When CONFIG_HIGHMEM=y, but ZONE_NORMAL isn't quite full, there is, of course, no actual memory at *high_memory. This isn't a problem with normal virt<->phys translations because it's never dereferenced, but CONFIG_NONLINEAR is a bit more finicky. So, don't do __va() in non-existent addresses. The arithmetic with void* and char* is the same, but I find it a little more obvious what's goin on when char* is used explicitly. Signed-off-by: Dave Hansen --- memhotplug-dave/arch/i386/mm/init.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff -puN arch/i386/mm/init.c~A3-highmem_start-valid_addrs arch/i386/mm/init.c --- memhotplug/arch/i386/mm/init.c~A3-highmem_start-valid_addrs 2004-12-10 13:52:26.000000000 -0800 +++ memhotplug-dave/arch/i386/mm/init.c 2004-12-10 13:52:26.000000000 -0800 @@ -582,9 +582,9 @@ void __init mem_init(void) set_max_mapnr_init(); #ifdef CONFIG_HIGHMEM - high_memory = (void *) __va(highstart_pfn * PAGE_SIZE); + high_memory = (char *) __va(highstart_pfn * PAGE_SIZE - 1) + 1; #else - high_memory = (void *) __va(max_low_pfn * PAGE_SIZE); + high_memory = (char *) __va(max_low_pfn * PAGE_SIZE - 1) + 1; #endif /* this will put all low memory onto the freelists */ _