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 1BBB13B1EC8; Fri, 11 Sep 2026 16:57:29 +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=1789145860; cv=none; b=eSw9uH/zdq/2a/VXXYWEm5DomR6WcBimInnU0QU+vxdLIJrvNu9USs4L9dQAmdeu1X4XDw0faXeLaDBIc1F952lrRNURII5az9dkJZvC4SW0H1vYiMIw8Ia9V/ecsbyKk0MESO0KdMnlJerBAyefMCq7AtAoAvZacmAqdI2wZlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789145860; c=relaxed/simple; bh=Q2v3W0b61GMl7gGnUQ7c8+penetqAlw9A8ubBI1X4Hw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ngTpNlcuYdFfZm0Milc52WHBmaeTQQObyPCB6QDpHKsQyMw+j5Y1TmJHSNsSWdnELxf9SBglf9evap/ajn8Bf732H93lVKzUSOKT5Tv8qAl8fVRrkRAVz0e1N8lfgWXSTLEoiFCaHwNwHNyQKc1XDW8CI0wj0Ch1pOsNhP+z3uQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Deku9Ls4; 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="Deku9Ls4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 780631F00893; Fri, 11 Sep 2026 16:57:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789145846; bh=tksrUNGbHdaSFb+5rLGabIokdhFX+wv8b1iFL7wLAA0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Deku9Ls4TkXJj86McT9Ziakd7EkSopLwLX6bNCEoJSyvmPdm0sUUKMkRl50eQeq5U +SWSzmSwGsxUVkjv7rolW5xYQcA8ETGAuCY465B6n2XW15Nm7hlrQ/N4wrhz8rbIgZ ymTUWkp+7/rCd4SbL6vMAK0kbKpbektQFzgm+pANAOCAN+tfI23dbFMF4Jc4VBp8Sq MRsVSfRyPbLHBg3r7u7acB32HtwgYDxJlliaypdqfLgBHTPJmNFGaEC4L1rI3gs1ii JPahsopeOALJ/4xoIpCgg1xHZ4EEnw8AAt1HUdylBWvZp0Zby8E9nVsFsK/kReFH5P FD7Fy1wGtfLHw== Date: Fri, 11 Sep 2026 06:57:25 -1000 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: Noah Feldt , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, N.Feldt@mittwald.de, carnil@debian.org, dschatzberg@meta.com, hannes@cmpxchg.org, peterz@infradead.org, stable@vger.kernel.org Subject: Re: [PATCH v2] cgroup: Avoid iteration of dying tasks with zero refcount Message-ID: References: <20260907192723.72167-1-noah@feldt.systems> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Fri, Sep 11, 2026 at 06:11:42PM +0200, Michal Koutný wrote: > On Tue, Sep 08, 2026 at 05:55:45PM +0200, Michal Koutný wrote: > > Though, the fix loses a bit of elegance. Hm, thinking... > > So, it occurs to me that the ->live based predicate from v2 might break > CSS_TASK_ITER_WITH_DEAD callers (zombies they asked for would be > skipped). > We need to distinguish between (both on dying_tasks list): > - regular zombies waiting to be reaped and > - RCU remnant tasks that are going to be free'd. > IIUC these two are split on the ->usage count. (Correct me if I'm > wrong.) > > I'm starting to like the tryget_task_struct() approach from v1 again. Yeah, let's go back to v1. Sorry about the noise. Thanks. -- tejun