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 9D3E2188006; Mon, 23 Dec 2024 16:10:55 +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=1734970255; cv=none; b=l1Xf/YZcbx5jMW5KCYqHu/94Oih7HLFgl+udTtvcM3DBIos72RvRj67+zvaih31WIe8m+7GQU+iGRgpx4qk++rU6H0PVdzPdMS+qRXGERFb5pb2W/O3P9EFPe9fqGc4qQQb6rjuMK2cDJ1Ag4AEqZWq3P7Ho/4CEE79/WkqBV84= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734970255; c=relaxed/simple; bh=Q04f/SqFyX9uDr1A7kf7+73jdSFyASTNF7CRc06l6GM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=uQhjPdfT62XMByHAXWV7YNH2HfQbJynubVc9R5j+ocKlFviTOfZG7M9U4Jn4O7jDdDx9NEnF/fr2huPybbuOqsYRpsvaIxpq8IepsLfk5GNw3sS5B6wlK/HG/+Q21xyD7uIR+0lj9PITh7p4pvBzQljVFouxJ2WDpd5W+Pk79Sg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pL+rYY0u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="pL+rYY0u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C58CC4CED3; Mon, 23 Dec 2024 16:10:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734970255; bh=Q04f/SqFyX9uDr1A7kf7+73jdSFyASTNF7CRc06l6GM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pL+rYY0uHPq9TiNJf1BZsk979wEfPMMs257lbWJp05UIKQc6MRi394g8I4m2MdYDo f8AGj+xs7zO+M/iTextzAUaBq8VTRQJqZV3Ftwyc6qMkHZJ518dKjTUcZOs/GHP1HK Rsk74U8nK26h7yOVlEp9qzhtbl6ec1u/brg1EAyg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Adrian Huang , Jiwei Sun , =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= , Bjorn Helgaas , Nirmal Patel , Sasha Levin Subject: [PATCH 6.6 003/116] PCI: vmd: Create domain symlink before pci_bus_add_devices() Date: Mon, 23 Dec 2024 16:57:53 +0100 Message-ID: <20241223155359.679170563@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241223155359.534468176@linuxfoundation.org> References: <20241223155359.534468176@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiwei Sun [ Upstream commit f24c9bfcd423e2b2bb0d198456412f614ec2030a ] The vmd driver creates a "domain" symlink in sysfs for each VMD bridge. Previously this symlink was created after pci_bus_add_devices() added devices below the VMD bridge and emitted udev events to announce them to userspace. This led to a race between userspace consumers of the udev events and the kernel creation of the symlink. One such consumer is mdadm, which assembles block devices into a RAID array, and for devices below a VMD bridge, mdadm depends on the "domain" symlink. If mdadm loses the race, it may be unable to assemble a RAID array, which may cause a boot failure or other issues, with complaints like this: (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: Unable to get real path for '/sys/bus/pci/drivers/vmd/0000:c7:00.5/domain/device'' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: /dev/nvme1n1 is not attached to Intel(R) RAID controller.' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: No OROM/EFI properties for /dev/nvme1n1' (udev-worker)[2149]: nvme1n1: '/sbin/mdadm -I /dev/nvme1n1'(err) 'mdadm: no RAID superblock on /dev/nvme1n1.' (udev-worker)[2149]: nvme1n1: Process '/sbin/mdadm -I /dev/nvme1n1' failed with exit code 1. This symptom prevents the OS from booting successfully. After a NVMe disk is probed/added by the nvme driver, udevd invokes mdadm to detect if there is a mdraid associated with this NVMe disk, and mdadm determines if a NVMe device is connected to a particular VMD domain by checking the "domain" symlink. For example: Thread A Thread B Thread mdadm vmd_enable_domain pci_bus_add_devices __driver_probe_device ... work_on_cpu schedule_work_on : wakeup Thread B nvme_probe : wakeup scan_work to scan nvme disk and add nvme disk then wakeup udevd : udevd executes mdadm command flush_work main : wait for nvme_probe done ... __driver_probe_device find_driver_devices : probe next nvme device : 1) Detect domain symlink ... 2) Find domain symlink ... from vmd sysfs ... 3) Domain symlink not ... created yet; failed sysfs_create_link : create domain symlink Create the VMD "domain" symlink before invoking pci_bus_add_devices() to avoid this race. Suggested-by: Adrian Huang Link: https://lore.kernel.org/linux-pci/20240605124844.24293-1-sjiwei@163.com Signed-off-by: Jiwei Sun Signed-off-by: Krzysztof Wilczyński [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas Reviewed-by: Nirmal Patel Signed-off-by: Sasha Levin --- drivers/pci/controller/vmd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index 992fea22fd9f..5ff2066aa516 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -930,6 +930,9 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) dev_set_msi_domain(&vmd->bus->dev, dev_get_msi_domain(&vmd->dev->dev)); + WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj, + "domain"), "Can't create symlink to domain\n"); + vmd_acpi_begin(); pci_scan_child_bus(vmd->bus); @@ -969,9 +972,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features) pci_bus_add_devices(vmd->bus); vmd_acpi_end(); - - WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj, - "domain"), "Can't create symlink to domain\n"); return 0; } @@ -1047,8 +1047,8 @@ static void vmd_remove(struct pci_dev *dev) { struct vmd_dev *vmd = pci_get_drvdata(dev); - sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); pci_stop_root_bus(vmd->bus); + sysfs_remove_link(&vmd->dev->dev.kobj, "domain"); pci_remove_root_bus(vmd->bus); vmd_cleanup_srcu(vmd); vmd_detach_resources(vmd); -- 2.39.5