[PATCH] x86: fix cpu-hotplug regression Commit d435d862baca3e25e5eec236762a43251b1e7ffc ("cpu hotplug: mce: fix cpu hotplug error handling") changed the error handling in mce_cpu_callback.
In cases where not all CPUs are brought up during boot (e.g. using maxcpus and additional_cpus parameters) mce_cpu_callback now returns NOTFIY_BAD because for such CPUs cpu_data is not completely filled when the notifier is called. Thus mce_create_device fails right at its beginning: if (!mce_available(&cpu_data[cpu])) return -EIO; As a quick fix I suggest to check boot_cpu_data for MCE. To reproduce this regression: (1) boot with maxcpus=2 addtional_cpus=2 on a 4 CPU x86-64 system (2) # echo 1 >/sys/devices/system/cpu/cpu2/online -bash: echo: write error: Invalid argument dmesg shows: _cpu_up: attempt to bring up CPU 2 failed Signed-off-by: Andreas Herrmann <[EMAIL PROTECTED]> --- arch/x86/kernel/cpu/mcheck/mce_64.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce_64.c b/arch/x86/kernel/cpu/mcheck/mce_64.c index b9f802e..5112a70 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_64.c +++ b/arch/x86/kernel/cpu/mcheck/mce_64.c @@ -808,7 +808,7 @@ static __cpuinit int mce_create_device(unsigned int cpu) int err; int i; - if (!mce_available(&cpu_data(cpu))) + if (!mce_available(&boot_cpu_data)) return -EIO; memset(&per_cpu(device_mce, cpu).kobj, 0, sizeof(struct kobject)); -- 1.5.3.4 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/