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

Daisuke Nishimura
2009-02-03T03:49:26Z

On Mon, 2 Feb 2009 14:45:06 +0100, Johannes Weiner <hannes@cmpxchg.org> wrote:
> On Mon, Feb 02, 2009 at 06:22:40PM +0530, Balbir Singh wrote:
> > Hi, All,
> >
> > I found the following patch useful while debugging the memory
> > controller. It adds additional information if memcg invoked the OOM.
> >
> > Comments, Suggestions?
> >
> > From: Balbir Singh <balbir@linux.vnet.ibm.com>
> >
> > Description: Add RSS and swap to OOM output from memcg
> >
> > This patch displays memcg values like failcnt, usage and limit
> > when an OOM occurs due to memcg.
> >
> > Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
> > ---
> >
> > include/linux/memcontrol.h | 5 +++++
> > mm/memcontrol.c | 15 +++++++++++++++
> > mm/oom_kill.c | 1 +
> > 3 files changed, 21 insertions(+), 0 deletions(-)
> >
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index 326f45c..2ce1737 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -104,6 +104,7 @@ 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_mem_info(struct mem_cgroup *memcg);
> >
> > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
> > extern int do_swap_account;
> > @@ -270,6 +271,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
> > return NULL;
> > }
> >
> > +void mem_cgroup_print_mem_info(struct mem_cgroup *memcg)
> > +{
> > +}
> > +
> > #endif /* CONFIG_CGROUP_MEM_CONT */
> >
> > #endif /* _LINUX_MEMCONTROL_H */
> > diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> > index 8e4be9c..75eae85 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -813,6 +813,21 @@ bool mem_cgroup_oom_called(struct task_struct *task)
> > rcu_read_unlock();
> > return ret;
> > }
> > +
> > +void mem_cgroup_print_mem_info(struct mem_cgroup *memcg)
> > +{
> > + printk(KERN_WARNING "Memory cgroups's name %s\n",
> > + memcg->css.cgroup->dentry->d_name.name);
> > + printk(KERN_WARNING "Memory cgroup RSS : usage %llu, limit %llu"
> > + " failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE),
> > + res_counter_read_u64(&memcg->res, RES_LIMIT),
> > + res_counter_read_u64(&memcg->res, RES_FAILCNT));
> > + printk(KERN_WARNING "Memory cgroup swap: usage %llu, limit %llu "
> > + "failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE),
> > + res_counter_read_u64(&memcg->res, RES_LIMIT),
> > + res_counter_read_u64(&memcg->res, RES_FAILCNT));
> > +}
> > +
> > /*
> > * Unlike exported interface, "oom" parameter is added. if oom==true,
> > * oom-killer can be invoked.
> > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> > index d3b9bac..b8e53ae 100644
> > --- a/mm/oom_kill.c
> > +++ b/mm/oom_kill.c
> > @@ -392,6 +392,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
> > current->comm, gfp_mask, order, current->oomkilladj);
> > task_lock(current);
> > cpuset_print_task_mems_allowed(current);
> > + mem_cgroup_print_mem_info(mem);
>
> mem is only !NULL when we come from mem_cgroup_out_of_memory(). This
> crashes otherwise in mem_cgroup_print_mem_info(), no?
>
I think you're right.

IMHO, "mem_cgroup_print_mem_info(current)" would be better here,
and call mem_cgroup_from_task at mem_cgroup_print_mem_info.

Thanks,
Daisuke Nishimura.