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Date: Fri, 09 Nov 2012 18:23:07 +0800
From: Sha Zhengju <handai.szj@...il.com>
To: Michal Hocko <mhocko@...e.cz>
CC: Sha Zhengju <handai.szj@...il.com>, linux-mm@...ck.org,
cgroups@...r.kernel.org, kamezawa.hiroyu@...fujitsu.com,
akpm@...ux-foundation.org, rientjes@...gle.com,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] memcg, oom: provide more precise dump info while memcg
oom happening
On 11/09/2012 12:25 AM, Michal Hocko wrote:
> On Thu 08-11-12 23:52:47, Sha Zhengju wrote:
> [...]
>> (2) After change
>> [ 269.225628] mal invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
>> [ 269.225633] mal cpuset=/ mems_allowed=0-1
>> [ 269.225636] Pid: 4616, comm: mal Not tainted 3.6.0+ #25
>> [ 269.225637] Call Trace:
>> [ 269.225647] [<ffffffff8111b9c4>] dump_header+0x84/0xd0
>> [ 269.225650] [<ffffffff8111c691>] oom_kill_process+0x331/0x350
>> [ 269.225710] .......(call trace)
>> [ 269.225713] [<ffffffff81517325>] page_fault+0x25/0x30
>> [ 269.225716] Task in /1/2 killed as a result of limit of /1
>> [ 269.225718] memory: usage 511732kB, limit 512000kB, failcnt 5071
>> [ 269.225720] memory+swap: usage 563200kB, limit 563200kB, failcnt 57
>> [ 269.225721] kmem: usage 0kB, limit 9007199254740991kB, failcnt 0
>> [ 269.225722] Memory cgroup stats:cache:8KB rss:511724KB mapped_file:4KB swap:51468KB inactive_anon:265864KB active_anon:245832KB inactive_file:0KB active_file:0KB unevictable:0KB
>> [ 269.225741] [ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name
>> [ 269.225757] [ 4554] 0 4554 16626 473 17 25 0 bash
>> [ 269.225759] [ 4611] 0 4611 103328 90231 208 12260 0 mal
>> [ 269.225762] [ 4616] 0 4616 103328 32799 88 7562 0 mal
>> [ 269.225764] Memory cgroup out of memory: Kill process 4611 (mal) score 699 or sacrifice child
>> [ 269.225766] Killed process 4611 (mal) total-vm:413312kB, anon-rss:360632kB, file-rss:292kB
>>
>> This version provides more pointed info for memcg in "Memory cgroup stats" section.
> Looks much better!
>
>> Change log:
>> v3<--- v2
>> 1. fix towards hierarchy
>> 2. undo rework dump_tasks
>> v2<--- v1
>> 1. some modification towards hierarchy
>> 2. rework dump_tasks
>> 3. rebased on Michal's mm tree since-3.6
>>
>> Signed-off-by: Sha Zhengju<handai.szj@...bao.com>
>> ---
>> mm/memcontrol.c | 41 +++++++++++++++++++++++++++++++----------
>> mm/oom_kill.c | 6 ++++--
>> 2 files changed, 35 insertions(+), 12 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 0eab7d5..17317fa 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
> [...]
>> @@ -1501,8 +1509,8 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
>> spin_unlock_irqrestore(&memcg->move_lock, *flags);
>> }
>>
>> +#define K(x) ((x)<< (PAGE_SHIFT-10))
>> /**
>> - * mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
> No need to remove this just fix it:
> * 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
>> *
>> @@ -1520,8 +1528,10 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
>> */
>> static char memcg_name[PATH_MAX];
>> int ret;
>> + struct mem_cgroup *mi;
>> + unsigned int i;
>>
>> - if (!memcg || !p)
>> + if (!p)
>> return;
>>
>> rcu_read_lock();
>> @@ -1569,6 +1579,25 @@ done:
>> res_counter_read_u64(&memcg->kmem, RES_USAGE)>> 10,
>> res_counter_read_u64(&memcg->kmem, RES_LIMIT)>> 10,
>> res_counter_read_u64(&memcg->kmem, RES_FAILCNT));
>> +
>> + printk(KERN_INFO "Memory cgroup stats:");
> "Memory cgroup hierarchy stats" is probably a better fit with the
> current implementation.
>
>> + for (i = 0; i< MEM_CGROUP_STAT_NSTATS; i++) {
>> + long long val = 0;
>> + if (i == MEM_CGROUP_STAT_SWAP&& !do_swap_account)
>> + continue;
>> + for_each_mem_cgroup_tree(mi, memcg)
>> + val += mem_cgroup_read_stat(mi, i);
>> + printk(KERN_CONT "%s:%lldKB ", mem_cgroup_stat_names[i], K(val));
>> + }
>> +
>> + for (i = 0; i< NR_LRU_LISTS; i++) {
>> + unsigned long long val = 0;
>> +
>> + for_each_mem_cgroup_tree(mi, memcg)
>> + val += mem_cgroup_nr_lru_pages(mi, BIT(i));
>> + printk(KERN_CONT "%s:%lluKB ", mem_cgroup_lru_names[i], K(val));
>> + }
>> + printk(KERN_CONT "\n");
> This is nice and simple I am just thinking whether it is enough. Say
> that you have a deeper hierarchy and the there is a safety limit in the
> its root
> A (limit)
> /|\
> B C D
> |\
> E F
>
> and we trigger an OOM on the A's limit. Now we know that something blew
> up but what it was we do not know. Wouldn't it be better to swap the for
> and for_each_mem_cgroup_tree loops? Then we would see the whole
> hierarchy and can potentially point at the group which doesn't behave.
> Memory cgroup stats for A/: ...
> Memory cgroup stats for A/B/: ...
> Memory cgroup stats for A/C/: ...
> Memory cgroup stats for A/D/: ...
> Memory cgroup stats for A/D/E/: ...
> Memory cgroup stats for A/D/F/: ...
>
> Would it still fit in with your use case?
> [...]
We haven't used those complicate hierarchy yet, but it sounds a good
suggestion. :)
Hierarchy is a little complex to use from our experience, and the three
cgroups involved in memcg oom can be different: memcg of invoker, killed
task, memcg of going over limit.Suppose a process in B triggers oom and
a victim in root A is selected to be killed, we may as well want to know
memcg stats just local in A cgroup(excludes BCD). So besides hierarchy
info, does it acceptable to also print the local root node stats which
as I did in the V1 version(https://lkml.org/lkml/2012/7/30/179).
Another one I'm hesitating is numa stats, it seems the output is
beginning to get more and more....
Thanks,
Sha
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