Hi Waiman,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/locking/core]
[also build test ERROR on v4.16-rc7 next-20180326]
[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/Waiman-Long/locking-rwsem-Add-DEBUG_RWSEMS-to-look-for-lock-unlock-mismatches/20180327-151310
config: i386-allmodconfig (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All error/warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:10:0,
                    from kernel/locking/rwsem.c:9:
   kernel/locking/rwsem.c: In function 'up_read_non_owner':
>> kernel/locking/rwsem.c:217:23: error: implicit declaration of function 'RWSEM_WRITER_OWNED'; did you mean 'RWSEM_READER_OWNED'? [-Werror=implicit-function-declaration]
     DEBUG_RWSEMS_WARN_ON(RWSEM_WRITER_OWNED(sem->owner));
                          ^
   include/linux/compiler.h:77:42: note: in definition of macro 'unlikely'
    # define unlikely(x) __builtin_expect(!!(x), 0)
                                             ^
>> kernel/locking/rwsem.h:20:33: note: in expansion of macro 'DEBUG_LOCKS_WARN_ON'
    #define DEBUG_RWSEMS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c)
                                    ^~~~~~~~~~~~~~~~~~~
>> kernel/locking/rwsem.c:217:2: note: in expansion of macro 'DEBUG_RWSEMS_WARN_ON'
     DEBUG_RWSEMS_WARN_ON(RWSEM_WRITER_OWNED(sem->owner));
     ^~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +217 kernel/locking/rwsem.c

   214	
   215	void up_read_non_owner(struct rw_semaphore *sem)
   216	{
 > 217		DEBUG_RWSEMS_WARN_ON(RWSEM_WRITER_OWNED(sem->owner));
   218		__up_read(sem);
   219	}
   220	

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