Re: [RFC PATCH] nvmet-tcp: Don't kmap() pages which can't come from HIGHMEM

From: Keith Busch
Date: Tue Aug 16 2022 - 14:59:59 EST


On Tue, Aug 16, 2022 at 11:18:08AM +0200, Fabio M. De Francesco wrote:
>
> Therefore, I have two questions: am I right about thinking that the pages
> mapped in nvmet_tcp_map_pdu_iovec() are allocated with GFP_KERNEL?

I think you are correct.

> If so, can anyone with more knowledge than mine please say if my changes make
> any sense?

I think it does make sense. I like the code simplification, though this use
was't really paying the kmap penalty since, as you mentioned, this is never
highmem.

You should also remove the cmd's 'nr_mapped' field while you're at it,
otherwise you'll hit the WARN in nvmet_tcp_free_cmd_buffers().