From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 A207B3A75AD for ; Mon, 20 Apr 2026 17:44:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776707088; cv=none; b=dr8w0P0O9p3bbF8pgtMhlBcvURAJbLX9Tu70zDlk20zI8zNTBzMLb8aHu24lVXyswMK/6Abtj0+MuUkfKRAXKlEIXYhy6YokEu4Rneb8X+kyJInmJf6V5n23wRbXAto9/dAtwH/GNTeRXlb54NbJyqIiOKgZnGeC9T7VLCL8gRA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776707088; c=relaxed/simple; bh=R72b3K6jz1tHjZxm7IaNA1g7loVMQoHiUU5Fx23xmuY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aK5m3+AXTrJHw7nOP9tpi88XKrlMim6IZOR0S1AkJUZoA1HgdxWzPj+oE3DIfle1EqvKZLKKxe9XKXxuDDWGApdwL94ZPTntt1PLIgykBe452Cju+DUulOSqhASdg/tO7UcfjufL1ibLm9nlum6fOqpV6TB+01A8UH+of6HQVF0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=PwDuPEd4; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="PwDuPEd4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1776707086; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=H/9htZ55gqnG10ouhQdXUGui1FWiGObZFJTqztwfmQI=; b=PwDuPEd4PeJDdjUK7vMWlb08zVLP/gDaBqsR0Zu6AQYfE7fCsMZjAJQdjE1U4f/LRFL1XK F/S+9IrKuUbtHIyqQdxFxnsfQ2M11u4axz4GtkzAtNHVFrq7yJWV1SCWLR9yeU1v4PNNKs Z7mpBpjy29fzYODUUgxR/sewBFpAr3c= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-474-1Tv9FQ6aNVai2nCvUyZdwQ-1; Mon, 20 Apr 2026 13:44:43 -0400 X-MC-Unique: 1Tv9FQ6aNVai2nCvUyZdwQ-1 X-Mimecast-MFC-AGG-ID: 1Tv9FQ6aNVai2nCvUyZdwQ_1776707082 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D572F195608E; Mon, 20 Apr 2026 17:44:41 +0000 (UTC) Received: from [10.22.65.81] (unknown [10.22.65.81]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 225A3180047F; Mon, 20 Apr 2026 17:44:39 +0000 (UTC) Message-ID: Date: Mon, 20 Apr 2026 13:44:39 -0400 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] cgroup/cpuset: Skip security check for hotplug induced v1 task migration To: =?UTF-8?Q?Michal_Koutn=C3=BD?= Cc: Chen Ridong , Tejun Heo , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260331151108.2771560-1-longman@redhat.com> <20260331151108.2771560-3-longman@redhat.com> <7i2hhyijet57lfwvz3ipzlwrze3i6bm343evgpjixmj6bj44kl@rhszdi6rlycg> Content-Language: en-US From: Waiman Long In-Reply-To: <7i2hhyijet57lfwvz3ipzlwrze3i6bm343evgpjixmj6bj44kl@rhszdi6rlycg> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 On 4/20/26 1:08 PM, Michal Koutný wrote: > On Tue, Mar 31, 2026 at 11:11:08AM -0400, Waiman Long wrote: >> If a strict security policy is in place, however, the task migration >> may fail when security_task_setscheduler() call in cpuset_can_attach() >> returns a -EACCESS error. > I think this should be generally safe to skip (since v2 doesn't consider > the object of cpuset migration at all). > >> That will mean that those tasks will have no CPU to run on. The system >> administrators will have to explicitly intervene to either add CPUs to >> that cpuset or move the tasks elsewhere if they are aware of it. > That "no CPU to run on" means the affected tasks would remain in > schedule() indefinitely? I believe the scheduler has a fallback mechanism in that particular case, but it can be any CPU. So I don't think we should rely on that. Cheers, Longman