Michael Kerrisk found a bug in the shm accounting code: sysv shm allows to
create SHMMNI+1 shared memory segments, instead of SHMMNI segments.  The +1
is probably from the first shared anonymous mapping implementation that
used the sysv code to implement shared anon mappings.

The implementation got replaced, it's now the other way around (sysv uses
the shared anon code), but the +1 remained.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>