Re: [BUG] nvme driver crash

[Shaohua Li <shli@kernel.org>]

On Wed, Jul 26, 2017 at 12:12:21PM -0700, Omar Sandoval wrote:
> On Wed, Jul 26, 2017 at 10:34:43AM -0700, Christoph Hellwig wrote:
> > On Tue, Jul 25, 2017 at 03:24:08PM -0700, Shaohua Li wrote:
> > > Disable CONIFG_SMP, kernel crashes at boot time, here is the log.
> > 
> > I can reproduce the issue.  Unfortunately the addresss in the bug
> > doesn't make any sense to me when resolving it using gdb, as t just
> > points to the line where blk_mq_init_queue calls
> > blk_alloc_queue_node.
> > 
> > Can you check if you get better results in your build?
> 
> It's crashing on that line because ctrl->tagset is NULL, which is
> because...
> 
> irq_create_affinity_masks() returns NULL on !CONFIG_SMP
> -> pci_irq_get_affinity() returns NULL
> -> blk_mq_pci_map_queues() returns -EINVAL
> -> blk_mq_alloc_tag_set() returns -EINVAL
> -> nvme_dev_add() doesn't set ctrl->tagset
> 
> The two-fold fix would be to make the nvme driver handle
> blk_mq_alloc_tag_set() failing and to fall back to a dumb mapping in
> blk_mq_pci_map_queues(), but I don't know what the best way to do those
> is.

irq_create_affinity_masks returns null and prints error, could we fix that?