Messages in this thread | | | Date | Thu, 25 Jan 2018 13:29:38 +0800 | From | Ming Lei <> | Subject | Re: [PATCH] block: blk-mq-sched: Replace GFP_ATOMIC with GFP_KERNEL in blk_mq_sched_assign_ioc |
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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
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