From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out28-57.mail.aliyun.com (out28-57.mail.aliyun.com [115.124.28.57]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5A431DFF7 for ; Wed, 31 Dec 2025 00:16:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.28.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767140201; cv=none; b=NIaDyPjDa1NQoOTR2DcRMf9UiJlus8vaK0i88TbShqIlfO+xnM6KY0yFDl76P3IjVkRswL88lEB6EtZ4ThCuPh450fcfJU/OeY6cM2FQpJRBB05inzX55qpqUJBcInUaNXd+saR/s/KXkDZGb6AYXuvAtApBYZsBPrUV7AfGKFA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767140201; c=relaxed/simple; bh=cGPiFRsGnGe6pQMZmqA+UFqZ8dPYV+Iz+mw3RT6qpqc=; h=Date:From:To:Subject:Cc:In-Reply-To:References:Message-Id: MIME-Version:Content-Type; b=QWHdcPdS0MTXDzHEj3jxowrE/B+10KBEgsCsEksfQdwOSNA7vP4HnTOJhM2UaSJraFx6uAqC1FWe99Hikh+CbTDpTXuc/xOiIu2tJ0lP+CptphfRmvnc5ki/7UMVUN5TuMIuHUQJS2MGPijV7PgxeVhCHZkDAOxo/t23TYX8bnw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=e16-tech.com; spf=pass smtp.mailfrom=e16-tech.com; arc=none smtp.client-ip=115.124.28.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=e16-tech.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=e16-tech.com Received: from 192.168.2.112(mailfrom:wangyugui@e16-tech.com fp:SMTPD_---.fwkMib8_1767138342 cluster:ay29) by smtp.aliyun-inc.com; Wed, 31 Dec 2025 07:45:43 +0800 Date: Wed, 31 Dec 2025 07:45:44 +0800 From: Wang Yugui To: Holger Hoffst?tte Subject: Re: Please add 127b90315ca0 ("sched/proxy: Yield the donor task") to 6.12.y / 6.18.y Cc: "stable@vger.kernel.org" , Greg KH , Sasha Levin , Fernand Sieber In-Reply-To: <04b82346-c38a-08e2-49d5-d64981eb7dae@applied-asynchrony.com> References: <04b82346-c38a-08e2-49d5-d64981eb7dae@applied-asynchrony.com> Message-Id: <20251231074543.64FC.409509F4@e16-tech.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 8bit X-Mailer: Becky! ver. 2.82.01 [en] Hi, > Hi - > > a Gentoo user recently found that 6.18.2 started to reproducuibly > crash when building their go toolchain [1]. > > Apparently the addition of "sched/fair: Forfeit vruntime on yield" > (mainline 79104becf42b) can result in the infamous NULL returned from > pick_eevdf(), which is not supposed to happen. > > It turned out that the mentioned commit triggered a bug related > to the recently added proxy execution feature, which was already > fixed in mainline by "sched/proxy: Yield the donor task" > (127b90315ca0), though not marked for stable. > > Applying this to 6.18.2/.3-rc1 (and probably 6.12 as well) > has reproducibly fixed the problem. A possible reason the crash > was triggered by the Go runtime could be its specific use of yield(), > though that's just speculation on my part. > > So please add 127b90315ca0 ("sched/proxy: Yield the donor task") > to 6.18.y/6.12.y. I know we're already in 6.18.3-rc1, but the > crasher seems reproducible. Failed to apply 127b90315ca0 ("sched/proxy: Yield the donor task") to 6.12.y, because the 'donor taskˇ® is a feature of 6.13. commit af0c8b2bf67b25756f27644936e74fd9a6273bd2 Author: Peter Zijlstra Date: Wed Oct 9 16:53:40 2024 -0700 sched: Split scheduler and execution contexts Best Regards Wang Yugui (wangyugui@e16-tech.com) 2025/12/31