I guess this way still can't fix the request allocation crash issue triggered by using blk_mq_alloc_request_hctx(), in which one hw queue may not be mapped from any online CPU.
Not really. I guess we will need to simply skip queues that are mapped to an offline cpu.
Maybe this patch isn't for this issue, but it is closely related.
Yes, another patch is still needed. Steve, do you still have that patch? I don't seem to find it anywhere.