linux-kernel - Re: [PATCH] printk: Enough to disable preemption in printk deferred context

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Date:   Wed, 19 Apr 2023 11:11:52 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Petr Mladek <pmladek@...e.com>
Subject: Re: [PATCH] printk: Enough to disable preemption in printk deferred
 context

On 2023-04-19, Petr Mladek <pmladek@...e.com> wrote:
> it is safe to interrupt one writer now. The preemption still
> has to be disabled because the deferred context is CPU specific.

Really it is enough to disable migration.

We need to keep an eye on the usage of this function. By allowing
interrupts and preemption, it means that other printk's on that CPU will
also be deferred if the context interrupted within the deferred block.

John