[PATCH 4.15-rc 1/3] nvme-core: Don't set nvme_wq as MEM_RECLAIM

[Sagi Grimberg]

>> We have three work types:
>> 1. async stuff like namespace scan, aen etc (which can allocate memory)
>> 2. reset which flushes (1) and allocates memory on its own (nvme queues
>> etc...)
>> 3. delete which flushes (2)
>>
>> Maybe it won't be so bad to have three global workqueues to host these
>> works?
> 
> Yes.  Or at least two given that we don't really a private workqueue
> for 1 I think.

We still need it with MEM_RECLAIM because we flush it from the other
workqueues. So we don't need a private workqueue, but we need it with
WQ_MEM_RECLAIM. So either we keep it or introduce system_memreclaim_wq..

Thoughts?