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Wed, 04 Dec 2024 00:01:43 -0800 (PST) X-Google-Smtp-Source: AGHT+IEhiXpMva47idGqFj5GtbBNZmdu1R1vo3wasWbHy6+dTkb4iz+yeUGZIRXwuzqkuGPteOIYbg== X-Received: by 2002:a05:6214:2aad:b0:6d8:8fdd:9791 with SMTP id 6a1803df08f44-6d8b73b65eemr99367886d6.25.1733299303243; Wed, 04 Dec 2024 00:01:43 -0800 (PST) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.35]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d8afe44481sm25181916d6.72.2024.12.04.00.01.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2024 00:01:42 -0800 (PST) Message-ID: <81cc8be1b5fe76a3323c2990994442f7e7959629.camel@redhat.com> Subject: Re: [PATCH 2/2] sched: Move task_mm_cid_work to RCU callback From: Gabriele Monaco To: Joel Fernandes , Mathieu Desnoyers Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org, paulmck , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Boqun Feng , Uladzislau Rezki , Lai Jiangshan , Zqiang , "rcu@vger.kernel.org" Date: Wed, 04 Dec 2024 09:01:36 +0100 In-Reply-To: References: <20241202140735.56368-1-gmonaco@redhat.com> <20241202140735.56368-3-gmonaco@redhat.com> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.2 (3.54.2-1.fc41) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2024-12-03 at 10:00 -0500, Joel Fernandes wrote: >=20 > Also there is no guarantee that RCU callback will run within a thread > context (example, some configurations run it in softirq). Further, > call_rcu() usage as shown in this patch can also delay callback runs > by seconds (with RCU_LAZY enabled). >=20 > See also #5 in checklist: https://docs.kernel.org/RCU/checklist.html >=20 Thanks for the tips, I get the RCU callbacks are clearly not the right place where to put this function. I'm working on a V2 where the same tick is scheduling a new work_struct in the mm_struct instead, let's see where that brings. Thanks all for the constructive comments. Gabriele