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Mon, 07 Jun 2021 11:51:07 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzAyUl3jh5QUrk9UgJcf2xIvEAWP+/yVr6OZomzEWmLoMcbAnfFWMgB/NQggg1aLvOtjaD19A== X-Received: by 2002:a05:620a:5b5:: with SMTP id q21mr12974248qkq.58.1623091867372; Mon, 07 Jun 2021 11:51:07 -0700 (PDT) Received: from llong.remote.csb ([2601:191:8500:76c0::cdbc]) by smtp.gmail.com with ESMTPSA id 16sm4559409qtt.19.2021.06.07.11.51.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Jun 2021 11:51:06 -0700 (PDT) From: Waiman Long X-Google-Original-From: Waiman Long Subject: Re: [RFC PATCH] mm/oom_kill: allow oom kill allocating task for non-global case To: Shakeel Butt , Waiman Long Cc: Aaron Tomlin , Linux MM , Andrew Morton , Vlastimil Babka , Michal Hocko , LKML References: <20210607163103.632681-1-atomlin@redhat.com> Message-ID: Date: Mon, 7 Jun 2021 14:51:05 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=asY96y7X; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=ZraoQoVU; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf16.hostedemail.com: domain of llong@redhat.com has no SPF policy when checking 216.205.24.124) smtp.mailfrom=llong@redhat.com X-Rspamd-Server: rspam02 X-Stat-Signature: cwkn65q85hf9ykpza3sefbyrwpefyt87 X-Rspamd-Queue-Id: E5E4180192FE X-HE-Tag: 1623099330-3038 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/7/21 2:43 PM, Shakeel Butt wrote: > On Mon, Jun 7, 2021 at 9:45 AM Waiman Long wrote: >> On 6/7/21 12:31 PM, Aaron Tomlin wrote: >>> At the present time, in the context of memcg OOM, even when >>> sysctl_oom_kill_allocating_task is enabled/or set, the "allocating" >>> task cannot be selected, as a target for the OOM killer. >>> >>> This patch removes the restriction entirely. >>> >>> Signed-off-by: Aaron Tomlin >>> --- >>> mm/oom_kill.c | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/mm/oom_kill.c b/mm/oom_kill.c >>> index eefd3f5fde46..3bae33e2d9c2 100644 >>> --- a/mm/oom_kill.c >>> +++ b/mm/oom_kill.c >>> @@ -1089,9 +1089,9 @@ bool out_of_memory(struct oom_control *oc) >>> oc->nodemask = NULL; >>> check_panic_on_oom(oc); >>> >>> - if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task && >>> - current->mm && !oom_unkillable_task(current) && >>> - oom_cpuset_eligible(current, oc) && >>> + if (sysctl_oom_kill_allocating_task && current->mm && >>> + !oom_unkillable_task(current) && >>> + oom_cpuset_eligible(current, oc) && >>> current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) { >>> get_task_struct(current); >>> oc->chosen = current; >> To provide more context for this patch, we are actually seeing that in a >> customer report about OOM happened in a container where the dominating >> task used up most of the memory and it happened to be the task that >> triggered the OOM with the result that no killable process could be >> found. > Why was there no killable process? What about the process allocating > the memory or is this remote memcg charging? It is because the other processes have a oom_adjust_score of -1000. So they are non-killable. Anyway, they don't consume that much memory and killing them won't free up that much. The other process that uses most of the memory is the one that trigger the OOM kill in the first place because the memory limit has been reached in new memory allocation. Based on the current logic, this process cannot be killed at all even if we set the oom_kill_allocating_task to 1 if the OOM happens only within the memcg context, not in a global OOM situation. This patch is to allow this process to be killed under this circumstance. Cheers, Longman