From: Shaohua Li In the cpu hotplug case, per-cpu data possibly isn't initialized even the system state is 'running'. As the comments say in the original code, some console drivers assume per-cpu resources have been allocated. radeon fb is one such driver, which uses kmalloc. After a CPU is down, the per-cpu data of slab is freed, so the system crashed when printing some info. Signed-off-by: Andrew Morton --- kernel/printk.c | 3 +-- 1 files changed, 1 insertion(+), 2 deletions(-) diff -puN kernel/printk.c~cpu-hotplug-printk-fix kernel/printk.c --- 25/kernel/printk.c~cpu-hotplug-printk-fix 2005-05-26 22:43:09.000000000 -0700 +++ 25-akpm/kernel/printk.c 2005-05-26 22:43:09.000000000 -0700 @@ -588,8 +588,7 @@ asmlinkage int vprintk(const char *fmt, log_level_unknown = 1; } - if (!cpu_online(smp_processor_id()) && - system_state != SYSTEM_RUNNING) { + if (!cpu_online(smp_processor_id())) { /* * Some console drivers may assume that per-cpu resources have * been allocated. So don't allow them to be called by this _