From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 89E223CF1E7; Wed, 8 Jul 2026 19:09:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783537796; cv=none; b=juUgF+uOmAWVKoOnM3E79l0NdEhIpymu8gGphV8nWNqEBE7m/s4HFqA0wipVKZxb/5ntE7XWuHsCLAF9KBjHY9m/BLtKulTT54L5lGO1LpD2OVAVrgcDQ/U6G6g2yPcEVfPozk4pC6W/ChK45haFYmrDwRA1Q4855ndud6fW3As= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783537796; c=relaxed/simple; bh=IHpWtP0FcTkhS/GIjzc91SE+h1lBGL944YPeJ/X+110=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References; b=u569WljabhmA6icPbsQ0u3WrsjWn8yWZ01FbDLNZMY14SaJ+81Qnt1uXGxV85wggHv133FXKpPe/wNEnkaJaBux9W3mGp9wq4lHkRQ+K9mGJJnLF4MwesfqLh/nw0QVuaiwC1BsIZe1jqDBKbNMZ9L1RLm0ogZgxKnBytuWzexs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JQTeXRxS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JQTeXRxS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EDAF1F00A3D; Wed, 8 Jul 2026 19:09:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783537785; bh=ginsaI+HyRIcyHqi34yOhEM5q95MZdTRNgahmXbcuLo=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=JQTeXRxSNOYdgUPY0Xx0VQvcU3DDPFRe2ZjU2GO9kMzPhxYA5HJUAtYUMlY14/Nz/ ElQ7C6a2AqDk3zkR8ssPomAACBS+23KFcIYkWBEkPITu2SDnEZp18X6PwpeC1U14wl W1cHsD9AxrvJqc6ccKc4Nw0Cwe8F8LiD1FelS++DgmwEJSYnmq/sng17kIuQKP3vSq yDNy6w9qMIU2EnarvvH1EJ4Mqn/45UcUtdJcUW3KEWyv0G9o/Ue2ITkr7JJCSAwvLA Pj1QayglTjDvyHcqEg0Pt40fPnqyUQG1UsW+CaKPqJtDx1wHJAPKUT3RrUlw+dz5CH 92vpUZSFedGVg== Date: Wed, 08 Jul 2026 09:09:44 -1000 Message-ID: From: Tejun Heo To: sashiko-bot@kernel.org Cc: David Vernet , Andrea Righi , Changwoo Min , sched-ext@lists.linux.dev, Emil Tsalapatis , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 sched_ext/for-7.3 35/36] tools/sched_ext: scx_qmap - Expand hierarchical sub-scheduling In-Reply-To: <20260707004101.869821F000E9@smtp.kernel.org> References: <20260707001229.1410929-1-tj@kernel.org> <20260707001229.1410929-36-tj@kernel.org> <20260707004101.869821F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: On Tue, 07 Jul 2026 00:41:01 +0000, sashiko-bot@kernel.org wrote: > - [Medium] Newly acquired exclusive CPUs are not added to `idle_cids.mask` if they were already idle when ownership changed, leading to lost wakeups. > - [Medium] Tasks pinned exclusively to delegated CPUs will be permanently stranded in `SHARED_DSQ`. > - [Medium] `qmap_sub_attach` and `qmap_sub_detach` modify the `sub_sched_ctxs` array without synchronization, causing data races with timer-driven partition updates. 1. Real - a cid already idle when it's reclaimed into the owned set was missed. Fixed by making idle_cids track physical idleness for every cid and masking it against the owned set at dispatch, so no reseed is needed. 2. Known limitation - a task affined only to delegated cids strands in SHARED_DSQ. This is the missing per-affinity fallback, now noted in the cover letter; a later series adds a root-reserved fallback slice. 3. Real but self-healing - the fields are re-derived by the following redistribute(). The clean fix (a bpf_spin_lock over the accesses) isn't usable because the cmask ops it would guard call kfuncs, which the verifier forbids inside a bpf_spin_lock section. Left as-is for the demo. Thanks. -- tejun