linux-kernel - Re: dm crypt: initialize tasklet in crypt_io

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Message-ID: <ZAY/o9ew9AtrCLE5@redhat.com>
Date:   Mon, 6 Mar 2023 14:31:47 -0500
From:   Mike Snitzer <snitzer@...nel.org>
To:     Hou Tao <houtao@...weicloud.com>
Cc:     dm-devel@...hat.com, Alasdair Kergon <agk@...hat.com>,
        Ignat Korchagin <ignat@...udflare.com>,
        linux-kernel@...r.kernel.org, houtao1@...wei.com
Subject: Re: dm crypt: initialize tasklet in crypt_io_init()

On Mon, Mar 06 2023 at  8:49P -0500,
Hou Tao <houtao@...weicloud.com> wrote:

> From: Hou Tao <houtao1@...wei.com>
> 
> When neither no_read_workqueue nor no_write_workqueue are enabled,
> tasklet_trylock() in crypt_dec_pending() may still return false due to
> an uninitialized state, and dm-crypt will do io completion in io_queue
> instead of current context unnecessarily.

Have you actually experienced this?

> Fix it by initializing io->tasklet in crypt_io_init().

Really would rather avoid always calling tasklet_init(). But I can
optimize it away with a later patch.

Mike