Fortify the protection against the use of an invalid/corrupted
CONFIG_SLAB kmem_cache per-cpu array_cache.limit value during
session initialization.  In a recently seen vmcore, several of the
array_cache.limit values were corrupted such that they were stored
as negative values, which in turn caused the "kmem -[sS]" options
to fail immediately with a dump of the internal memory buffer
allocation statistics and the error message "kmem: cannot allocate
any more memory!".
(anderson@redhat.com)