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

Balbir Singh
2009-02-03T05:35:58Z

* Li Zefan <lizf@cn.fujitsu.com> [2009-02-03 13:24:34]:

> David Rientjes wrote:
> > On Tue, 3 Feb 2009, Balbir Singh wrote:
> >
> >>>> 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);
> >>> I think this can be put outside the task lock. The lock is used to call task_cs() safely in
> >>> cpuset_print_task_mems_allowed().
> >>>
> >> Thanks, I'll work on that in the next version.
> >>
> >
> > I was also wondering about this and assumed that it was necessary to
> > prevent the cgroup from disappearing during the oom. If task_lock() isn't
> > held, is the memcg->css.cgroup->dentry->d_name.name dereference always
> > safe without rcu?
> >
>
> The cgroup won't disappear, since mem_cgroup_out_of_memory() is called with memcg's css refcnt
> increased. :)
>

And this as well, yes!

--
Balbir