Chris reported that the recent affinity management changes result in
overwriting the already initialized thread flags.

Use set_bit() to set the affinity bit instead of assigning the bit value to
the flags.

Fixes: 801afdfbfcd9 ("genirq: Fix interrupt threads affinity vs. cpuset isolated partitions")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Closes: https://lore.kernel.org/all/20251212014848.3509622-1-clm@meta.com
---
 kernel/irq/manage.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1414,7 +1414,7 @@ setup_irq_thread(struct irqaction *new,
 	 * Ensure the thread adjusts the affinity once it reaches the
 	 * thread function.
 	 */
-	new->thread_flags = BIT(IRQTF_AFFINITY);
+	set_bit(IRQTF_AFFINITY, &new->thread_flags);
 
 	return 0;
 }

Le Fri, Dec 12, 2025 at 01:01:04PM +0900, Thomas Gleixner a écrit :
> Chris reported that the recent affinity management changes result in
> overwriting the already initialized thread flags.
> 
> Use set_bit() to set the affinity bit instead of assigning the bit value to
> the flags.
> 
> Fixes: 801afdfbfcd9 ("genirq: Fix interrupt threads affinity vs. cpuset isolated partitions")
> Reported-by: Chris Mason <clm@meta.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Closes: https://lore.kernel.org/all/20251212014848.3509622-1-clm@meta.com

Whoops!

Acked-by: Frederic Weisbecker <frederic@kernel.org>

-- 
Frederic Weisbecker
SUSE Labs

The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     fbbd7ce627af733ded7971b2495b0d099a0a80da
Gitweb:        https://git.kernel.org/tip/fbbd7ce627af733ded7971b2495b0d099a0a80da
Author:        Thomas Gleixner <tglx@linutronix.de>
AuthorDate:    Fri, 12 Dec 2025 13:01:04 +09:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 13 Dec 2025 10:29:33 +09:00

genirq: Don't overwrite interrupt thread flags on setup

Chris reported that the recent affinity management changes result in
overwriting the already initialized thread flags.

Use set_bit() to set the affinity bit instead of assigning the bit value to
the flags.

Fixes: 801afdfbfcd9 ("genirq: Fix interrupt threads affinity vs. cpuset isolated partitions")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://patch.msgid.link/87ecp0e4cf.ffs@tglx
Closes: https://lore.kernel.org/all/20251212014848.3509622-1-clm@meta.com
---
 kernel/irq/manage.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 8b1b4c8..349ae79 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1414,7 +1414,7 @@ setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
 	 * Ensure the thread adjusts the affinity once it reaches the
 	 * thread function.
 	 */
-	new->thread_flags = BIT(IRQTF_AFFINITY);
+	set_bit(IRQTF_AFFINITY, &new->thread_flags);
 
 	return 0;
 }