Messages in this thread | | | Date | Tue, 3 Feb 2009 17:04:27 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [-mm patch] Show memcg information during OOM (v2) |
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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.
Thanks, -kame
> + if (!memcg) > + return; > + > + mem_cgrp = memcg->css.cgroup; > + task_cgrp = mem_cgroup_from_task(p)->css.cgroup; > + > + rcu_read_lock(); > + ret = cgroup_path(task_cgrp, task_memcg_name, MEM_CGROUP_OOM_BUF_SIZE); > + if (ret < 0) { > + /* > + * Unfortunately, we are unable to convert to a useful name > + * But we'll still print out the usage information > + */ > + rcu_read_unlock(); > + goto done; > + } > + ret = cgroup_path(mem_cgrp, memcg_name, MEM_CGROUP_OOM_BUF_SIZE); > + if (ret < 0) { > + rcu_read_unlock(); > + goto done; > + } > + > + rcu_read_unlock(); > + > + printk(KERN_INFO "Task in %s killed as a result of limit of %s\n", > + task_memcg_name, memcg_name); > +done: > + > + printk(KERN_INFO "memory: usage %llukB, limit %llukB, failcnt %llu\n", > + res_counter_read_u64(&memcg->res, RES_USAGE) >> 10, > + res_counter_read_u64(&memcg->res, RES_LIMIT) >> 10, > + res_counter_read_u64(&memcg->res, RES_FAILCNT)); > + printk(KERN_INFO "memory+swap: usage %llukB, limit %llukB, " > + "failcnt %llu\n", > + res_counter_read_u64(&memcg->memsw, RES_USAGE) >> 10, > + res_counter_read_u64(&memcg->memsw, RES_LIMIT) >> 10, > + res_counter_read_u64(&memcg->memsw, 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..951356f 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -394,6 +394,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, > cpuset_print_task_mems_allowed(current); > task_unlock(current); > dump_stack(); > + mem_cgroup_print_mem_info(mem, current); > show_mem(); > if (sysctl_oom_dump_tasks) > dump_tasks(mem); > > -- > Balbir >
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