Re: [-mm patch] Show memcg information during OOM (v3)

[Li Zefan <lizf@cn.fujitsu.com>]

> @@ -104,6 +104,8 @@ struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
>  						      struct zone *zone);
>  struct zone_reclaim_stat*
>  mem_cgroup_get_reclaim_stat_from_page(struct page *page);
> +extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
> +					struct task_struct *p);
>  
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
>  extern int do_swap_account;
> @@ -270,6 +272,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
>  	return NULL;
>  }
>  
> +void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> +{

should be static inline, otherwise it won't compile if CONFIG_CGROUP_MEM_CONT=n

> +}
> +
>  #endif /* CONFIG_CGROUP_MEM_CONT */
>  

> +void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> +{
> +	struct cgroup *task_cgrp;
> +	struct cgroup *mem_cgrp;
> +	/*
> +	 * Need a buffer on stack, can't rely on allocations. The code relies

I think it's in .bss section, but not on stack, and it's better to explain why
the static buffer is safe in the comment.

> +	 * on the assumption that OOM is serialized for memory controller.
> +	 * If this assumption is broken, revisit this code.
> +	 */
> +	static char task_memcg_name[PATH_MAX];
> +	static char memcg_name[PATH_MAX];
> +	int ret;