linux-kernel - [PATCH v2] irq: consider cpus on nodes are unbalanced

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Message-Id: <20211217104407.2156-1-yamamoto.rei@jp.fujitsu.com>
Date:   Fri, 17 Dec 2021 19:44:07 +0900
From:   Rei Yamamoto <yamamoto.rei@...fujitsu.com>
To:     tglx@...utronix.de
Cc:     hch@....de, kbusch@...nel.org, linux-kernel@...r.kernel.org,
        maz@...nel.org, ming.lei@...hat.com, yamamoto.rei@...fujitsu.com
Subject: [PATCH v2] irq: consider cpus on nodes are unbalanced

If cpus on a node are offline at boot time, there are
difference in the number of nodes between when building affinity
masks for present cpus and when building affinity masks for possible
cpus. This patch fixes a problem caused by the difference of the
number of nodes:

 - The routine of "numvecs <= nodes" condition can overwrite bits of
   masks for present cpus in building masks for possible cpus. Fix this
   problem by making CPU bits, which is not target, not changing.

Signed-off-by: Rei Yamamoto <yamamoto.rei@...fujitsu.com>
---
 kernel/irq/affinity.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index f7ff8919dc9b..d2d01565d2ec 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_and(nmsk, cpu_mask, node_to_cpumask[n]);
 			cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
-				   node_to_cpumask[n]);
+				   nmsk);
 			if (++curvec == last_affv)
 				curvec = firstvec;
 		}
-- 
2.27.0