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[109.81.84.135]) by smtp.gmail.com with UTF8SMTPSA id a640c23a62f3a-ab78d5771easm947387866b.83.2025.02.11.12.35.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Feb 2025 12:35:48 -0800 (PST) Date: Tue, 11 Feb 2025 21:35:47 +0100 From: Michal Hocko To: Shakeel Butt Cc: Chen Ridong , hannes@cmpxchg.org, roman.gushchin@linux.dev, muchun.song@linux.dev, akpm@linux-foundation.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, chenridong@huawei.com, wangweiyang2@huawei.com Subject: Re: [PATCH] memcg: avoid dead loop when setting memory.max Message-ID: References: <20250211081819.33307-1-chenridong@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: oq3jqwxpdx8tswpiz3xpfu95cbqg9e36 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5B2CF4000E X-HE-Tag: 1739306150-364725 X-HE-Meta: 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 7Udk0neE 6jkxRvLcG44Y2jpfwonF054ecxDuw3Qb4DdYBWCO7RNfFCa907h+fZWeqNRCWv4nDZnNZGnmIlBzgA0BEAKM6F9+wWrfgdlR0XDISoSDd/FHgjAS4vklSKBdbdGRlhQM8Wfo3Og+xXkdC31rfJURw+ZwE67Au+bba9CZ70aWLr1KHr2umqNIApu6qGs+UDQxxwfto//V2qKtQhYbs5ogfiZOiKeUO3ztxoi5NwzY1rBVk0UvjFqI5Gb7dUqanXOKkpUg2+s62G8N/KF7AZHTHZP70ndUpcBDjYyNPcKNTBpiL6/IV2VwQuKEnQIWJgYpaydfd X-Bogosity: Ham, tests=bogofilter, spamicity=0.000027, 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 11-02-25 11:04:21, Shakeel Butt wrote: > On Tue, Feb 11, 2025 at 08:18:19AM +0000, Chen Ridong wrote: [...] > Wouldn't it be more robust if we put an upper bound on the else case of > above condition i.e. fix number of retries? As you have discovered there > is a hidden dependency on the forward progress of oom_reaper and this > check/code-path which I think is not needed. Any OOM path has a dependency on oom_reaper or task exiting. Is there any reason why this path should be any special? With cond_resched we can look for a day where this will be just removed and the code will still work. With a number of retries we will have a non-deterministic time dependent behavior because number of retries rather than fwd progress would define the failure mode. -- Michal Hocko SUSE Labs