Re: [PATCH] block: blk-mq-sched: Replace GFP_ATOMIC with GFP_KERNEL in blk_mq_sched_assign_ioc

[Ming Lei]

On Wed, Jan 24, 2018 at 08:34:14PM -0700, Jens Axboe wrote:
> On 1/24/18 7:46 PM, Jia-Ju Bai wrote:
> > The function ioc_create_icq here is not called in atomic context.
> > Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
> > 
> > This is found by a static analysis tool named DCNS written by myself.
> 
> But it's running off the IO submission path, so by definition the GFP
> mask cannot include anything that will do IO. GFP_KERNEL will make
> it deadlock prone.
> 
> It could be GFP_NOIO, but that's also overlooking the fact that we can
> have preemption disabled here.

We have REQ_NOWAIT request too, so GFP_NOIO isn't OK too.

-- 
Ming