From: Joerg Roedel <jroedel@xxxxxxx> [ Upstream commit d97eb8966c91f2c9d05f0a22eb89ed5b76d966d1 ] When an interrupt is migrated away from a cpu it will stay in its vector_irq array until smp_irq_move_cleanup_interrupt succeeded. The cfg->move_in_progress flag is cleared already when the IPI was sent. When the interrupt is destroyed after migration its 'struct irq_desc' is freed and the vector_irq arrays are cleaned up. But since cfg->move_in_progress is already 0 the references at cpus before the last migration will not be cleared. So this would leave a reference to an already destroyed irq alive. When the cpu is taken down at this point, the check_irq_vectors_for_cpu_disable() function finds a valid irq number in the vector_irq array, but gets NULL for its descriptor and dereferences it, causing a kernel panic. This has been observed on real systems at shutdown. Add a check to check_irq_vectors_for_cpu_disable() for a valid 'struct irq_desc' to prevent this issue. Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Reviewed-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Jan Beulich <JBeulich@xxxxxxxx> Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Prarit Bhargava <prarit@xxxxxxxxxx> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Yinghai Lu <yinghai@xxxxxxxxxx> Cc: alnovak@xxxxxxxx Cc: joro@xxxxxxxxxx Link: http://lkml.kernel.org/r/20150204132754.GA10078@xxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/x86/kernel/irq.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 37907756fc41..1d6e2946a3da 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -302,6 +302,9 @@ int check_irq_vectors_for_cpu_disable(void) irq = __this_cpu_read(vector_irq[vector]); if (irq >= 0) { desc = irq_to_desc(irq); + if (!desc) + continue; + data = irq_desc_get_irq_data(desc); cpumask_copy(&affinity_new, data->affinity); cpu_clear(this_cpu, affinity_new); -- 2.17.1
