Re: [linux-next:master 12342/12641] mm/vmscan.c:205:7: error: implicit declaration of function 'memcg_expand_shrinker_maps'; did you mean 'memcg_set_shrinker_bit'?

[Randy Dunlap <rdunlap@infradead.org>]

On 7/5/19 3:16 PM, Randy Dunlap wrote:
> On 7/5/19 2:20 PM, Andrew Morton wrote:
>> On Fri, 5 Jul 2019 21:09:24 +0800 kbuild test robot <lkp@intel.com> wrote:
>>
>>> tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git master
>>> head:   22c45ec32b4a9fa8c48ef4f5bf9b189b307aae12
>>> commit: 8236f517d69e2217f5200d7f700e8b18b01c94c8 [12342/12641] mm: shrinker: make shrinker not depend on memcg kmem
>>> config: x86_64-randconfig-s2-07051907 (attached as .config)
>>> compiler: gcc-7 (Debian 7.4.0-9) 7.4.0
>>> reproduce:
>>>         git checkout 8236f517d69e2217f5200d7f700e8b18b01c94c8
>>>         # 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 error/warnings (new ones prefixed by >>):
>>>
>>>    mm/vmscan.c: In function 'prealloc_memcg_shrinker':
>>>>> mm/vmscan.c:205:7: error: implicit declaration of function 'memcg_expand_shrinker_maps'; did you mean 'memcg_set_shrinker_bit'? [-Werror=implicit-function-declaration]
>>>       if (memcg_expand_shrinker_maps(id)) {
>>>           ^~~~~~~~~~~~~~~~~~~~~~~~~~
>>>           memcg_set_shrinker_bit
>>>    In file included from include/linux/rbtree.h:22:0,
>>>                     from include/linux/mm_types.h:10,
>>>                     from include/linux/mmzone.h:21,
>>>                     from include/linux/gfp.h:6,
>>>                     from include/linux/mm.h:10,
>>>                     from mm/vmscan.c:17:
>>>    mm/vmscan.c: In function 'shrink_slab_memcg':
>>>>> mm/vmscan.c:593:54: error: 'struct mem_cgroup_per_node' has no member named 'shrinker_map'
>>
>> This?
>>
>> --- a/include/linux/memcontrol.h~mm-shrinker-make-shrinker-not-depend-on-memcg-kmem-fix
>> +++ a/include/linux/memcontrol.h
>> @@ -128,7 +128,7 @@ struct mem_cgroup_per_node {
>>  
>>  	struct mem_cgroup_reclaim_iter	iter[DEF_PRIORITY + 1];
>>  
>> -#ifdef CONFIG_MEMCG_KMEM
>> +#ifdef CONFIG_MEMCG
>>  	struct memcg_shrinker_map __rcu	*shrinker_map;
>>  #endif
>>  	struct rb_node		tree_node;	/* RB tree node */
>> @@ -1272,6 +1272,7 @@ static inline bool mem_cgroup_under_sock
>>  
>>  struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep);
>>  void memcg_kmem_put_cache(struct kmem_cache *cachep);
>> +extern int memcg_expand_shrinker_maps(int new_id);
>>  
>>  #ifdef CONFIG_MEMCG_KMEM
>>  int __memcg_kmem_charge(struct page *page, gfp_t gfp, int order);
>> @@ -1339,8 +1340,6 @@ static inline int memcg_cache_id(struct
>>  	return memcg ? memcg->kmemcg_id : -1;
>>  }
>>  
>> -extern int memcg_expand_shrinker_maps(int new_id);
>> -
>>  extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
>>  				   int nid, int shrinker_id);
>>  #else
>> _
>>
> 
> Now I see this:
> 
> ld: mm/vmscan.o: in function `prealloc_shrinker':
> vmscan.c:(.text+0x3090): undefined reference to `memcg_expand_shrinker_maps'
> 
> 
> And for the record, I reported this yesterday on mmotm:
> https://lore.kernel.org/lkml/9cbdb785-b51d-9419-6b9a-ec282a4e4fa2@infradead.org/
> 
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> 
> 
> thanks,

I did a similar change as Andrew's, but to mm/memcontrol.c, but that just
causes duplicate function definition errors from <linux/memcontrol.h> because
it has stubs for some functions that are now being built.


-- 
~Randy