Re: [PATCH] blk-mq: make synchronous hw_queue runs RT friendly

[Davidlohr Bueso]

On Mon, 13 Dec 2021, Christoph Hellwig wrote:
> But more importantly:  why isn't migrate_disable/enable doing the right
> thing for !PREEMPT_RT to avoid this mess?

Please see Peter's description of the situation in af449901b84.

While I'm not at all a fan of sprinkling migrate_disabling around code,
I didn't want to add any overhead for the common case. If this, however,
were not an issue (if most cases are async runs, for example) the ideal
solution I think would be to just pin current to the hctx->cpumask.

Thanks,
Davidlohr