From 54ffaa45c5f572ff6c344ca583137d0edf2d78cc Mon Sep 17 00:00:00 2001 From: Ingo Molnar <mingo@elte.hu> Date: Fri, 19 Oct 2007 20:35:02 +0200 Subject: [PATCH] x86: fix CONFIG_NUMA and nosmp | maxcpus=0/1 crash x86 NUMA kernels crash in the scheduler setup code if "nosmp" or "maxcpus=0" is passed on the boot command line: | Brought up 1 CPUs | BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000 | printing eip: c011f0b5 *pde = 00000000 | Oops: 0000 [#1] SMP | | Pid: 1, comm: swapper Not tainted (2.6.23 #67) | EIP: 0060:[<c011f0b5>] EFLAGS: 00010246 CPU: 0 | EIP is at sd_degenerate+0x35/0x40 the reason is sloppy spaghetti code in smpboot_32.c that resulted in a missing map_cpu_to_logical_apicid() call - which also had the side-effect of setting up the cpu_2_node[] entry for the lone CPU. That resulted in node_to_cpumask(0) resulting in 00000000 - confusing the sched-domains setup code. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/smpboot_32.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kernel/smpboot_32.c b/arch/x86/kernel/smpboot_32.c index be3faac0471..65e5de7d64d 100644 --- a/arch/x86/kernel/smpboot_32.c +++ b/arch/x86/kernel/smpboot_32.c @@ -1008,6 +1008,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus) printk(KERN_ERR "... forcing use of dummy APIC emulation. (tell your hw vendor)\n"); smpboot_clear_io_apic_irqs(); phys_cpu_present_map = physid_mask_of_physid(0); + map_cpu_to_logical_apicid(); cpu_set(0, per_cpu(cpu_sibling_map, 0)); cpu_set(0, per_cpu(cpu_core_map, 0)); return; @@ -1029,6 +1030,7 @@ static void __init smp_boot_cpus(unsigned int max_cpus) } smpboot_clear_io_apic_irqs(); phys_cpu_present_map = physid_mask_of_physid(0); + map_cpu_to_logical_apicid(); cpu_set(0, per_cpu(cpu_sibling_map, 0)); cpu_set(0, per_cpu(cpu_core_map, 0)); return; -- 2.41.3