[akpm-mm:mm-unstable 179/192] mm/zswap.c:298:62: warning: pointer/integer type mismatch in conditional expression

[akpm-mm:mm-unstable 179/192] mm/zswap.c:298:62: warning: pointer/integer type mismatch in conditional expression

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   cb1d236cb1038fa1bbae9913803f1c655b86d931
commit: 70dd375afcfe1839321ea8a65749404a99f0e773 [179/192] zswap: make shrinking memcg-aware
config: arc-randconfig-001-20231129 (https://download.01.org/0day-ci/archive/20231130/202311300811.B6BZeDjn-lkp@intel.com/config)
compiler: arceb-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231130/202311300811.B6BZeDjn-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/202311300811.B6BZeDjn-lkp@intel.com/

All warnings (new ones prefixed by >>):

   mm/zswap.c: In function 'mem_cgroup_from_entry':
   mm/zswap.c:298:31: error: implicit declaration of function 'obj_cgroup_memcg'; did you mean 'obj_cgroup_put'? [-Werror=implicit-function-declaration]
     298 |         return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
         |                               ^~~~~~~~~~~~~~~~
         |                               obj_cgroup_put
>> mm/zswap.c:298:62: warning: pointer/integer type mismatch in conditional expression
     298 |         return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
         |                                                              ^
   mm/zswap.c: In function 'shrink_worker':
   mm/zswap.c:825:31: error: invalid use of undefined type 'struct mem_cgroup'
     825 |                 css_get(&memcg->css);
         |                               ^~
   cc1: some warnings being treated as errors


vim +298 mm/zswap.c

   294	
   295	/* should be called under RCU */
   296	static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry)
   297	{
 > 298		return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL;
   299	}
   300	

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