Temporarily work around a race in the kernel. The kernel does a sanity check

Temporarily work around a race in the kernel.  The kernel does a sanity check
on the KVM memory range read via /dev/[k]mem.  However, if the user buffer
takes a VM fault and blocks the process, the related kernel memory could
become invalid while the process was blocked.  Try to avoid taking faults on
the user buffer by touching it first.

Reported-by: =?ISO-8859-1?Q?Stefan_Kr=FCger?= <skrueger@meinberlikomm.de>