[CRIU] Dealing with VDSO remap

[Cyrill Gorcunov]

On Thu, Mar 19, 2015 at 06:28:24PM +0300, Pavel Emelyanov wrote:
> On 03/06/2015 05:15 PM, Laurent Dufour wrote:
> 
> > If not, is there a plan in the CRIU project to to deal with that, other
> > than by hacking the kernel to update its reference at restart time ?
> 
> BTW, I've just remembered that there's a way to overcome this issue
> by mapping a fake VDSO into task which would contain plan calls to
> the respective system calls.
> 
> It's not perfect solution, but I think it can be used as temporary
> one until the VDSO remapping is resolved in the kernel.
> 
> What do you think?

If I understand correctly the problem is not in the vDSO as its
own but rather an addressing problem. If on restore the base
vdso address differs from one saved in image and the kernel
still carry a reference to the former vdso, we might get a
situation where memory map from image get intersected with
vdso address kernel keeps in own guts, so nothing would help
here until the kernel patched.