From nobody Thu Nov 28 04:48:52 2024 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 49CF221F420 for ; Fri, 4 Oct 2024 18:06:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728065209; cv=none; b=GSmgGQAr2RR4MJeD/LSUU2RasoB8NqkePKHCjkbe+15nWuU2YuVEBVgyTVwISXYtFOfJE5GGLgc5PVOqzCRucdhsz5aX37Qa4m0OJnJPdoHygH1Ah93MAZqEkP0t9wScSMHromHdhjLua2wHuDs0FJ//E8zuNJCVGF+9YaRVlfI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728065209; c=relaxed/simple; bh=EXrJZrDpJo5yTmt2JeTyeW1rUnPhmMxIBkHhQPq8l+c=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=SfjcJ4cj5Bd0rJEMrcjhYsaM8WA6w3wPjebamK2Ez9ad0md6lrL+fXLacrfwBhYcAdw7q+gC/edcpOw0YEMs4ajdFe9n1MfoKduYXqd5U5hsfx7p0UhnVF4AeRXXAVhTbmTgzhfsq1xxoY4Yq6gvKvE8I9u1F1GWnbBASeG+72Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 711861063; Fri, 4 Oct 2024 11:07:17 -0700 (PDT) Received: from merodach.members.linode.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C34603F58B; Fri, 4 Oct 2024 11:06:44 -0700 (PDT) From: James Morse To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , James Morse , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Rex Nie , Dave Martin , Shaopeng Tan Subject: [PATCH v5 32/40] x86/resctrl: resctrl_exit() teardown resctrl but leave the mount point Date: Fri, 4 Oct 2024 18:03:39 +0000 Message-Id: <20241004180347.19985-33-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20241004180347.19985-1-james.morse@arm.com> References: <20241004180347.19985-1-james.morse@arm.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 Content-Type: text/plain; charset="utf-8" resctrl_exit() was intended for use when the 'resctrl' module was unloaded. resctrl can't be built as a module, and the kernfs helpers are not exported so this is unlikely to change. MPAM has an error interrupt which indicates the MPAM driver has gone haywire. Should this occur tasks could run with the wrong control values, leading to bad performance for important tasks. The MPAM driver needs a way to tell resctrl that no further configuration should be attempted. Using resctrl_exit() for this leaves the system in a funny state as resctrl is still mounted, but cannot be un-mounted because the sysfs directory that is typically used has been removed. Dave Martin suggests this may cause systemd trouble in the future as not all filesystems can be unmounted. Add calls to remove all the files and directories in resctrl, and remove the sysfs_remove_mount_point() call that leaves the system in a funny state. When triggered, this causes all the resctrl files to disappear. resctrl can be unmounted, but not mounted again. Signed-off-by: James Morse Tested-by: Carl Worth # arm64 Tested-by: Shaopeng Tan Reviewed-by: Shaopeng Tan --- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/r= esctrl/rdtgroup.c index f77fab859c35..bb5aadaf99b6 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -4319,9 +4319,9 @@ int __init resctrl_init(void) =20 void __exit resctrl_exit(void) { + rdtgroup_destroy_root(); debugfs_remove_recursive(debugfs_resctrl); unregister_filesystem(&rdt_fs_type); - sysfs_remove_mount_point(fs_kobj, "resctrl"); =20 resctrl_mon_resource_exit(); } --=20 2.39.2