proc/smaps: show amount of nonlinear ptes in vma

proc/smaps: show amount of nonlinear ptes in vma

Currently, nonlinear mappings can not be distinguished from ordinary
mappings.  This patch adds into /proc/pid/smaps line "Nonlinear: <size>
kB", where size is amount of nonlinear ptes in vma, this line appears only
if VM_NONLINEAR is set.  This information may be useful not only for
checkpoint/restore project.

Requested by Pavel Emelyanov.

Signed-off-by: Konstantin Khlebnikov <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>