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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 3584C100014 X-Stat-Signature: ue8iwtyu18nnsbaxw4ahesu9me5kwiq5 X-Rspam-User: X-HE-Tag: 1736847007-219592 X-HE-Meta: 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 4ZXzMN2V nu6/tiUNcD3Da5V8Qz0zQomYkEFARM0X8i/QR3SRAubEdJaPh4KCAv6egU7CGuOqmtVk2EFggNJLFTeV0zsD7m6ezEtD/GEaNjnYubcMVPzoaoNwCdxjeQqreiNoNqceT4382OoI76GneXywcJM8YKv/lEG4PnOI2W+7yV1rGCCTX/jhE7R/1r+NcPJCvdaSuvVD2LMqntV/Okf48L3WQDZERvLuThWXLwmpjvPaizbgWlWecNkKlR3SlFWBpGfn0V+A0ZJp9a7XENqT543h0/JG/i4i8sKCnKJa+hlWJsPM41mCJWMVjWgryuQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000024, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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