On Mon, 15 Feb 2021 10:45:06 +0100, Greg Kurz wrote:
> Depending on the number of online CPUs in the original kernel, it is
> likely for CPU #0 to be offline in a kdump kernel. The associated IRQs
> in the affinity mappings provided by irq_create_affinity_masks() are
> thus not started by irq_startup(), as per-design with managed IRQs.
>
> This can be a problem with multi-queue block devices driven by blk-mq :
> such a non-started IRQ is very likely paired with the single queue
> enforced by blk-mq during kdump (see blk_mq_alloc_tag_set()). This
> causes the device to remain silent and likely hangs the guest at
> some point.
>
> [...]
Applied to powerpc/fixes.
[1/1] powerpc/pseries: Don't enforce MSI affinity with kdump
https://git.kernel.org/powerpc/c/f9619d5e5174867536b7e558683bc4408eab833f
cheers
