From: Joerg Roedel jroedel@suse.de
[ 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@suse.de Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Jiang Liu jiang.liu@linux.intel.com Cc: H. Peter Anvin hpa@zytor.com Cc: Jan Beulich JBeulich@suse.com Cc: K. Y. Srinivasan kys@microsoft.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Prarit Bhargava prarit@redhat.com Cc: Rasmus Villemoes linux@rasmusvillemoes.dk Cc: Yinghai Lu yinghai@kernel.org Cc: alnovak@suse.com Cc: joro@8bytes.org Link: http://lkml.kernel.org/r/20150204132754.GA10078@suse.de Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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);