linux-kernel - Re: Can printk() sleep at runtime?

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Date:   Thu, 31 May 2018 09:32:10 -0500
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     baijiaju1990@...il.com, Bjorn Helgaas <bhelgaas@...gle.com>,
        SergeySenozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Corbet <corbet@....net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>, sboyd@...nel.org,
        Michael Turquette <mturquette@...libre.com>
Subject: Re: Can printk() sleep at runtime?

On Thu, May 31, 2018 at 5:05 AM Petr Mladek <pmladek@...e.com> wrote:
>
> Anyway, we need to fix or remove this format. vsprintf-like functions
> are called in any context and nobody expect that they might sleep.

Ack. I guess the argument is that "%pCr" is rare, and none of *those*
users may care, but I do think that doing things wrong as-is.

It's too subtle to have to know you're in a particular locking context
when you use a particular %p modifier.

                   Linus