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SubjectRe: [PATCH v12 2/2] Add the missing information for the oom report
The subject is not informative. What is the information?
Add oom victim's memmcg to the oom context information

On Thu 05-07-18 21:20:29, ufo19890607@gmail.com wrote:
> From: yuzhoujian <yuzhoujian@didichuxing.com>
>
> The current oom report doesn't display victim's memcg context during the
> global OOM situation. While this information is not strictly needed, it
> can be really helpful for containerized environments to locate which
> container has lost a process. Now that we have a single line for the oom
> context, we can trivially add both the oom memcg (this can be either
> global_oom or a specific memcg which hits its hard limits) and task_memcg
> which is the victim's memcg.

The <insert your usecase> is clearly missing.

An example of the oom context line would be appropriate.

> Signed-off-by: yuzhoujian <yuzhoujian@didichuxing.com>

The patch looks good otherwise. I would suggest switching cpuset and
memcg information ordering but that is not crucial AFAICS. So you can
add
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
> include/linux/memcontrol.h | 14 +++++++++++---
> mm/memcontrol.c | 36 ++++++++++++++++++++++--------------
> mm/oom_kill.c | 10 ++++++----
> 3 files changed, 39 insertions(+), 21 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6c6fb116e925..96a73f989101 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -491,8 +491,10 @@ void mem_cgroup_handle_over_high(void);
>
> unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg);
>
> -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);
> +
> +void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg);
>
> static inline void mem_cgroup_oom_enable(void)
> {
> @@ -903,7 +905,13 @@ static inline unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
> }
>
> static inline void
> -mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> +mem_cgroup_print_oom_context(struct mem_cgroup *memcg,
> + struct task_struct *p)
> +{
> +}
> +
> +static inline void
> +mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
> {
> }
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e6f0d5ef320a..18deea974cfd 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1119,32 +1119,40 @@ static const char *const memcg1_stat_names[] = {
>
> #define K(x) ((x) << (PAGE_SHIFT-10))
> /**
> - * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
> - * @memcg: The memory cgroup that went over limit
> + * mem_cgroup_print_oom_context: Print OOM context information relevant to
> + * memory controller.
> + * @memcg: The origin memory cgroup that went over limit
> * @p: Task that is going to be killed
> *
> * NOTE: @memcg and @p's mem_cgroup can be different when hierarchy is
> * enabled
> */
> -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)
> {
> - struct mem_cgroup *iter;
> - unsigned int i;
> + struct cgroup *origin_cgrp, *kill_cgrp;
>
> rcu_read_lock();
> -
> + if (memcg) {
> + pr_cont(",oom_memcg=");
> + pr_cont_cgroup_path(memcg->css.cgroup);
> + } else
> + pr_cont(",global_oom");
> if (p) {
> - pr_info("Task in ");
> + pr_cont(",task_memcg=");
> 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 ");
> }
> -
> - pr_cont_cgroup_path(memcg->css.cgroup);
> - pr_cont("\n");
> -
> rcu_read_unlock();
> +}
> +
> +/**
> + * mem_cgroup_print_oom_meminfo: Print OOM memory information relevant to
> + * memory controller.
> + * @memcg: The memory cgroup that went over limit
> + */
> +void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
> +{
> + struct mem_cgroup *iter;
> + unsigned int i;
>
> pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
> K((u64)page_counter_read(&memcg->memory)),
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index c38f224b0d9e..9e80f6c2eb2e 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -430,13 +430,15 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
> dump_stack();
>
> /* one line summary of the oom killer context. */
> - pr_info("oom-kill:constraint=%s,nodemask=%*pbl,task=%s,pid=%5d,uid=%5d",
> + pr_info("oom-kill:constraint=%s,nodemask=%*pbl",
> oom_constraint_text[oc->constraint],
> - nodemask_pr_args(oc->nodemask),
> - p->comm, p->pid, from_kuid(&init_user_ns, task_uid(p)));
> + nodemask_pr_args(oc->nodemask));
> + mem_cgroup_print_oom_context(oc->memcg, p);
> cpuset_print_current_mems_allowed();
> + pr_cont(",task=%s,pid=%5d,uid=%5d\n", p->comm, p->pid,
> + from_kuid(&init_user_ns, task_uid(p)));
> if (is_memcg_oom(oc))
> - mem_cgroup_print_oom_info(oc->memcg, p);
> + mem_cgroup_print_oom_meminfo(oc->memcg);
> else {
> show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
> if (is_dump_unreclaim_slabs())
> --
> 2.14.1
>

--
Michal Hocko
SUSE Labs

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