From 08d835dff916bfe8f45acc7b92c7af6c4081c8a7 Mon Sep 17 00:00:00 2001
From: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>
Date: Thu, 31 Mar 2022 09:33:09 +0900
Subject: [PATCH] genirq/affinity: Consider that CPUs on nodes can be
 unbalanced
Git-commit: 08d835dff916bfe8f45acc7b92c7af6c4081c8a7
Patch-mainline: v5.18-rc3
References: git-fixes

If CPUs on a node are offline at boot time, the number of nodes is
different when building affinity masks for present cpus and when building
affinity masks for possible cpus. This causes the following problem:

In the case that the number of vectors is less than the number of nodes
there are cases where bits of masks for present cpus are overwritten when
building masks for possible cpus.

Fix this by excluding CPUs, which are not part of the current build mask
(present/possible).

[ tglx: Massaged changelog and added comment ]

Fixes: b82592199032 ("genirq/affinity: Spread IRQs to all available NUMA nodes")
Signed-off-by: Rei Yamamoto <yamamoto.rei@jp.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220331003309.10891-1-yamamoto.rei@jp.fujitsu.com
Signed-off-by: Frederic Weisbecker <fweisbecker@suse.com>
---
 kernel/irq/affinity.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index f7ff8919dc9b..fdf170404650 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -269,8 +269,9 @@ static int __irq_build_affinity_masks(unsigned int startvec,
 	 */
 	if (numvecs <= nodes) {
 		for_each_node_mask(n, nodemsk) {
-			cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
-				   node_to_cpumask[n]);
+			/* Ensure that only CPUs which are in both masks are set */
+			cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
+			cpumask_or(&masks[curvec].mask, &masks[curvec].mask, nmsk);
 			if (++curvec == last_affv)
 				curvec = firstvec;
 		}
-- 
2.25.1