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[109.81.90.202]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-436e2dc0069sm205545485e9.11.2025.01.14.01.30.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jan 2025 01:30:06 -0800 (PST) Date: Tue, 14 Jan 2025 10:30:05 +0100 From: Michal Hocko To: Vlastimil Babka Cc: Andrew Morton , Chen Ridong , hannes@cmpxchg.org, yosryahmed@google.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, davidf@vimeo.com, handai.szj@taobao.com, rientjes@google.com, kamezawa.hiroyu@jp.fujitsu.com, RCU , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, chenridong@huawei.com, wangweiyang2@huawei.com Subject: Re: [PATCH v3] memcg: fix soft lockup in the OOM process Message-ID: References: <20241224025238.3768787-1-chenridong@huaweicloud.com> <1ea309c1-d0f8-4209-b0b0-e69ad4e986ae@suse.cz> <58caaa4f-cf78-4d0f-af31-8a9277b6ebf5@huaweicloud.com> <20250113194546.3de1af46fa7a668111909b63@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue 14-01-25 10:20:28, Vlastimil Babka wrote: > On 1/14/25 09:40, Michal Hocko wrote: > > On Mon 13-01-25 19:45:46, Andrew Morton wrote: [...] > >> > For global OOM, system is likely to struggle, do we have to do some > >> > works to suppress RCU detete? > >> > >> rcu_cpu_stall_reset()? > > > > Do we really care about those? The code to iterate over all processes > > under RCU is there (basically) since ever and yet we do not seem to have > > many reports of stalls? Chen's situation is specific to memcg OOM and > > touching the global case was mostly for consistency reasons. > > Then I'd rather not touch the global case then if it's theoretical? No strong opinion on this on my side. The only actual reason touch_softlockup_watchdog is there is becuase it originally had incorrectly cond_resched there. If half silencing (soft lock up detector only) disturbs people then let's just drop that hunk. -- Michal Hocko SUSE Labs