tree:   git://git.cmpxchg.org/linux-mmotm.git master
head:   3fe55fa60ae65a3c8348ae1bfc6fd2e5c3f10654
commit: f44aea42422dcbc58cd8cc4fc8c564b91a283cef [207/422] memcg: rework memcg_update_kmem_limit synchronization
config: x86_64-randconfig-c2-0110 (attached as .config)

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings:

   mm/memcontrol.c: In function 'mem_cgroup_css_online':
>> mm/memcontrol.c:5884:5: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
     if (ret)
        ^
   mm/memcontrol.c:5192:6: note: 'ret' was declared here
     int ret;
         ^

vim +/ret +5884 mm/memcontrol.c

3c11ecf4 KAMEZAWA Hiroyuki 2010-05-26  5868  		return -EINVAL;
3c11ecf4 KAMEZAWA Hiroyuki 2010-05-26  5869  	}
c0ff4b85 Raghavendra K T   2011-11-02  5870  	memcg->oom_kill_disable = val;
4d845ebf KAMEZAWA Hiroyuki 2010-06-29  5871  	if (!val)
c0ff4b85 Raghavendra K T   2011-11-02  5872  		memcg_oom_recover(memcg);
0999821b Glauber Costa     2013-02-22  5873  	mutex_unlock(&memcg_create_mutex);
3c11ecf4 KAMEZAWA Hiroyuki 2010-05-26  5874  	return 0;
3c11ecf4 KAMEZAWA Hiroyuki 2010-05-26  5875  }
3c11ecf4 KAMEZAWA Hiroyuki 2010-05-26  5876  
c255a458 Andrew Morton     2012-07-31  5877  #ifdef CONFIG_MEMCG_KMEM
cbe128e3 Glauber Costa     2012-04-09  5878  static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
e5671dfa Glauber Costa     2011-12-11  5879  {
55007d84 Glauber Costa     2012-12-18  5880  	int ret;
55007d84 Glauber Costa     2012-12-18  5881  
2633d7a0 Glauber Costa     2012-12-18  5882  	memcg->kmemcg_id = -1;
55007d84 Glauber Costa     2012-12-18  5883  	ret = memcg_propagate_kmem(memcg);
55007d84 Glauber Costa     2012-12-18 @5884  	if (ret)
55007d84 Glauber Costa     2012-12-18  5885  		return ret;
2633d7a0 Glauber Costa     2012-12-18  5886  
1d62e436 Glauber Costa     2012-04-09  5887  	return mem_cgroup_sockets_init(memcg, ss);
573b400d Michel Lespinasse 2013-04-29  5888  }
e5671dfa Glauber Costa     2011-12-11  5889  
10d5ebf4 Li Zefan          2013-07-08  5890  static void memcg_destroy_kmem(struct mem_cgroup *memcg)
d1a4c0b3 Glauber Costa     2011-12-11  5891  {
1d62e436 Glauber Costa     2012-04-09  5892  	mem_cgroup_sockets_destroy(memcg);

:::::: The code at line 5884 was first introduced by commit
:::::: 55007d849759252ddd573aeb36143b947202d509 memcg: allocate memory for memcg caches whenever a new memcg appears

:::::: TO: Glauber Costa <glommer@parallels.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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