Re: [PATCH 3/3] c/r: define s390-specific checkpoint-restart code (v6)

[Nathan Lynch <ntl-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>]

On Wed, 25 Feb 2009 16:28:17 -0600
Nathan Lynch <ntl-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org> wrote:
> > +
> > +void cr_s390_mm(int op, struct cr_hdr_mm_context *hh, struct mm_struct *mm)
> > +{
> > +#if 0
> > +	/* Oren's v13 is on an older kernel which has no vdso_base
> > +	 * on newer kernel, we'll have to enable this
> > +	 */
> > +	CR_COPY(op, hh->vdso_base, mm->context.vdso_base);
> > +#endif
> 
> During restart, does this replace the current task's VDSO contents, and
> if so, is that wise?  VDSO areas contain things like timestamps for
> gettimeofday()...

Okay, it doesn't blow away the VDSO contents, it merely copies
the value of vdso_base (something I would have been able to discern more
quickly without the macro, btw).

But you'll still have to ensure that vdso region is installed at the
address that the restarting task expects -- see
arch/s390/kernel/vdso.c::arch_setup_additional_pages.