From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B48B7366577; Tue, 3 Mar 2026 17:59:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772560742; cv=none; b=kA8Vrptj+3ZDf8AHy/XSZxNK0DrUHdpJKDzKfrdXd+BeO412SXRb3la+vbYmb//I+lGSEAHuDTsyj66J1g6+s3P31M+MKoSfEBTBnJgdM7PRtOSQMqnco/BJTDtTxsGteqHd0kW85bndny6tnCj88iJAMyRNNSW8mNdefxuQCmA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772560742; c=relaxed/simple; bh=bPr1d4FsEvE8qaKE4jC8j8uofFzZp53mFL2kXJfOrvw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=am85IhWYsomXmDTxzNlgeU27TXwDKn8SDVRgT6d9iG+ZkU8WrPLSs2hiWUxoYbMy3p/1+CM+drxmm2XN+PdNoXzdD3lTJUmvH2oGOpkksauYZhxY5UHfON7n6FU6gXUbxXJM1jVZP48/SlsGLCthIoygEzBYf3ONeWxqitemdXQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HejWsx0k; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HejWsx0k" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 28383C116C6; Tue, 3 Mar 2026 17:59:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772560742; bh=bPr1d4FsEvE8qaKE4jC8j8uofFzZp53mFL2kXJfOrvw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HejWsx0keLtia0uk0VFk+qjpnZJoxLP+LGfAiDcxrThwkOqPbNVBcsi9AJO5UEvuN s9gM2Zs+Cww1tTH8LVutuZwC7FEOXZiLqhhLegk8By73U/jCivGYKCz+/F7ZXZYqef q5a96EBXVurR2ZS7CzM5af4DglGYUf2eAdPR9wKzs/71J1G4YlUOcA37l/x1BGsg1N 5Y59lNjUrBy3mzsnwACo9ISPqEvnl6q4btKvor1+C0cYiKJGR5iMrcsBwl7w4djkNI P/Ye1FLsS2jtwZXTiJKWkzYV957G6+cADKhdecwZoHwDcgrMQ+r9Q5usbuqMAugCra 21MtddHddkOjQ== Date: Tue, 3 Mar 2026 07:59:01 -1000 From: Tejun Heo To: Sebastian Andrzej Siewior Cc: linux-rt-devel@lists.linux.dev, cgroups@vger.kernel.org, Johannes Weiner , Michal =?iso-8859-1?Q?Koutn=FD?= , Clark Williams , Steven Rostedt , Bert Karwatzki Subject: Re: [PATCH] cgroup: Don't expose dead tasks in cgroup Message-ID: References: <20260302120738.6KkDipsR@linutronix.de> <20260303131301.ieSSCM4n@linutronix.de> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260303131301.ieSSCM4n@linutronix.de> Hello, On Tue, Mar 03, 2026 at 02:13:01PM +0100, Sebastian Andrzej Siewior wrote: ... > I get the same timeout behaviour on !PREEMPT_RT. So it seems like I did > reduce the race window. I see. > So what about doing the removal before sending the signal about the > upcoming death? Something like: d245698d727a ("cgroup: Defer task cgroup unlink until after the task is done switching out") is what created the big wide window causing the regression and we need that because otherwise the cgroup controllers get confused. I think we need to figure out where we need to start hiding tasks from listing to remove the race window and do that explicitly. Thanks. -- tejun