map+0xdc/0x100
    [00000000004d59a4] pcpu_alloc+0x3e4/0x4e0
    [00000000004d5af8] __alloc_percpu+0x18/0x40
    [00000000005b112c] __percpu_counter_init+0x4c/0xc0
  ...
  Unable to handle kernel NULL pointer dereference
  ...
   I7: <sysfs_new_dirent+0x30/0x120>
   Disabling lock debugging due to kernel taint
   Caller[000000000053c1b0]: sysfs_new_dirent+0x30/0x120
   Caller[000000000053c7a4]: create_dir+0x24/0xc0
   Caller[000000000053c870]: sysfs_create_dir+0x30/0x80
   Caller[00000000005990e8]: kobject_add_internal+0xc8/0x200
  ...
   Kernel panic - not syncing: Attempted to kill the idle task!

This patch fixes the problem by backporting parts from devel branch to
make percpu core not depend on the existence of cpu0.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Meelis Roos <mroos@linux.ee>
Cc: David Miller <davem@davemloft.net>
خلا