Re: [-mm patch] Show memcg information during OOM (v2)

Balbir Singh
2009-02-03T09:00:47Z

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-02-03 17:04:27]:

> On Tue, 3 Feb 2009 12:57:01 +0530
> Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
>
> > Checkpatch caught an additional space, so here is the patch again
> >
> >
> > Description: Add RSS and swap to OOM output from memcg
> >
> > From: Balbir Singh <balbir@linux.vnet.ibm.com>
> >
> > Changelog v2..v1:
> >
> > 1. Add more information about task's memcg and the memcg
> > over it's limit
> > 2. Print data in KB
> > 3. Move the print routine outside task_lock()
> > 4. Use rcu_read_lock() around cgroup_path, strictly speaking it
> > is not required, but relying on the current memcg implementation
> > is not a good idea.
> >
> >
> > This patch displays memcg values like failcnt, usage and limit
> > when an OOM occurs due to memcg.
> >
> > Thanks go out to Johannes Weiner, Li Zefan, David Rientjes,
> > Kamezawa Hiroyuki, Daisuke Nishimura and KOSAKI Motohiro for
> > review.
> >
>
> IIUC, this oom_kill is serialized by memcg_tasklist mutex.
> Then, you don't have to allocate buffer on stack.
>
>
> > +void mem_cgroup_print_mem_info(struct mem_cgroup *memcg, struct task_struct *p)
> > +{
> > + struct cgroup *task_cgrp;
> > + struct cgroup *mem_cgrp;
> > + /*
> > + * Need a buffer on stack, can't rely on allocations.
> > + */
> > + char task_memcg_name[MEM_CGROUP_OOM_BUF_SIZE];
> > + char memcg_name[MEM_CGROUP_OOM_BUF_SIZE];
> > + int ret;
> > +
>
> making this as
>
> static char task_memcg_name[PATH_MAX];
> static char memcg_name[PATH_MAX];
>
> is ok, I think. and the patch will be more simple.
>

I've mentioned it in the NOTE section as well, I wanted more opinions
before going that route. I'll resend v3.