Re: [linux-next:master 4839/5501] mm/shmem.c:139:24: warning: 'huge_shmem_orders_lock' defined but not used

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 2024/6/15 22:15, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   6906a84c482f098d31486df8dc98cead21cce2d0
> commit: dfe69b2f4ed49aee4a46f09010f7888ee289083d [4839/5501] mm: shmem: add multi-size THP sysfs interface for anonymous shmem
> config: mips-randconfig-r034-20220430 (https://download.01.org/0day-ci/archive/20240615/202406152213.CoQNZR6z-lkp@intel.com/config)
> compiler: mips-linux-gcc (GCC) 13.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240615/202406152213.CoQNZR6z-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202406152213.CoQNZR6z-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
>     In file included from include/linux/spinlock.h:89,
>                      from include/linux/wait.h:9,
>                      from include/linux/wait_bit.h:8,
>                      from include/linux/fs.h:6,
>                      from mm/shmem.c:24:
>>> mm/shmem.c:139:24: warning: 'huge_shmem_orders_lock' defined but not used [-Wunused-variable]
>       139 | static DEFINE_SPINLOCK(huge_shmem_orders_lock);
>           |                        ^~~~~~~~~~~~~~~~~~~~~~
>     include/linux/spinlock_types.h:43:44: note: in definition of macro 'DEFINE_SPINLOCK'
>        43 | #define DEFINE_SPINLOCK(x)      spinlock_t x = __SPIN_LOCK_UNLOCKED(x)
>           |                                            ^
>     mm/shmem.c:138:22: warning: 'huge_shmem_orders_within_size' defined but not used [-Wunused-variable]
>       138 | static unsigned long huge_shmem_orders_within_size __read_mostly;
>           |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>     mm/shmem.c:136:22: warning: 'huge_shmem_orders_madvise' defined but not used [-Wunused-variable]
>       136 | static unsigned long huge_shmem_orders_madvise __read_mostly;
>           |                      ^~~~~~~~~~~~~~~~~~~~~~~~~
>     mm/shmem.c:135:22: warning: 'huge_shmem_orders_always' defined but not used [-Wunused-variable]
>       135 | static unsigned long huge_shmem_orders_always __read_mostly;
>           |                      ^~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> vim +/huge_shmem_orders_lock +139 mm/shmem.c
> 
>     133	
>     134	#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>     135	static unsigned long huge_shmem_orders_always __read_mostly;
>     136	static unsigned long huge_shmem_orders_madvise __read_mostly;
>     137	static unsigned long huge_shmem_orders_inherit __read_mostly;
>     138	static unsigned long huge_shmem_orders_within_size __read_mostly;
>   > 139	static DEFINE_SPINLOCK(huge_shmem_orders_lock);
>     140	#endif
>     141	

Thanks for reporting. I should move the 'huge_shmem_orders_lock' under 
CONFIG_SYSFS config.

@Andrew, please help to squash the following fix into this patch. Thanks.

diff --git a/mm/shmem.c b/mm/shmem.c
index 4acaf02bfe44..d09c6bf1f28a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -136,7 +136,6 @@ static unsigned long huge_shmem_orders_always 
__read_mostly;
  static unsigned long huge_shmem_orders_madvise __read_mostly;
  static unsigned long huge_shmem_orders_inherit __read_mostly;
  static unsigned long huge_shmem_orders_within_size __read_mostly;
-static DEFINE_SPINLOCK(huge_shmem_orders_lock);
  #endif

  #ifdef CONFIG_TMPFS
@@ -4918,6 +4917,7 @@ static ssize_t shmem_enabled_store(struct kobject 
*kobj,
  }

  struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
+static DEFINE_SPINLOCK(huge_shmem_orders_lock);

  static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj,
                                           struct kobj_attribute *attr, 
char *buf)