From: Zhaoyang Huang <huangzhaoyang@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1] ringbuffer: Don't choose the process with adj equal OOM_SCORE_ADJ_MIN
Date: Tue, 10 Apr 2018 10:32:36 +0800 [thread overview]
Message-ID: <CAGWkznEuGCZq600XjCtp3hzgN2LrCgwSAfoLwQR7jTw5p=qHoQ@mail.gmail.com> (raw)
In-Reply-To: <CAGWkznEhy7Fard=6E3X_qUezXd33RdKV9CVeONWL=6EQ1bokEw@mail.gmail.com>
On Tue, Apr 10, 2018 at 8:32 AM, Zhaoyang Huang <huangzhaoyang@gmail.com> wrote:
> On Mon, Apr 9, 2018 at 9:49 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
>> On Mon, 9 Apr 2018 08:56:01 +0800
>> Zhaoyang Huang <huangzhaoyang@gmail.com> wrote:
>>
>>> >>
>>> >> if (oom_task_origin(task)) {
>>> >> points = ULONG_MAX;
>>> >> goto select;
>>> >> }
>>> >>
>>> >> points = oom_badness(task, NULL, oc->nodemask, oc->totalpages);
>>> >> if (!points || points < oc->chosen_points)
>>> >> goto next;
>>> >
>>> > And what's wrong with that?
>>> >
>>> > -- Steve
>>> I think the original thought of OOM is the flag 'OOM_SCORE_ADJ_MIN' is
>>> most likely to be set by process himself via accessing the proc file,
>>> if it does so, OOM can select it as the victim. except, it is
>>> reluctant to choose the critical process to be killed, so I suggest
>>> not to set such heavy flag as OOM_SCORE_ADJ_MIN on behalf of -1000
>>> process.
>>
>> Really, I don't think tasks that are setting OOM_CORE_ADJ_MIN should be
>> allocating a lot of memory in the kernel (via ring buffer). It sounds
>> like a good way to wreck havoc on the system.
>>
>> It's basically saying, "I'm going to take up all memory, but don't kill
>> me, just kill some random user on the system".
>>
>> -- Steve
> Sure, but the memory status is dynamic, the process could also exceed the limit
> at the moment even it check the available memory before. We have to
> add protection
> for such kind of risk. It could also happen that the critical process
> be preempted by
> another huge memory allocating process, which may cause insufficient memory when
> it schedule back.
For bellowing scenario, process A have no intension to exhaust the
memory, but will be likely to be selected by OOM for we set
OOM_CORE_ADJ_MIN for it.
process A(-1000) process B
i = si_mem_available();
if (i < nr_pages)
return -ENOMEM;
schedule
--------------->
allocate huge memory
<-------------
if (user_thread)
set_current_oom_origin();
for (i = 0; i < nr_pages; i++) {
bpage = kzalloc_node
next prev parent reply other threads:[~2018-04-10 2:32 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-08 2:16 [PATCH v1] ringbuffer: Don't choose the process with adj equal OOM_SCORE_ADJ_MIN Zhaoyang Huang
2018-04-08 3:48 ` Steven Rostedt
2018-04-08 5:54 ` Zhaoyang Huang
2018-04-08 12:47 ` Steven Rostedt
2018-04-09 0:56 ` Zhaoyang Huang
2018-04-09 13:49 ` Steven Rostedt
2018-04-10 0:32 ` Zhaoyang Huang
2018-04-10 2:32 ` Zhaoyang Huang [this message]
2018-04-10 3:12 ` Steven Rostedt
2018-04-10 3:41 ` Zhaoyang Huang
2018-04-10 6:14 ` Michal Hocko
2018-04-10 6:39 ` Zhaoyang Huang
2018-04-10 7:49 ` Michal Hocko
2018-04-10 8:04 ` Zhaoyang Huang
2018-04-10 8:12 ` Michal Hocko
2018-04-10 8:38 ` Zhaoyang Huang
2018-04-10 9:01 ` Michal Hocko
2018-04-10 9:32 ` Zhaoyang Huang
2018-04-10 9:51 ` Zhaoyang Huang
2018-04-10 10:49 ` Michal Hocko
2018-04-10 12:23 ` Steven Rostedt
2018-04-10 12:27 ` Michal Hocko
2018-04-10 12:36 ` Steven Rostedt
2018-04-10 13:13 ` Steven Rostedt
2018-04-10 13:14 ` Steven Rostedt
2018-04-10 16:45 ` Joel Fernandes
2018-04-10 18:00 ` Steven Rostedt
2018-04-10 18:39 ` Joel Fernandes
2018-04-10 19:05 ` Steven Rostedt
2018-04-11 7:48 ` Zhaoyang Huang
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