Subject: [PATCH] initrd: Fix virtual/physical mix-up in overwrite test From: Geert Uytterhoeven On recent kernels, I get the following error when using an initrd: | initrd overwritten (0x00b78000 < 0x07668000) - disabling it. My Amiga 4000 has 12 MiB of RAM at physical address 0x07400000 (virtual 0x00000000). The initrd is located at the end of RAM: 0x00b78000 - 0x00c00000 (virtual). The overwrite test compares the (virtual) initrd location to the (physical) first available memory location, which fails. This patch converts initrd_start to a page frame number, so it can safely be compared with min_low_pfn. Before the introduction of discontiguous memory support on m68k (12d810c1b8c2b913d48e629e2b5c01d105029839), min_low_pfn was just left untouched by the m68k-specific code (zero, I guess), and everything worked fine. Signed-off-by: Geert Uytterhoeven --- On several platforms, initrd_below_start_ok is set to 1: | arch/mips/kernel/setup.c: initrd_below_start_ok = 1; | arch/parisc/mm/init.c: initrd_below_start_ok = 1; | arch/powerpc/kernel/prom.c: initrd_below_start_ok = 1; | arch/ppc/platforms/hdpu.c: initrd_below_start_ok = 1; | arch/xtensa/kernel/setup.c: initrd_below_start_ok = 1; Some of these may be workarounds for this bug. Please check. init/main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/init/main.c +++ b/init/main.c @@ -629,9 +629,10 @@ asmlinkage void __init start_kernel(void #ifdef CONFIG_BLK_DEV_INITRD if (initrd_start && !initrd_below_start_ok && - initrd_start < min_low_pfn << PAGE_SHIFT) { + page_to_pfn(virt_to_page(initrd_start)) < min_low_pfn) { printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - " - "disabling it.\n",initrd_start,min_low_pfn << PAGE_SHIFT); + "disabling it.\n", + page_to_pfn(virt_to_page(initrd_start)), min_low_pfn); initrd_start = 0; } #endif