On Sun, Dec 16 2018 at 11:16am -0500,
Christoph Hellwig <[email protected]> wrote:

> On Sun, Dec 16, 2018 at 10:25:16AM +0800, Ming Lei wrote:
> > This patch sets map->nr_queues as zero explictly if there is zero
> > queues for such queue type, then blk_mq_map_swqueue() can become
> > more robust to deal with shared mappings.
> 
> This looks a lot more clumsy than what we had before, can you explain
> what additional robustnes it buys us?

It enables nvme IO to complete on my testbed with for-4.21/block
changes, this NUMA layout is what triggered Ming's work:

# numactl --hardware
available: 2 nodes (0-1)
node 0 cpus: 0 2 4 6 8 10 12 14
node 0 size: 128605 MB
node 0 free: 128092 MB
node 1 cpus: 1 3 5 7 9 11 13 15
node 1 size: 128997 MB
node 1 free: 128529 MB
node distances:
node   0   1
  0:  10  21
  1:  21  10

Without the aggregate changes from this patchset (1-3 anyway) I get IO
hangs in blkdev_fsync().

With that in mind, Jens needs these fixes (or something comparable)
ASAP.

Tested-by: Mike Snitzer <[email protected]>

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