other things.

Hmm. This doesn't look bad, except the bprm games there really look annoying.

Also, I'm wondering whether this should be per-thread - conceptually
"expand_stack()" really is a thread thing. All callers are using
"current", although it's not always obvious.

So I'm wondering if a slightly larger patch that simply made the
"limit" be an _argument_ to expand_stack() would clean up both of
these issues. The execve() use would simply pass in the stack limit,
and the fault users would pass in "current->expand_stack_limit".

Again, I'm not sure how many people really use multiple GROW_DOWN
stacks for threading, but it's conceptually the right thing to do, so
I think conceptually this should be per-thread. And the fact that it
might clean up the execve() thing makes me think it's the right thing
to do.

What do you think?

                 Linus

Thread

[PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Oleg Nesterov <oleg@redhat.com> - 2017-06-28 20:00 +0200
  Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-29 01:30 +0200
    Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Oleg Nesterov <oleg@redhat.com> - 2017-06-29 17:20 +0200
      Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-29 20:30 +0200
        Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Oleg Nesterov <oleg@redhat.com> - 2017-06-29 21:00 +0200
          Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-29 21:10 +0200
    Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Michal Hocko <mhocko@kernel.org> - 2017-06-30 15:30 +0200
      Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-30 19:10 +0200
        Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Michal Hocko <mhocko@kernel.org> - 2017-06-30 19:30 +0200
          Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-06-30 19:50 +0200
            Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Michal Hocko <mhocko@kernel.org> - 2017-07-03 17:50 +0200
              Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Linus Torvalds <torvalds@linux-foundation.org> - 2017-07-03 18:40 +0200
                Re: [PATCH 0/1] expand_downwards: don't require the gap if !vm_prev Michal Hocko <mhocko@kernel.org> - 2017-07-03 19:00 +0200

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