After calling irq_set_affinity_and_hint(), the cpumask pointer is saved in desc->affinity_hint, and will be used later when reading /proc/irq/<num>/affinity_hint. So the cpumask variable needs to be persistent. Otherwise, we are accessing freed memory when reading the affinity_hint file. Also, need to clear affinity_hint before free_irq(), otherwise there is a one-time warning and stack trace during module unloading: [ 243.948687] WARNING: CPU: 10 PID: 1589 at kernel/irq/manage.c:1913 free_irq+0x318/0x360 ... [ 243.948753] Call Trace: [ 243.948754] <TASK> [ 243.948760] mana_gd_remove_irqs+0x78/0xc0 [mana] [ 243.948767] mana_gd_remove+0x3e/0x80 [mana] [ 243.948773] pci_device_remove+0x3d/0xb0 [ 243.948778] device_remove+0x46/0x70 [ 243.948782] device_release_driver_internal+0x1fe/0x280 [ 243.948785] driver_detach+0x4e/0xa0 [ 243.948787] bus_remove_driver+0x70/0xf0 [ 243.948789] driver_unregister+0x35/0x60 [ 243.948792] pci_unregister_driver+0x44/0x90 [ 243.948794] mana_driver_exit+0x14/0x3fe [mana] [ 243.948800] __do_sys_delete_module.constprop.0+0x185/0x2f0 To fix the bug, use the persistent mask, cpumask_of(cpu#), and set affinity_hint to NULL before freeing the IRQ, as required by free_irq(). Cc: stable@vger.kernel.org Fixes: 71fa6887eeca ("net: mana: Assign interrupts to CPUs based on NUMA nodes") Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Reviewed-by: Leon Romanovsky <leonro@nvidia.com> Link: https://lore.kernel.org/r/1675718929-19565-1-git-send-email-haiyangz@microsoft.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>