Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935636AbcLOLhf (ORCPT ); Thu, 15 Dec 2016 06:37:35 -0500 Received: from terminus.zytor.com ([198.137.202.10]:41666 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935374AbcLOLhc (ORCPT ); Thu, 15 Dec 2016 06:37:32 -0500 Date: Thu, 15 Dec 2016 03:37:13 -0800 From: "tip-bot for Guilherme G. Piccoli" Message-ID: Cc: gpiccoli@linux.vnet.ibm.com, hch@lst.de, gabriel@krisman.be, hpa@zytor.com, linux-kernel@vger.kernel.org, gwshan@linux.vnet.ibm.com, tglx@linutronix.de, mingo@kernel.org Reply-To: gabriel@krisman.be, hch@lst.de, gpiccoli@linux.vnet.ibm.com, mingo@kernel.org, linux-kernel@vger.kernel.org, gwshan@linux.vnet.ibm.com, tglx@linutronix.de, hpa@zytor.com In-Reply-To: <1481738472-2671-1-git-send-email-gpiccoli@linux.vnet.ibm.com> References: <1481738472-2671-1-git-send-email-gpiccoli@linux.vnet.ibm.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:irq/urgent] genirq/affinity: Fix node generation from cpumask Git-Commit-ID: c0af52437254fda8b0cdbaae5a9b6d9327f1fcd5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2967 Lines: 69 Commit-ID: c0af52437254fda8b0cdbaae5a9b6d9327f1fcd5 Gitweb: http://git.kernel.org/tip/c0af52437254fda8b0cdbaae5a9b6d9327f1fcd5 Author: Guilherme G. Piccoli AuthorDate: Wed, 14 Dec 2016 16:01:12 -0200 Committer: Thomas Gleixner CommitDate: Thu, 15 Dec 2016 12:32:35 +0100 genirq/affinity: Fix node generation from cpumask Commit 34c3d9819fda ("genirq/affinity: Provide smarter irq spreading infrastructure") introduced a better IRQ spreading mechanism, taking account of the available NUMA nodes in the machine. Problem is that the algorithm of retrieving the nodemask iterates "linearly" based on the number of online nodes - some architectures present non-linear node distribution among the nodemask, like PowerPC. If this is the case, the algorithm lead to a wrong node count number and therefore to a bad/incomplete IRQ affinity distribution. For example, this problem were found in a machine with 128 CPUs and two nodes, namely nodes 0 and 8 (instead of 0 and 1, if it was linearly distributed). This led to a wrong affinity distribution which then led to a bad mq allocation for nvme driver. Finally, we take the opportunity to fix a comment regarding the affinity distribution when we have _more_ nodes than vectors. Fixes: 34c3d9819fda ("genirq/affinity: Provide smarter irq spreading infrastructure") Reported-by: Gabriel Krisman Bertazi Signed-off-by: Guilherme G. Piccoli Reviewed-by: Christoph Hellwig Reviewed-by: Gabriel Krisman Bertazi Reviewed-by: Gavin Shan Cc: linux-pci@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: hch@lst.de Link: http://lkml.kernel.org/r/1481738472-2671-1-git-send-email-gpiccoli@linux.vnet.ibm.com Signed-off-by: Thomas Gleixner --- kernel/irq/affinity.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c index 9be9bda..4544b11 100644 --- a/kernel/irq/affinity.c +++ b/kernel/irq/affinity.c @@ -37,10 +37,10 @@ static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk, static int get_nodes_in_cpumask(const struct cpumask *mask, nodemask_t *nodemsk) { - int n, nodes; + int n, nodes = 0; /* Calculate the number of nodes in the supplied affinity mask */ - for (n = 0, nodes = 0; n < num_online_nodes(); n++) { + for_each_online_node(n) { if (cpumask_intersects(mask, cpumask_of_node(n))) { node_set(n, *nodemsk); nodes++; @@ -82,7 +82,7 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd) nodes = get_nodes_in_cpumask(cpu_online_mask, &nodemsk); /* - * If the number of nodes in the mask is less than or equal the + * If the number of nodes in the mask is greater than or equal the * number of vectors we just spread the vectors across the nodes. */ if (affv <= nodes) {