BUG: NULL pointer at IP: blk_mq_map_swqueue+0xbc/0x200 on 4.15.0-rc2

Tue Dec 12 00:35:02 PST 2017

On Mon, Dec 11, 2017 at 11:58:45AM +0800, Ming Lei wrote:
> As we talked offline, this IP points to cpumask_set_cpu(), seems this
> case may happen when one CPU isn't mapped to any hw queue, could you test
> the following patch to see if it helps your issue?

This looks odd as mq_map should be pre-zeroed.  If it isn't we have
a few more problems..