On Fri, Aug 22, 2025 at 03:33:02AM +0000, Jinjie Ruan wrote:
> There is a vector setup race, which overwrites the interrupt
> descriptor in the per CPU vector array resulting in a disfunctional device.
>
> CPU0 CPU1
> interrupt is raised in APIC IRR
> but not handled
> free_irq()
> per_cpu(vector_irq, CPU1)[vector] = VECTOR_SHUTDOWN;
>
> request_irq() common_interrupt()
> d = this_cpu_read(vector_irq[vector]);
>
> per_cpu(vector_irq, CPU1)[vector] = desc;
>
> if (d == VECTOR_SHUTDOWN)
> this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
>
> free_irq() cannot observe the pending vector in the CPU1 APIC as there is
> no way to query the remote CPUs APIC IRR.
>
> This requires that request_irq() uses the same vector/CPU as the one which
> was freed, but this also can be triggered by a spurious interrupt.
>
> Interestingly enough this problem managed to be hidden for more than a
> decade.
>
> Prevent this by reevaluating vector_irq under the vector lock, which is
> held by the interrupt activation code when vector_irq is updated.
>
> The first patch provides context for subsequent real bugfix patch.
>
> Fixes: 9345005f4eed ("x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs")
> Cc: stable@vger.kernel.org#5.10.x
> Cc: gregkh@linuxfoundation.org
>
> v1 -> RESEND
> - Add upstream commit ID.
>
> Jacob Pan (1):
> x86/irq: Factor out handler invocation from common_interrupt()
>
> Thomas Gleixner (1):
> x86/irq: Plug vector setup race
>
> arch/x86/kernel/irq.c | 70 ++++++++++++++++++++++++++++++++++---------
> 1 file changed, 56 insertions(+), 14 deletions(-)
>
> --
> 2.34.1
>
>
Dropping as I didn't take the patches for later kernels either.
greg k-h