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Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg

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On Mon, Apr 25, 2016 at 1:00 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
>
> For the purpose to pass messages from early init through to final boot.
> Systemd continued this for the same purpose. Which I agree is totally
> legit. But where systemd fails, is that it continues to use this
> interface far beyond the need.
>
> I agree with Andrew, we should have had a way to close the pipe after
> the system was up and running.

I really don't think this should be about open/close, but about rate
limiting writes.

I think we'd be much better off allowing writes during early boot
(when the real root filesystem hasn't been started yet, so logging to
disk doesn't work - at that point the kernel log really is a better
alternative), and then just start throttling it later (possibly very
aggressively).

But the other issue is that once you actually have logging working, I
don't see why you don't just look at the system logs. Yeah, it's not
/var/log/messages any more, but it's not *that* hard to do. Just use
"journalctl -k" instead of dmesg, and you won't be missing data.

This is why I harp on rate limiting, and I think your patch is silly:
it solves the wrong problem (the one that isn't a real problem), and
it does it with a sledgehammer when a flyswatter would be more
appropriate.

              Linus

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[PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 21:00 +0200
  Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Peter Zijlstra <peterz@infradead.org> - 2016-04-25 21:10 +0200
    Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-25 21:20 +0200
      Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Peter Zijlstra <peterz@infradead.org> - 2016-04-25 21:30 +0200
        Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Andrew Morton <akpm@linux-foundation.org> - 2016-04-25 21:50 +0200
        Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-04-25 22:00 +0200
          Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 22:10 +0200
            Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-25 22:30 +0200
              Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 22:40 +0200
                Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-25 22:50 +0200
                Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 23:30 +0200
              Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Borislav Petkov <bp@alien8.de> - 2016-04-26 13:10 +0200
          Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Peter Zijlstra <peterz@infradead.org> - 2016-04-26 13:20 +0200
      Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 21:40 +0200
    Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-25 21:30 +0200
      Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 21:40 +0200
      Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Linus Torvalds <torvalds@linux-foundation.org> - 2016-04-25 21:40 +0200
      Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Steven Rostedt <rostedt@goodmis.org> - 2016-04-25 21:50 +0200
        Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Ingo Molnar <mingo@kernel.org> - 2016-04-26 07:40 +0200
          Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Bjørn Mork <bjorn@mork.no> - 2016-04-26 12:50 +0200
            Re: [PATCH v2] printk: Add kernel parameter to disable writes to  /dev/kmsg Peter Zijlstra <peterz@infradead.org> - 2016-04-26 13:10 +0200
  Re: [PATCH v2] printk: Add kernel parameter to disable writes to /dev/kmsg Andi Kleen <andi@firstfloor.org> - 2016-04-25 21:50 +0200

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