Yes, sampling data for the kernel can be viewed along with your application sampling data. The requirement, however, is that you have rebuilt your kernel with debug information (i.e., '-g' option on the gcc compiler). Once you have done this and collect data with this debug kernel, you can view statistics for the kernel modules and functions. Note: "debug" does not mean you have to disable optimization, only that debug symbols are generated for the kernel modules.
Also, just to make sure we're all on the same page here: we can't use callgraph on the linux kernel because the callgraph technology re-instruments the code you want to profile. The, during analysis, vtune launches that re-instrumented version of the code to collect data.
On Linux, you can't have two kernels running at once, of course, so that means sampling is the appropriate profiling technology to use when you're looking for kernel data.