: [CRIU] [PATCH] restorer: Make sure the protection on code/data mm areas do fit the kernel requirements

[Cyrill Gorcunov]

On Fri, Apr 13, 2012 at 06:59:25PM +0400, Pavel Emelyanov wrote:
> > +	sys_mmap((void *)args->mm.mm_start_code, PAGE_SIZE, prot, flags, -1, 0);
> > +	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_START_CODE, (long)args->mm.mm_start_code, 0);
> > +	sys_munmap((void *)args->mm.mm_start_code, PAGE_SIZE);
> > +
> > +	sys_mmap((void *)args->mm.mm_end_code, PAGE_SIZE, PROT_EXEC | PROT_READ, flags, -1, 0);
> > +	ret |= sys_prctl_safe(PR_SET_MM, PR_SET_MM_END_CODE, (long)args->mm.mm_end_code, 0);
> > +	sys_munmap((void *)args->mm.mm_end_code, PAGE_SIZE);
> 
> 
> This is much nicer. Can we tune this a little bit more, i.e. like this
> 
> sys_mmap(code_start, code_end - code_start, ...)
> sys_prctl(PR_SET_MM_START_CODE)
> sys_prctl(PR_SET_MM_END_CODE)
> sys_munmap()
> 
> i.e. mmap only one mapping per PR_SET_MM, not two?

I tried this, but it not always work, because .text and
.data VMAs can cover really big space and we fail. Ie
it will work sometimes, sometimes it'll fail. Better to
stick with one which work always ;)

> And yes, talk to HPA in order to relax kernel's part of this.

Sure, I think this requiremen is not needed at all.

	Cyrill