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SubjectRe: [PATCH v4] Print the memcg's name when system-wide OOM happened
On Mon 21-05-18 03:39:46, ufo19890607 wrote:
> From: yuzhoujian <yuzhoujian@didichuxing.com>
>
> The dump_header does not print the memcg's name when the system
> oom happened. So users cannot locate the certain container which
> contains the task that has been killed by the oom killer.
>
> System oom report will print the memcg's name after this patch,
> so users can get the memcg's path from the oom report and check
> the certain container more quickly.
>
> Changes since v3:
> - rename the helper's name to mem_cgroup_print_oom_memcg_name.
> - add the rcu lock held to the helper.
> - remove the print info of memcg's name in mem_cgroup_print_oom_info.
>
> Changes since v2:
> - add the mem_cgroup_print_memcg_name helper to print the memcg's
> name which contains the task that will be killed by the oom-killer.
>
> Changes since v1:
> - replace adding mem_cgroup_print_oom_info with printing the memcg's
> name only.

This has still the part which is misleading in the global oom context.
So no, it seems that a helper will not do much good. Unless we can
squeeze everything into a single like like David proposed
(http://lkml.kernel.org/r/alpine.DEB.2.21.1805211405300.41872@chino.kir.corp.google.com)
we should simply open code the relevant part of in the global oom path.

> Signed-off-by: yuzhoujian <yuzhoujian@didichuxing.com>
> ---
> include/linux/memcontrol.h | 9 +++++++++
> mm/memcontrol.c | 27 +++++++++++++++++++--------
> mm/oom_kill.c | 1 +
> 3 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index d99b71bc2c66..5fc58beae368 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -464,6 +464,9 @@ void mem_cgroup_handle_over_high(void);
>
> unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg);
>
> +void mem_cgroup_print_oom_memcg_name(struct mem_cgroup *memcg,
> + struct task_struct *p);
> +
> void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
> struct task_struct *p);
>
> @@ -858,6 +861,12 @@ static inline unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
> return 0;
> }
>
> +static inline void
> +mem_cgroup_print_oom_memcg_name(struct mem_cgroup *memcg,
> + struct task_struct *p)
> +{
> +}
> +
> static inline void
> mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> {
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 2bd3df3d101a..138a11edfacb 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1118,19 +1118,15 @@ 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.
> + * mem_cgroup_print_oom_memcg_name: Print the memcg's name which contains the
> + * task that will be killed by the oom-killer.
> * @memcg: The 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_memcg_name(struct mem_cgroup *memcg, struct task_struct *p)
> {
> - struct mem_cgroup *iter;
> - unsigned int i;
> -
> rcu_read_lock();
>
> if (p) {
> @@ -1145,7 +1141,22 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
> pr_cont("\n");
>
> rcu_read_unlock();
> +}
> +
> +/**
> + * mem_cgroup_print_oom_info: Print OOM information relevant to memory controller.
> + * @memcg: The 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)
> +{
> + struct mem_cgroup *iter;
> + unsigned int i;
>
> + mem_cgroup_print_oom_memcg_name(memcg, p);
> pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
> K((u64)page_counter_read(&memcg->memory)),
> K((u64)memcg->memory.limit), memcg->memory.failcnt);
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index 8ba6cb88cf58..3e0b725fb877 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -433,6 +433,7 @@ static void dump_header(struct oom_control *oc, struct task_struct *p)
> if (is_memcg_oom(oc))
> mem_cgroup_print_oom_info(oc->memcg, p);
> else {
> + mem_cgroup_print_oom_memcg_name(oc->memcg, p);
> show_mem(SHOW_MEM_FILTER_NODES, oc->nodemask);
> if (is_dump_unreclaim_slabs())
> dump_unreclaimable_slab();
> --
> 2.14.1

--
Michal Hocko
SUSE Labs

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