The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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

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

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; }