Hi Thomas,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/locking/core]
[cannot apply to v5.4-rc6 next-20191108]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Thomas-Gleixner/futex-Cure-robust-PI-futex-exit-races/20191109-061422
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git a0855d24fc22d49cdc25664fb224caee16998683
config: x86_64-randconfig-a003-201944 (attached as .config)
compiler: gcc-5 (Ubuntu 5.5.0-12ubuntu1) 5.5.0 20171010
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from <command-line>:0:0:
   include/linux/futex.h: In function 'futex_init_task':
   include/linux/futex.h:59:5: error: dereferencing pointer to incomplete type 'struct task_struct'
     tsk->robust_list = NULL;
        ^
>> include/linux/futex.h:66:2: error: implicit declaration of function 'mutex_init' [-Werror=implicit-function-declaration]
     mutex_init(&tsk->futex_exit_mutex);
     ^
   cc1: some warnings being treated as errors

vim +/mutex_init +66 include/linux/futex.h

    56	
    57	static inline void futex_init_task(struct task_struct *tsk)
    58	{
  > 59		tsk->robust_list = NULL;
    60	#ifdef CONFIG_COMPAT
    61		tsk->compat_robust_list = NULL;
    62	#endif
    63		INIT_LIST_HEAD(&tsk->pi_state_list);
    64		tsk->pi_state_cache = NULL;
    65		tsk->futex_state = FUTEX_STATE_OK;
  > 66		mutex_init(&tsk->futex_exit_mutex);
    67	}
    68	

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0-DAY kernel test infrastructure                 Open Source Technology Center
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