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Tue, 28 Jan 2025 12:46:09 +0100 Message-ID: Subject: Re: [PATCH 6.12 000/122] 6.12.11-rc1 review From: Mike Galbraith To: Ron Economos , Peter Zijlstra , Arnd Bergmann Cc: Naresh Kamboju , Greg Kroah-Hartman , stable@vger.kernel.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Guenter Roeck , shuah , patches@kernelci.org, lkft-triage@lists.linaro.org, Pavel Machek , Jon Hunter , Florian Fainelli , Sudip Mukherjee , srw@sladewatkins.net, rwarsow@gmx.de, Conor Dooley , hargar@microsoft.com, Mark Brown , Anders Roxell , Vincent Guittot , Dan Carpenter Date: Tue, 28 Jan 2025 12:46:07 +0100 In-Reply-To: References: <20250121174532.991109301@linuxfoundation.org> <20250122105949.GK7145@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:LNd3PNtVtBWcaN0qY6J2BQCF9cxhKokTA2IeDesDglvUGDt3Qjs 0zC827kqaRKoRzQWzfQttSjwySiBD9JHxtD9AAMWt1bVDIv9x21wODFzJsywbv5fnR8hJRb T1n37+XOLRSLcMTQ3XSySTYbrnfjvJDlOtrhihTNXxV7TMIwPSqwwWJiLffqzkY9HGOjCGo epHlDMCyO9AhMfKmKJZNg== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:Mx5CRPGPBrI=;TL8UPd/L2cg5suTaAQbInBWk8kw K9G0OSYscgZ5rM++qcOh1ug89flTbw34+Ei94xcjXgnBFEIx4AfbLbzECkKk5qn4nIfD/6zqq IevWCQIoIF7qF2d0yOSUxh1ltU/tvLWWa2KrJUU0p31sUtmFomRvV6s2t9TKJwJeMU5TmeCgt XbxKVzET0EGTajLQQjHh7I1rTl8klxgNBHiSx/nuT5OdaSDc4aF9JEkw4V6kVHH+pMI1hHn1H WD8vgXP7NFaswB5Q5JTNZNOV1zj+LefJ40bA6UyOGPTEsovgMjfazBlny+Dp51pu/5czBXONC jyvBd28B7J3739tS4MX1ys9L8/8vjdxsT8D6MgAw5etM1PG9mBk5I+TXu+aOHEmxgwhe+ux0s N7BgSXGRKTyjJaRVymh1OHeYp861W6AREK4xOqU8hjRBd7XCtvuEe1dnF7U8HGwCaNibZx97S r1ZJqcBOdEvbEoO8uivGAefZp45Enz5MvnhkqqqSJivl1EeEbdYD7zmINdspHFuu5cdxavlRQ QNhxCeskmue9II/HbSd4wtcx9dR9+1kSPEp6i/zhQlk/W0GBnRiGX8H8dzeMhISTFc+lytb+a UTYb6xLfV83pk0oxFIVur4OL1oif94dr2iBVtcNembR5943soJhjJ6wYVxY5YBGz8UmA8gr64 xoIA2OCz28t/WwmyzisilDDONszDLaPY9jgkKqgyIenA6ts1bGcJUix+dSdxnu4cGipYq9W8s eMMDLK/Bux37PpCpWHfDKlj3F7FRn42TVBccjGe7JfBAF4LnkZe9MF9cwpbXI+tZyo1gjmga3 GQRVZCr5WWuFNBCwinrIgmq0Keq11V42F6o4WOQqzsphRRhoUGJqYHt2l1aLPC0tf6SezzZNq hy+I9duvYGulLF3yfkmHHZ2W0bOz/w7erpFDvmdPijN2OMULLgC/IgAO8TZ9gPwKGHnC/c9Rt MSz/l2+UMQOi8GtYxAkPQCYXRMLu2T/4c7jflR1CtK8bXRYIdCMq7DnRrPJsN17DBZ12imK/h 69a0CSURzp8bOIbjZjwsckaY4ucAj4NTrom9rzPUixq9LZWH3sgYsAo6W6CS3XZOpc1y8JiVn HvDL9EVUPAmRRSWZaggyl0nsAiXYkOycbYv5oPqeUstn8YsCi2aY+222lotX0vRHaxZdg9jlN M39yjrT8VDqSozlZIE0sHJxUag23a5moTCXCysnSr6w== On Wed, 2025-01-22 at 03:11 -0800, Ron Economos wrote: > On 1/22/25 02:59, Peter Zijlstra wrote: > > On Wed, Jan 22, 2025 at 11:56:13AM +0100, Arnd Bergmann wrote: > > > On Wed, Jan 22, 2025, at 11:04, Naresh Kamboju wrote: > > > > On Tue, 21 Jan 2025 at 23:28, Greg Kroah-Hartman > > > > wrote: > > > > 0000000000000000 > > > > <4>[=C2=A0 160.712071] Call trace: > > > > <4>[ 160.712597] place_entity (kernel/sched/fair.c:5250 (discrimin= ator 1)) > > > > <4>[ 160.713221] reweight_entity (kernel/sched/fair.c:3813) > > > > <4>[ 160.713802] update_cfs_group (kernel/sched/fair.c:3975 (discr= iminator 1)) > > > > <4>[ 160.714277] dequeue_entities (kernel/sched/fair.c:7091) > > > > <4>[ 160.714903] dequeue_task_fair (kernel/sched/fair.c:7144 (disc= riminator 1)) > > > > <4>[ 160.716502] move_queued_task.isra.0 (kernel/sched/core.c:2437 > > > > (discriminator 1)) > > > I don't see anything that immediately sticks out as causing this, > > > but I do see five scheduler patches backported in stable-rc > > > on top of v6.12.8, these are the original commits: > > > > > > 66951e4860d3 ("sched/fair: Fix update_cfs_group() vs DELAY_DEQUEUE") > > This one reworks reweight_entity(), but I've been running with that on > > top of 13-rc6 for a week or so and not seen this. > > The offending commit is 6d71a9c6160479899ee744d2c6d6602a191deb1f > "sched/fair: Fix EEVDF entity placement bug causing scheduling lag" > > It works fine on 6.13, at least on RISC-V (which is the only arch I test= ). Seems 6.13 is gripe free thanks to it containing 4423af84b297. I stumbled upon a reproducer for my x86_64 desktop box: all I need do is fire up a kvm guest in an enterprise configured host. That inspires libvirt goop to engage group scheduling, splat follows instantly. Back 4423af84b297 out of 6.13, it starts griping, add it to a 6.12 tree containing 6d71a9c61604, it stops doing so. > It's already been reverted and 6.12.11-rc2 has been pushed out. So stable should perhaps take 4423af84b297 along with 6d71a9c61604? -Mike