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[91.43.71.253]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-487243cede9sm1480767f8f.0.2026.09.18.13.45.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Sep 2026 13:45:25 -0700 (PDT) Message-ID: <8c3677b0-4def-42d8-989f-b0934c686f6f@googlemail.com> Date: Fri, 18 Sep 2026 22:45:24 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Betterbird (Windows) Subject: Re: [PATCH 6.12 0000/1102] 6.12.111-rc1 review To: Sasha Levin , Brett A C Sheffield , Greg Kroah-Hartman Cc: stable@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, linux@roeck-us.net, shuah@kernel.org, patches@kernelci.org, lkft-triage@lists.linaro.org, pavel@nabladev.com, jonathanh@nvidia.com, f.fainelli@gmail.com, sudipm.mukherjee@gmail.com, rwarsow@gmx.de, conor@kernel.org, hargar@microsoft.com, broonie@kernel.org, achill@achill.org, sr@sladewatkins.com References: <20260917151539.408551884@linuxfoundation.org> <0dc35fd5-ee4c-4140-b154-78a49981ddb7@googlemail.com> <1e80f4b3-3919-4568-aabd-f0172581831d@googlemail.com> <20260918151140.2101477305-sashal@kernel.org> Content-Language: de-DE From: Peter Schneider In-Reply-To: <20260918151140.2101477305-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Am 18.09.2026 um 17:54 schrieb Sasha Levin: > On Fri, Sep 18, 2026 at 07:49:48AM +0200, Peter Schneider wrote: >> So I have bisected this warning, and the first bad commit is >> >> [af5775004c9c02f37be06d2035a056b6abb1cb6c] sched/fair: Fix EEVDF entity >> placement bug causing scheduling lag > > Thank you - a second bisect on top of a reverted tree is real work, and > it was the right call. Dropped from the 6.12 queue: > > 6d71a9c61604 ("sched/fair: Fix EEVDF entity placement bug causing > scheduling lag") > >> Trying to revert this from 6.12.111-rc1 however resulted in some >> conflicts I was unable to resolve. There are other dependencies like: > > Right, which is why the three patches stacked on top of it came out at > the same time: > > 6e3c0a4e1ad1 ("sched/fair: Fix lag clamp") > 51b0e68cfa0a ("sched/eevdf: Fix rb augmented with multi fields") > 9a8bc9bb4c3f ("sched/eevdf: Fix augmented max_slice") Ah ok, that third one I missed, so it didn't work out for me. > Some background on why this only bites 6.12: the WARN_ON_ONCE(!load) you hit > needs 4423af84b297 ("sched/fair: optimize the PLACE_LAG when se->vlag is zero") > and c70fc32f4443 ("sched/fair: Adhere to place_entity() constraints", which is > a Fixes: for exactly this commit) to be shut up, and 6.12 has neither. More to > the point, upstream has since reverted 6d71a9c61604 outright - 101f3498b4bd > ("sched/fair: Revert 6d71a9c61604 ...") from January, which concludes the > original commit "was wrong!" because avg_vruntime() already accounts for > cfs_rq->curr when it is on_rq. 6.12 only ever picked it up as a dependency of > the eevdf fixes above, so carrying placement math that mainline has disowned is > not something we want here. Sounds complicated; no wonder I was unable to figure this out on my own. Beste Grüße, Peter Schneider -- Climb the mountain not to plant your flag, but to embrace the challenge, enjoy the air and behold the view. Climb it so you can see the world, not so the world can see you. -- David McCullough Jr. OpenPGP: 0xA3828BD796CCE11A8CADE8866E3A92C92C3FF244 Download: https://www.peters-netzplatz.de/download/pschneider1968_pub.asc https://keys.mailvelope.com/pks/lookup?op=get&search=pschneider1968@googlemail.com https://keys.mailvelope.com/pks/lookup?op=get&search=pschneider1968@gmail.com