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[82.17.115.212]) by smtp.gmail.com with ESMTPSA id z17sm3160152wrt.60.2021.06.16.13.18.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 13:18:31 -0700 (PDT) Date: Wed, 16 Jun 2021 21:18:31 +0100 From: Aaron Tomlin To: Michal Hocko Cc: linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, penguin-kernel@i-love.sakura.ne.jp, llong@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/oom_kill: show oom eligibility when displaying the current memory state of all tasks Message-ID: <20210616201831.m6el3lob3eizwd3t@ava.usersys.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 References: <20210612204634.1102472-1-atomlin@redhat.com> <20210615115147.gp3w5bcjoaarvyse@ava.usersys.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="cp2wvemzhtrrjjju" Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --cp2wvemzhtrrjjju Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue 2021-06-15 14:42 +0200, Michal Hocko wrote: > This is all true but it is not really clear why that is really a > problem. Kernel log already contains information about reaped processes > as they are reported to the log. I fully acknowledge that this is rather > spartan but on the other hand from years of experience reading oom > reports I have to say the dump_tasks is the least interesting part of > the report (while being the most verbose one). I understand. I suppose, in a situation whereby dump_tasks() output is only available, for whatever reason, it can provide at least some insight into what tasks were actually considered not OOM eligible and why. > All that being said, I am not really opposing extending the information > although I am a bit worried about leaking too much internal state to the > log. Fair enough. That said, I still feel highlighting such "ineligible" tasks could be useful to the viewer for troubleshooting purposes; we already display OOM_SCORE_ADJ_MIN. Consider a situation when only a few tasks in a memcg are displayed as possibly OOM eligible but one had MMF_OOM_SKIP applied. In my opinion, perhaps it is better to just exclude such details altogether. That being said, as you know, we only provide this facility when one is interested in it anyway i.e., if oom_dump_tasks is enabled. > What I am asking for here is a justification why this addition is a > general improvement and how it helps uderstanding oom reports further. > So please focus on that part. Sure; albeit, thinking about this more, it does not provide much understanding in simple isolation. Kind regards, --=20 Aaron Tomlin --cp2wvemzhtrrjjju Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEeQaE6/qKljiNHm6b4t6WWBnMd9YFAmDKXI0ACgkQ4t6WWBnM d9YqOg//ZJvwyHkB4rdF2yXUBIz2+Ud8O2L9hlvNQ4CpBQ83o/EKchB7cznvf3X7 s3w7As7WaLZJYt3JMWdHj4L+QLGS2Zf9QIBFYtcLrW/jo0fR2hia5bpms8FsPQxQ BvA2RavUDTSPlyz/xkUF0vV5tf+c7YI6qAFu2HPw5IWwnYHQXjGwcgNeWsKnVAZs nPh1VMUm0Xjw0NyQlgHqvQr1o85eVAyQGaO+ro+EgDZJCPrdeBsYHZErOXUnL2gd HdaOItt5W1UKfDFbJ3i8wUr/SpvQxkWUmDzv2cchDV5nQ3RpkT1uwrw0egu7CbDZ WBV/P8Ckodf03yIvmD5MQsKHGmcvf8/craWyOprb1Xl+hOC6QMT3pJz2LdmMiUvp l8P0KuiFu1MwCytHbcPGhN1ZO0pg4hMg+gRl2xReu7X6DPFfi/BSkIDt/RcStzYS 829o4UY6rk0uobB1lHo8IQHKr6AarwLK0PcjxmpvrULgXDE9beFTN6ISJJMFZeWV rmsKDluSHkZIRETs7XFvzJGetIMY1xjTQxFG0PzGWJJSsABgYf7+NZA7FqizNVUO c35i6YTqs2yLbYv7kvkMvw72uTm441jlyw4M+LktxMOc/AfBdvWZUAI9NBBbzYpc CXPhLrtTqGgcUV2WjHsYJIC2qWRZWldttmzEEuWCqbIzNXbAYzk= =/GLJ -----END PGP SIGNATURE----- --cp2wvemzhtrrjjju--