The failing kernel virtual addresses are 8015564b and 804b1210, so apparently
you're running a kernel configured with a 2G/2G split? I'm not sure
whether the crash utility even works with that configuration? Crash does
support the old RHEL4 "hugemem" 4G/4G kernels, but I've never worked with
a 2G/2G kernel. In any case, it may work by dumb luck -- to be sure, first
try to run crash on the live system.
Anyway, even though the dump header advertises a kernel configured with
the traditional 3G/1G split (with kernel memory starting at c000000),
that "dh_memory_start" field is not used by the crash utility.
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