Re: [PATCH] bpf: defer printk() inside __bpf_prog_run()

[John Ogness]

On 2024-06-25, Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
> syzbot is reporting circular locking dependency inside __bpf_prog_run(),
> for fault injection calls printk() despite rq lock is already held.
>
> Guard __bpf_prog_run() using printk_deferred_{enter,exit}() (and
> preempt_{disable,enable}() if CONFIG_PREEMPT_RT=n) in order to defer any
> printk() messages.

Why is the reason for disabling preemption?

John Ogness