linux-kernel - Re: [RFC][PATCH] printk: increase devkmsg write() ratelimit

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Date:   Wed, 19 Dec 2018 01:52:17 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] printk: increase devkmsg write() ratelimit

On (12/18/18 16:24), Borislav Petkov wrote:
> On Wed, Dec 19, 2018 at 12:14:55AM +0900, Sergey Senozhatsky wrote:
> > Right, but unlike log_buf_len, devkmsg is a bit close to a "binary" knob:
> > either all messages or none;
> 
> ... which is perfectly fine for a debugging session.

But devkmsg ratelimits systemd errors, so one does not even know that
"some debugging is required". For instance from my x86 box:

 Unmounting /home...
 [..]
 home.mount: Mount process exited, code=exited status=32
 Failed unmounting /home.

I don't want to debug systemd, I want to know that something didn't
work out. 10 messages max and 5 seconds interval looks a bit too strict.

	-ss