From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 629FD1A9C0B for ; Fri, 2 Aug 2024 17:31:43 +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=1722619904; cv=none; b=Y0jJm91AobBp4vsscY+/Xdf1gMij10f0+iM8UQkkEWw7Iwg/m+TLaT1bfN6WtW7lCFWGXAvfdOa9Tc3v7K6C8BLK7kitt4AphNW0zN3MVjI4D5KCpiAvKOOTejZ94zR29GrDxul4S2xgVqP6I0Q/9/pbuDFtMSoGfaoSHPCqL34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722619904; c=relaxed/simple; bh=6c58T8m4eSIeZW5BpcOcXXXN3OGV4VLMYLm95bgTGw4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Br+21cLJsdE/gLY1m/qEJKRpGgw8oncJh02AB3J1d/PnZ3U+OPEG892+qyLylwNAxpVVaUFGwpnOfxe0hhzMWw+h8XU3BLHpJkt75aybA3wHimi5krYagzwe8ADGT63LCyx4jFBIJK6QJNCosH6l1Rum/Kqx7VjamVxjuOeOCqQ= 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 B009D1042; Fri, 2 Aug 2024 10:32:08 -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 11EA93F64C; Fri, 2 Aug 2024 10:31:39 -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 Subject: [PATCH v4 31/39] x86/resctrl: resctrl_exit() teardown resctrl but leave the mount point Date: Fri, 2 Aug 2024 17:28:45 +0000 Message-Id: <20240802172853.22529-32-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240802172853.22529-1-james.morse@arm.com> References: <20240802172853.22529-1-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: 8bit 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 --- 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/resctrl/rdtgroup.c index 8610a7e01f52..19f852bbc8b0 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -4327,9 +4327,9 @@ int __init resctrl_init(void) 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"); resctrl_mon_resource_exit(); } -- 2.39.2