/sbin/init refuses to start with large physmem installed

Hi.

The box I have observed such a problem has 458752 MB of real memory (RAM).
With this high value /sbin/init refuses to start with "Out of memory".
I suspect there may be sort of (type) overflow somewhere.
A corresponding part of console output below:

start_init: trying /sbin/init

Cannot map anonymous memory(null): Out of memory: Cannot map anonymous
memoryCannot allocate memory
Enter full pathname of shell or RETURN for /bin/sh:
Cannot map anonymous memory(null): Out of memory: Cannot map anonymous
memoryCannot allocate memory
Cannot map anonymous memory(null): Out of memory: Cannot map anonymous
memoryCannot allocate memory
Enter full pathname of shell or RETURN for /bin/sh: ^CCannot map
anonymous memory(null): Out of memory: Cannot map anonymous
memoryCannot allocate memory
Cannot map anonymous memory(null): Out of memory: Cannot map anonymous
memoryCannot allocate memory
Enter full pathname of shell or RETURN for /bin/sh:

Full dmesg + remain: http://plukky.net/~pluknet/misc/ibmx5.verbosedmesg.txt

This is confirmed by the fact that it started to pass multiuser (up to login)
after I've reduced hw.physmem down to 8GB.

Any tips are appreciated.

-- 
wbr,
pluknet