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Re: printk: Add kernel parameter to disable writes to /dev/kmsg

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: printk: Add kernel parameter to disable writes to /dev/kmsg
Date 2016-04-25 21:00 +0200
Message-ID <rrTTI-2ag-23@gated-at.bofh.it> (permalink)
References <rrSbg-172-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Apr 25, 2016 at 01:06:29PM -0400, Steven Rostedt wrote:
> Over the weekend my server was acting funny. The display wasn't working
> well, and I assumed that a driver was going bad. I went to look at the
> kernel dmesg, but the buffer only had the following over and over:
> 
> [226062.401405] systemd-logind[3511]: Removed session 4168.
> [226063.381051] systemd-logind[3511]: Removed session 4169.

> The kernel buffer was completely overridden by useless spewing from

Yes it does this. I usually fix this with: apt-get install sysvinit

> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index bfbf284e4218..b704b48415a0 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -85,6 +85,15 @@ static struct lockdep_map console_lock_dep_map = {
>  };
>  #endif
>  
> +static bool devkmsg_disabled;
> +static int __init disable_devkmsg(char *str)
> +{
> +	devkmsg_disabled = true;
> +	return 0;
> +}
> +__setup("disable_devkmsg_write", disable_devkmsg);
> +

Can't we default enable this? Or at the very least make this easier to
type? I'll never remember how exactly this thing will be called.

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Thread

printk: Add kernel parameter to disable writes to /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 19:10 +0200
  [PATCH] printk: Add kernel parameter to disable writes to /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 19:10 +0200
    Re: [PATCH] printk: Add kernel parameter to disable writes to  /dev/kmsg Borislav Petkov <bp@alien8.de> - 2016-04-25 20:40 +0200
      Re: [PATCH] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 20:50 +0200
  Re: printk: Add kernel parameter to disable writes to /dev/kmsg Peter Zijlstra <peterz@infradead.org> - 2016-04-25 21:00 +0200
  Re: printk: Add kernel parameter to disable writes to /dev/kmsg Pavel Machek <pavel@ucw.cz> - 2016-04-26 20:50 +0200
    Re: printk: Add kernel parameter to disable writes to /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-26 21:50 +0200
      Re: printk: Add kernel parameter to disable writes to /dev/kmsg "Austin S. Hemmelgarn" <ahferroin7@gmail.com> - 2016-04-27 13:30 +0200

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