From: Ming Lei <ming.lei@redhat.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] block: blk-mq-sched: Replace GFP_ATOMIC with GFP_KERNEL in blk_mq_sched_assign_ioc
Date: Thu, 25 Jan 2018 13:29:38 +0800 [thread overview]
Message-ID: <20180125052937.GA21712@ming.t460p> (raw)
In-Reply-To: <7a1809ce-c456-0d53-4d3b-2368fb19bfd8@kernel.dk>
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
prev parent reply other threads:[~2018-01-25 5:29 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-25 2:46 [PATCH] block: blk-mq-sched: Replace GFP_ATOMIC with GFP_KERNEL in blk_mq_sched_assign_ioc Jia-Ju Bai
2018-01-25 2:58 ` Al Viro
2018-01-25 3:13 ` Jia-Ju Bai
2018-01-25 4:16 ` Al Viro
2018-01-25 7:52 ` Jia-Ju Bai
2018-01-25 3:34 ` Jens Axboe
2018-01-25 3:40 ` Jia-Ju Bai
2018-01-25 5:29 ` Ming Lei [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180125052937.GA21712@ming.t460p \
--to=ming.lei@redhat.com \
--cc=axboe@kernel.dk \
--cc=baijiaju1990@gmail.com \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.