From: Michal Hocko <mhocko@kernel.org>
To: Joel Fernandes <joelaf@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>,
Zhaoyang Huang <huangzhaoyang@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
kernel-patch-test@lists.linaro.org,
Andrew Morton <akpm@linux-foundation.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH] ring-buffer: Add set/clear_current_oom_origin() during allocations
Date: Thu, 5 Apr 2018 16:51:59 +0200 [thread overview]
Message-ID: <20180405145159.GM6312@dhcp22.suse.cz> (raw)
In-Reply-To: <CAJWu+opM6RjK-Z1dr35XvQ5cLKaV=cLG5uMu-rLkoO=X03c+FA@mail.gmail.com>
On Wed 04-04-18 16:59:18, Joel Fernandes wrote:
> Hi Steve,
>
> On Wed, Apr 4, 2018 at 9:18 AM, Joel Fernandes <joelaf@google.com> wrote:
> > On Wed, Apr 4, 2018 at 9:13 AM, Steven Rostedt <rostedt@goodmis.org> wrote:
> > [..]
> >>>
> >>> Also, I agree with the new patch and its nice idea to do that.
> >>
> >> Thanks, want to give it a test too?
>
> With the latest tree and the below diff, I can still OOM-kill a victim
> process doing a large buffer_size_kb write:
>
> I pulled your ftrace/core and added this:
> + /*
> i = si_mem_available();
> if (i < nr_pages)
> return -ENOMEM;
> + */
>
> Here's a run in Qemu with 4-cores 1GB total memory:
>
> bash-4.3# ./m -m 1M &
> [1] 1056
> bash-4.3#
> bash-4.3#
> bash-4.3#
> bash-4.3# echo 10000000 > /d/tracing/buffer_size_kb
> [ 33.213988] Out of memory: Kill process 1042 (bash) score
> 1712050900 or sacrifice child
> [ 33.215349] Killed process 1056 (m) total-vm:9220kB,
> anon-rss:7564kB, file-rss:4kB, shmem-rss:640kB
OK, so the reason your memory hog is triggered is that your echo is
built-in and we properly select bask as an oom_origin but then another
clever heuristic jumps in and tries to reduce the damage by sacrificing
a child process. And your memory hog runs as a child from the same bash
session.
I cannot say I would love this heuristic. In fact I would really love to
dig it deep under the ground. But this is a harder sell than it might
seem. Anyway is your testing scenario really representative enough to
care? Does the buffer_size_kb updater runs in the same process as any
large memory process?
> bash: echo: write error: Cannot allocate memory
> [1]+ Killed ./m -m 1M
> bash-4.3#
> --
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2018-04-05 14:52 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 15:53 [PATCH] ring-buffer: Add set/clear_current_oom_origin() during allocations Steven Rostedt
2018-04-04 16:00 ` Steven Rostedt
2018-04-04 16:03 ` Joel Fernandes
2018-04-04 16:13 ` Steven Rostedt
2018-04-04 16:18 ` Joel Fernandes
2018-04-04 23:59 ` Joel Fernandes
2018-04-05 13:43 ` Steven Rostedt
2018-04-05 19:57 ` Joel Fernandes
2018-04-05 23:36 ` Joel Fernandes
2018-04-06 7:16 ` Zhaoyang Huang
2018-04-05 14:51 ` Michal Hocko [this message]
2018-04-05 19:47 ` Joel Fernandes
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