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[109.81.84.135]) by smtp.gmail.com with UTF8SMTPSA id 4fb4d7f45d1cf-5de4d250084sm9533100a12.16.2025.02.12.03.58.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Feb 2025 03:58:14 -0800 (PST) Date: Wed, 12 Feb 2025 12:58:13 +0100 From: Michal Hocko To: Vlastimil Babka Cc: Chen Ridong , akpm@linux-foundation.org, hannes@cmpxchg.org, yosryahmed@google.com, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, davidf@vimeo.com, mkoutny@suse.com, paulmck@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, chenridong@huawei.com, wangweiyang2@huawei.com Subject: Re: [PATCH] mm/oom_kill: revert watchdog reset in global OOM process Message-ID: References: <20250212025707.67009-1-chenridong@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1A9B31C000A X-Stat-Signature: xyinu4hw9o39inyr7hcqsmrseuh4rocn X-HE-Tag: 1739361495-654204 X-HE-Meta: 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 fiHn0SZe QrKc6hfcaUTwceJGNbnrzuGvQY0xtpDKr0bEBniRoVO9sMRX6jfusfcTMd7A2837kYv1/fL471C1ovlulRFgL9+0yCYTkwbaLoZiR+zi+h4j2m1M8oU6qpvbMEzXHE/cjx6v1Vl85CstAdAIcD0ac1gjDEwulO7+a96GKwCs/SbHgSC73cu3j9TBdNKGLymJT925MakMsrscmJActZX7n5InXHi+zgjW1QD9629gm9hPtc2Tcdn0cKipjZrBldwFNESh9wqBWnsB7NWF966PJA7H9MRWmQshrEdZz5ojHJP3Qd4b0ARR7qSkwLjpnofiJb/SZDHd9NUY6qpimw0TprgrF8Jep2A4qDstCVvo+xSiJsK0rEcyMG1uenwX7O0WQ+O5m3Fcc2FNxj3Mf520b1ovEZaoscMam7aEeEjeeTNI+LDeQEyCCY6o15w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, 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 Wed 12-02-25 10:34:06, Vlastimil Babka wrote: > On 2/12/25 10:19, Chen Ridong wrote: > > > > > > On 2025/2/12 16:57, Michal Hocko wrote: > >> On Wed 12-02-25 02:57:07, Chen Ridong wrote: > >>> From: Chen Ridong > >>> > >>> Unlike memcg OOM, which is relatively common, global OOM events are rare > >>> and typically indicate that the entire system is under severe memory > >>> pressure. The commit ade81479c7dd ("memcg: fix soft lockup in the OOM > >>> process") added the touch_softlockup_watchdog in the global OOM handler to > >>> suppess the soft lockup issues. However, while this change can suppress > >>> soft lockup warnings, it does not address RCU stalls, which can still be > >>> detected and may cause unnecessary disturbances. Simply remove the > >>> modification from the global OOM handler. > >>> > >>> Fixes: ade81479c7dd ("memcg: fix soft lockup in the OOM process") > >> > >> But this is not really fixing anything, is it? While this doesn't > >> address a potential RCU stall it doesn't address any actual problem. > >> So why do we want to do this? > >> > > > > > > [1] > > https://lore.kernel.org/cgroups/0d9ea655-5c1a-4ba9-9eeb-b45d74cc68d0@huaweicloud.com/ > > > > As previously discussed, the work I have done on the global OOM is 'half > > of the job'. Based on our discussions, I thought that it would be best > > to abandon this approach for global OOM. Therefore, I am sending this > > patch to revert the changes. > > > > Or just leave it? > > I suggested that part doesn't need to be in the patch, but if it was merged > with it, we can just leave it there. Thanks. Agreed! -- Michal Hocko SUSE Labs