linux-kernel - Re: printk_ratelimited() && proc/sys/kernel/printk

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Message-ID: <CAHk-=wg9-SK6QDhWvgy+7FkV4Q-d0Ae5p3RcAHoKQtRySn9z8g@mail.gmail.com>
Date:   Wed, 20 Mar 2019 10:30:08 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Steffen Froemer <sfroemer@...hat.com>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: Re: printk_ratelimited() && proc/sys/kernel/printk_ratelimit*

On Wed, Mar 20, 2019 at 10:03 AM Oleg Nesterov <oleg@...hat.com> wrote:
>
> At the same time, printk_ratelimited() uses a static ratelimit_state, so user-
> space can't override the default DEFAULT_RATELIMIT_.* numbers.
>
> Isn't it strange? Shouldn't printk_ratelimited() use printk_ratelimit_state ?

No it shouldn't.

Each printk_ratelimited() is independent, and that's very much on purpose.

One screaming printk shouldn't mean that every *other* printk would be shut up.

That said, it's likely true that nobody should really use
printk_ratelimited() anyway. But if two different users do, they
definitely shouldn't then affect each other.

                Linus