Re: [PATCH v7 2/2] Refactor part of the oom report in dump_header

From: Tetsuo Handa
Date: Sun Jun 03 2018 - 10:45:32 EST


On 2018/06/02 20:58, yuzhoujian wrote:
> -void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> +void mem_cgroup_print_oom_context(struct mem_cgroup *memcg, struct task_struct *p,
> + enum oom_constraint constraint, nodemask_t *nodemask)
> {
> - struct mem_cgroup *iter;
> - unsigned int i;
> + static char origin_memcg_name[NAME_MAX], kill_memcg_name[NAME_MAX];
> + struct cgroup *origin_cgrp, *kill_cgrp;
>
> rcu_read_lock();
> -
> - if (p) {
> - pr_info("Task in ");
> - pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
> - pr_cont(" killed as a result of limit of ");
> - } else {
> - pr_info("Memory limit reached of cgroup ");
> + if (memcg) {
> + origin_cgrp = memcg->css.cgroup;
> + cgroup_path(origin_cgrp, origin_memcg_name, NAME_MAX);
> }
> -
> - pr_cont_cgroup_path(memcg->css.cgroup);
> - pr_cont("\n");
> -
> + kill_cgrp = task_cgroup(p, memory_cgrp_id);
> + cgroup_path(kill_cgrp, kill_memcg_name, NAME_MAX);
> +
> + if (p)
> + pr_info("oom-kill:constraint=%s,nodemask=%*pbl,origin_memcg=%s,kill_memcg=%s,task=%s,pid=%5d,uid=%5d\n",
> + oom_constraint_text[constraint], nodemask_pr_args(nodemask),
> + strlen(origin_memcg_name) ? origin_memcg_name : "(null)",

Since origin_memcg_name is printed for both memcg OOM and !memcg OOM,
it is strange that origin_memcg_name is updated only when memcg != NULL.
Have you really tested !memcg OOM case?