From: Dave Young <dyoung@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>, "Franck Bui" <fbui@suse.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"Ingo Molnar" <mingo@kernel.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Peter Zijlstra" <peterz@infradead.org>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH -v4 2/2] printk: Add kernel parameter to control writes to /dev/kmsg
Date: Mon, 18 Jul 2016 10:18:09 +0800 [thread overview]
Message-ID: <20160718021809.GA6310@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <20160717054035.GA16383@nazgul.tnic>
On 07/17/16 at 07:40am, Borislav Petkov wrote:
> On Sat, Jul 16, 2016 at 06:44:25PM +0800, Dave Young wrote:
>
> ...
>
> > Mis-ratelimit cause critical userspace messages being lost, that is worse
>
> The current setting is quite generous so that all critical messages
> should land in dmesg. Besides, we don't ratelimit during boot. The idea
> is that userspace should switch to a different logging facility once the
> system is up... which userspace does reportedly.
I would say avoiding ratelimit during boot make no much sense. Userspace can not
write to /dev/kmsg when system_state == SYSTEM_BOOTING because init process
has not run yet.
>
> IOW, /dev/kmsg should handle a relatively big logging amount without
> ratelimiting.
>
> > than use off as default. Suppose we turn off devkmsg by default distributions
> > can still turn on it with sysctl and for us who do not want the flooding we can
> > use printk.devkmsg=off in kernel cmdline to override it.
>
> That part I cannot parse.
I do not understand, care to elaborate a bit?
Let me explain my comments, I means to set printk.devkmsg=off by default,
userspace can set it to on by sysctl. User can provide kernel cmdline
printk.devkmsg=off if he/she want.
Or set printk.devkmsg=on by default to avoid break userspace, it is also fine.
>
> > Of course if we turn off it by default we can print a warning to alert user.
> >
> > BTW, for userspace messages maybe they should not go to same log buffer, maybe
> > a separate log buffer for /dev/msg will be better.
>
> See above.
>
Thanks
Dave
next prev parent reply other threads:[~2016-07-18 2:18 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-08 9:18 [PATCH -v4 0/2] printk.devkmsg: Ratelimit it by default Borislav Petkov
2016-07-08 9:18 ` [PATCH -v4 1/2] ratelimit: Extend to print suppressed messages on release Borislav Petkov
2016-07-14 20:29 ` Andrew Morton
2016-07-15 4:00 ` Borislav Petkov
2016-07-08 9:18 ` [PATCH -v4 2/2] printk: Add kernel parameter to control writes to /dev/kmsg Borislav Petkov
2016-07-14 20:23 ` Andrew Morton
2016-07-14 20:39 ` Steven Rostedt
2016-07-15 4:29 ` Borislav Petkov
2016-07-15 6:21 ` Dave Young
2016-07-15 12:45 ` Borislav Petkov
2016-07-16 10:44 ` Dave Young
2016-07-17 5:40 ` Borislav Petkov
2016-07-18 2:18 ` Dave Young [this message]
2016-07-18 4:44 ` Borislav Petkov
2016-07-18 5:20 ` Dave Young
2016-07-18 7:21 ` Borislav Petkov
2016-07-18 7:38 ` Dave Young
2016-07-18 8:08 ` Borislav Petkov
2016-07-18 8:17 ` Dave Young
2016-07-18 9:06 ` Borislav Petkov
2016-07-19 0:35 ` Dave Young
2016-07-19 6:49 ` Borislav Petkov
2016-07-19 7:02 ` Dave Young
2016-07-25 15:18 ` Steven Rostedt
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