[CRIU] [PATCH] proc_parse: Borrow vmi iif there is file referenced

[Cyrill Gorcunov]

On Thu, Mar 06, 2014 at 07:27:19PM +0400, Pavel Emelyanov wrote:
> On 03/06/2014 06:02 PM, Cyrill Gorcunov wrote:
> > On Thu, Mar 06, 2014 at 04:51:38PM +0400, Pavel Emelyanov wrote:
> >>
> >> Hm... Can we do it like this
> >>
> >> if (prev->vm_file_fd < 0)
> >> 	return 0;
> >>
> >> Since for anonymous mappings dev:ino would be 0:0 (matching) and we don't
> >> even need to try messing the map_files -- it will be absent for sure.
> > 
> > Like this?
> > 
> 
> Not exactly (I withdraw the previous comment).
> 
> > @@ -172,6 +172,13 @@ static int vma_get_mapfile(struct vma_area *vma, DIR *mfd,
> >  	if (prev_vfi->vma && vfi_equal(vfi, prev_vfi)) {
> >  		struct vma_area *prev = prev_vfi->vma;
> >  
> > +		/*
> > +		 * If vfi is equal (!) and negative @vm_file_fd --
> > +		 * we have nothing to borrow for sure.
> > +		 */
> > +		if (prev->vm_file_fd < 0)
> 
> The vma->vm_file_id = -1; should be here. Otherwise it's 0 and the rest
> of criu code thinks it's a file descriptor 0 :)

How it gets 0 here? alloc_vma_area sets it to -1 then this area become a previous
one and the next call to vma_get_mapfile simply exit with 0 without
modifying this member. I seem to get confused.