acpi_restore_state_mem() in arch/i386/kernel/acpi/sleep.c uses 
zap_low_mappings() and isn't SMP-specific.  zap_low_mappings() is 
extern'd in include/asm-i386/smp.h, but wrapped in CONFIG_SMP ifdefs. 
This should be exported for non-CONFIG_SMP as well.  This patch does that.

Cheers!

-Matt