From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3tf4C82YDCzDw3P for ; Thu, 15 Dec 2016 05:01:40 +1100 (AEDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id uBEHsJ20146911 for ; Wed, 14 Dec 2016 13:01:37 -0500 Received: from e24smtp05.br.ibm.com (e24smtp05.br.ibm.com [32.104.18.26]) by mx0b-001b2d01.pphosted.com with ESMTP id 27b667cf42-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 14 Dec 2016 13:01:36 -0500 Received: from localhost by e24smtp05.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 14 Dec 2016 16:01:34 -0200 Received: from d24relay04.br.ibm.com (d24relay04.br.ibm.com [9.18.232.146]) by d24dlp01.br.ibm.com (Postfix) with ESMTP id A5166352006C for ; Wed, 14 Dec 2016 13:01:00 -0500 (EST) Received: from d24av02.br.ibm.com (d24av02.br.ibm.com [9.8.31.93]) by d24relay04.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id uBEI1UBL55378066 for ; Wed, 14 Dec 2016 16:01:30 -0200 Received: from d24av02.br.ibm.com (localhost [127.0.0.1]) by d24av02.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id uBEI1Uxw013089 for ; Wed, 14 Dec 2016 16:01:30 -0200 From: "Guilherme G. Piccoli" To: tglx@linutronix.de, linux-kernel@vger.kernel.org Cc: gabriel@krisman.be, hch@lst.de, linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, gpiccoli@linux.vnet.ibm.com, stable@vger.kernel.org.#.v4.9+ Subject: [PATCH] genirq/affinity: fix node generation from cpumask Date: Wed, 14 Dec 2016 16:01:12 -0200 Message-Id: <1481738472-2671-1-git-send-email-gpiccoli@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Cc: stable@vger.kernel.org # v4.9+ Cc: Christoph Hellwig Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-pci@vger.kernel.org --- kernel/irq/affinity.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c index 9be9bda..464eaf0 100644 --- a/kernel/irq/affinity.c +++ b/kernel/irq/affinity.c @@ -37,15 +37,15 @@ 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++; } - } + return 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) { -- 2.1.0