Hi,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.7-rc5 next-20160629]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Oleg-Nesterov/kthread-to_live_kthread-needs-try_get_task_stack/20160630-020824
config: i386-tinyconfig (attached as .config)
compiler: gcc-6 (Debian 6.1.1-1) 6.1.1 20160430
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   kernel/kthread.c: In function 'to_live_kthread':
>> kernel/kthread.c:67:23: error: implicit declaration of function 'try_get_task_stack' [-Werror=implicit-function-declaration]
     if (likely(vfork) && try_get_task_stack(k))
                          ^~~~~~~~~~~~~~~~~~
   kernel/kthread.c: In function 'kthread_unpark':
>> kernel/kthread.c:430:3: error: implicit declaration of function 'put_task_stack' [-Werror=implicit-function-declaration]
      put_task_stack(k);
      ^~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/try_get_task_stack +67 kernel/kthread.c

    61		return __to_kthread(k->vfork_done);
    62	}
    63	
    64	static struct kthread *to_live_kthread(struct task_struct *k)
    65	{
    66		struct completion *vfork = ACCESS_ONCE(k->vfork_done);
  > 67		if (likely(vfork) && try_get_task_stack(k))
    68			return __to_kthread(vfork);
    69		return NULL;
    70	}

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0-DAY kernel test infrastructure                Open Source Technology Center
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