From: Nico Pache <npache@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Rafael Aquini <aquini@redhat.com>,
Waiman Long <longman@redhat.com>, Baoquan He <bhe@redhat.com>,
Christoph von Recklinghausen <crecklin@redhat.com>,
Don Dutile <ddutile@redhat.com>,
"Herton R . Krzesinski" <herton@redhat.com>,
David Rientjes <rientjes@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Ingo Molnar <mingo@redhat.com>, Joel Savitz <jsavitz@redhat.com>,
Darren Hart <dvhart@infradead.org>,
stable@kernel.org
Subject: Re: [PATCH v8] oom_kill.c: futex: Don't OOM reap the VMA containing the robust_list_head
Date: Fri, 8 Apr 2022 06:36:40 -0400 [thread overview]
Message-ID: <2293c547-3878-435a-ec1c-854c3181ad14@redhat.com> (raw)
In-Reply-To: <YlAHfU7VEI0wYAb/@dhcp22.suse.cz>
On 4/8/22 05:59, Michal Hocko wrote:
> On Fri 08-04-22 05:40:09, Nico Pache wrote:
>>
>>
>> On 4/8/22 05:36, Michal Hocko wrote:
>>> On Fri 08-04-22 04:52:33, Nico Pache wrote:
>>> [...]
>>>> In a heavily contended CPU with high memory pressure the delay may also
>>>> lead to other processes unnecessarily OOMing.
>>>
>>> Let me just comment on this part because there is likely a confusion
>>> inlved. Delaying the oom_reaper _cannot_ lead to additional OOM killing
>>> because the the oom killing is throttled by existence of a preexisting
>>> OOM victim. In other words as long as there is an alive victim no
>>> further victims are not selected and the oom killer backs off. The
>>> oom_repaer will hide the alive oom victim after it is processed.
>>> The longer the delay will be the longer an oom victim can block a
>>> further progress but it cannot really cause unnecessary OOMing.
>> Is it not the case that if we delay an OOM, the amount of available memory stays
>> limited and other processes that are allocating memory can become OOM candidates?
>
> No. Have a look at oom_evaluate_task (tsk_is_oom_victim check).
Ok I see.
Doesnt the delay then allow the system to run into the following case more easily?:
pr_warn("Out of memory and no killable processes...\n");
panic("System is deadlocked on memory\n");
If the system cant select another OOM candidate, the oom_reaper is delayed, and
the exit is blocked, then we panic.
-- Nico
next prev parent reply other threads:[~2022-04-08 10:36 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-08 3:28 [PATCH v8] oom_kill.c: futex: Don't OOM reap the VMA containing the robust_list_head Nico Pache
2022-04-08 8:15 ` Peter Zijlstra
2022-04-08 8:37 ` Thomas Gleixner
2022-04-08 8:52 ` Nico Pache
2022-04-08 9:36 ` Michal Hocko
2022-04-08 9:40 ` Nico Pache
2022-04-08 9:59 ` Michal Hocko
2022-04-08 10:36 ` Nico Pache [this message]
2022-04-08 10:51 ` Michal Hocko
2022-04-08 11:26 ` Nico Pache
2022-04-08 11:48 ` Michal Hocko
2022-04-08 8:41 ` Nico Pache
2022-04-08 13:54 ` Thomas Gleixner
2022-04-08 16:13 ` Joel Savitz
2022-04-08 21:41 ` Thomas Gleixner
2022-04-11 6:48 ` Michal Hocko
2022-04-11 7:47 ` Thomas Gleixner
2022-04-11 9:08 ` Michal Hocko
2022-04-12 0:02 ` Nico Pache
2022-04-13 16:00 ` Nico Pache
2022-04-11 23:51 ` Nico Pache
2022-04-12 16:20 ` Thomas Gleixner
2022-04-12 17:03 ` Nico Pache
2022-04-08 14:41 ` kernel test robot
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