From nobody Sun Oct 5 21:57:23 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 D391429ACF9 for ; Wed, 30 Jul 2025 13:12:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753881158; cv=none; b=uitXMx7zeiHZmlynEOkXV6ILta0b5PoYL5P1lPSpDH0w4nUa8c2lqTrbqd5AI8NLWlgH8EEoZl254ctaJENQb77D7XRNkODDZUKQLCtoLz6clCSzRh96qeYWK1+s32STD+dXP5D+eDnDXlZ9qVfvqKB8pDhEyZa+SnY420M9EkQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753881158; c=relaxed/simple; bh=reWgS9RUObNEsF/lZY7XBsCrlm+lIeDHni+JUOC+Zb0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XgETXI5sd7Tk9vYRwa1fbOp7ScKPnVVHbdgCOBNmOooIN3hcM137UWApjIG8BliX7XL68HMvhy9WzprR5Cyrh3K07LF6C8bH1tGe5g8XsXRloTLmdk2cHE6Fv+uEXJAZmTadmSfUTBq/Qde7rl4iK29XAjifDdNWqDTzvJZVvTs= 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=ejDqiO0l; arc=none smtp.client-ip=170.10.129.124 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="ejDqiO0l" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753881155; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=GqZBtyD7Mqgk+C8qfOHTUrfJJw6zvJ1DQPHGjsrMFf8=; b=ejDqiO0l4X3+Cn06Zm61iifRd2awyhqbO3BvRH4X1skubPlteMf0Rmm7rkuHrDU36BSHXs W3mP1UCp6fU7NU+tO846FSXQ7qwwAqJWk+UBnlbdyzJumshyajtm1Qk7G26bRTde8PkFSm QPIvYjwiQhjETnncZLLIFZe5O+1m6a0= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-599-h3K7AaBNMdKeySN3iREt-A-1; Wed, 30 Jul 2025 09:12:34 -0400 X-MC-Unique: h3K7AaBNMdKeySN3iREt-A-1 X-Mimecast-MFC-AGG-ID: h3K7AaBNMdKeySN3iREt-A_1753881152 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E6E7F18001CA; Wed, 30 Jul 2025 13:12:31 +0000 (UTC) Received: from gmonaco-thinkpadt14gen3.rmtit.com (unknown [10.44.33.26]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id ECA3419560A2; Wed, 30 Jul 2025 13:12:28 +0000 (UTC) From: Gabriele Monaco To: linux-kernel@vger.kernel.org, Anna-Maria Behnsen , Frederic Weisbecker , Thomas Gleixner , Waiman Long Cc: Gabriele Monaco Subject: [PATCH v9 6/8] sched/isolation: Force housekeeping if isolcpus and nohz_full don't leave any Date: Wed, 30 Jul 2025 15:11:56 +0200 Message-ID: <20250730131158.101668-7-gmonaco@redhat.com> In-Reply-To: <20250730131158.101668-1-gmonaco@redhat.com> References: <20250730131158.101668-1-gmonaco@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" Currently the user can set up isolcpus and nohz_full in such a way that leaves no housekeeping CPU (i.e. no CPU that is neither domain isolated nor nohz full). This can be a problem for other subsystems (e.g. the timer wheel imgration). Prevent this configuration by invalidating the last setting in case the union of isolcpus and nohz_full covers all CPUs. Reviewed-by: Frederic Weisbecker Signed-off-by: Gabriele Monaco --- kernel/sched/isolation.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 93b038d48900..0019d941de68 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -165,6 +165,18 @@ static int __init housekeeping_setup(char *str, unsign= ed long flags) } } =20 + /* Check in combination with the previously set cpumask */ + type =3D find_first_bit(&housekeeping.flags, HK_TYPE_MAX); + first_cpu =3D cpumask_first_and_and(cpu_present_mask, + housekeeping_staging, + housekeeping.cpumasks[type]); + if (first_cpu >=3D nr_cpu_ids || first_cpu >=3D setup_max_cpus) { + pr_warn("Housekeeping: must include one present CPU neither " + "in nohz_full=3D nor in isolcpus=3D, ignoring setting %s\n", + str); + goto free_housekeeping_staging; + } + iter_flags =3D flags & ~housekeeping.flags; =20 for_each_set_bit(type, &iter_flags, HK_TYPE_MAX) --=20 2.50.1