• Tejun Heo's avatar
    percpu: don't assume existence of cpu0 · 04a13c7c
    Tejun Heo authored
    percpu incorrectly assumed that cpu0 was always there which led to the
    following warning and eventual oops on sparc machines w/o cpu0.
    
      WARNING: at mm/percpu.c:651 pcpu_map+0xdc/0x100()
      Modules linked in:
      Call Trace:
        [000000000045eb70] warn_slowpath_common+0x50/0xa0
        [000000000045ebdc] warn_slowpath_null+0x1c/0x40
        [00000000004d493c] pcpu_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: default avatarTejun Heo <tj@kernel.org>
    Reported-by: default avatarMeelis Roos <mroos@linux.ee>
    Cc: David Miller <davem@davemloft.net>
    04a13c7c
percpu.c 36.9 KB