[CRIU] Re: [PATCH cr] mm: taking into account a gurad page to find a space for a restorer vma

[Cyrill Gorcunov]

On Mon, Sep 10, 2012 at 02:18:45PM +0400, Andrey Wagin wrote:
> 2012/9/10 Pavel Emelyanov <xemul at parallels.com>:
> > On 09/10/2012 12:07 PM, Andrey Vagin wrote:
> >>
> >> Actually a gurad page is a part of a stack vma and we don't want to remap
> >> it by a restorer vma.
> >>
> >> Signed-off-by: Andrey Vagin <avagin at openvz.org>
> >> ---
> >>  restorer.c |    7 -------
> >>  util.c     |    6 ++++++
> >>  2 files changed, 6 insertions(+), 7 deletions(-)
> >>
> >
> > Plz, describe the problem you're solving.
> 
> crtools on restore finds a place for a restorer vma, which will not
> intersect with other VMAs. A guard page is a part of a stack VMA, if
> we don't take into account it, we can place the restorer VMA on it and
> that case is a bug.

Wait, it seems I was rushing with my ack ;) Look, if we start substracting
guard page at dumping time -- what we will have after a couple of c/r cycles?
Would not this lead to situation where we expand stack manually? Every new
c/r cycle add one page to the bottom of stack, no?

	Cyrill