Hi Wanpeng, Kernel build failed on tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm head: 37e2ad4953983527f7bdb6831bf478eedcc84082 commit: 442d53f161093de78f0aafcd3ec2a6345de42890 [164/309] memcg: add mem_cgroup_from_css() helper config: i386-randconfig-k007 (attached as .config) Build errors: mm/memcontrol.c:871:2: error: implicit declaration of function 'mem_cgroup_from_css' [-Werror=implicit-function-declaration] vim +871 mm/memcontrol.c 868 869 struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont) 870 { > 871 return mem_cgroup_from_css( 872 cgroup_subsys_state(cont, mem_cgroup_subsys_id)); 873 } 874 mem_cgroup_from_css() is defined inside CONFIG_MEMCG_KMEM and used outside of it. --- 0-DAY kernel build testing backend Open Source Technology Centre Fengguang Wu Intel Corporation