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 virt_to_phys() to non-existent addresses. Signed-off-by: Dave Hansen --- memhotplug1-dave/arch/i386/mm/ioremap.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-) diff -puN arch/i386/mm/ioremap.c~A2-ioremap-valid-pfns arch/i386/mm/ioremap.c --- memhotplug1/arch/i386/mm/ioremap.c~A2-ioremap-valid-pfns 2004-11-04 16:45:29.000000000 -0800 +++ memhotplug1-dave/arch/i386/mm/ioremap.c 2004-11-04 16:45:29.000000000 -0800 @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -130,7 +131,7 @@ void __iomem * __ioremap(unsigned long p /* * Don't allow anybody to remap normal RAM that we're using.. */ - if (phys_addr < virt_to_phys(high_memory)) { + if (phys_addr <= virt_to_phys(high_memory-1)) { char *t_addr, *t_end; struct page *page; @@ -197,7 +198,7 @@ void __iomem *ioremap_nocache (unsigned /* Guaranteed to be > phys_addr, as per __ioremap() */ last_addr = phys_addr + size - 1; - if (last_addr < virt_to_phys(high_memory)) { + if (last_addr <= virt_to_phys(high_memory-1)) { struct page *ppage = virt_to_page(__va(phys_addr)); unsigned long npages; @@ -232,7 +233,7 @@ void iounmap(volatile void __iomem *addr return; } - if ((p->flags >> 24) && p->phys_addr < virt_to_phys(high_memory)) { + if ((p->flags >> 24) && p->phys_addr <= virt_to_phys(high_memory-1)) { change_page_attr(virt_to_page(__va(p->phys_addr)), p->size >> PAGE_SHIFT, PAGE_KERNEL); _