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From: Petr Mladek <pmladek@suse.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: "Luis R. Rodriguez" <mcgrof@kernel.org>,
	shuah@kernel.org, jeyu@redhat.com, rusty@rustcorp.com.au,
	ebiederm@xmission.com, acme@redhat.com, corbet@lwn.net,
	martin.wilck@suse.com, mmarek@suse.com, hare@suse.com,
	rwright@hpe.com, jeffm@suse.com, DSterba@suse.com,
	fdmanana@suse.com, neilb@suse.com, linux@roeck-us.net,
	rgoldwyn@suse.com, subashab@codeaurora.org, xypron.glpk@gmx.de,
	keescook@chromium.org, atomlin@redhat.com, mbenes@suse.cz,
	paulmck@linux.vnet.ibm.com, dan.j.williams@intel.com,
	jpoimboe@redhat.com, davem@davemloft.net, mingo@redhat.com,
	akpm@linux-foundation.org, torvalds@linux-foundation.org,
	gregkh@linuxfoundation.org, linux-kselftest@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] kmod: use simplified rate limit printk
Date: Tue, 23 May 2017 11:00:57 +0200
Message-ID: <20170523090057.GB26699@pathway.suse.cz> (raw)
In-Reply-To: <20170519222327.GH19281@dtor-ws>

On Fri 2017-05-19 15:23:27, Dmitry Torokhov wrote:
> On Thu, May 18, 2017 at 08:24:44PM -0700, Luis R. Rodriguez wrote:
> > Just use the simplified rate limit printk when the max modprobe
> > limit is reached, while at it throw out a bone should the error
> > be triggered.
> > 
> > Reviewed-by: Petr Mladek <pmladek@suse.com>
> > Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
> > ---
> >  kernel/kmod.c | 10 ++--------
> >  1 file changed, 2 insertions(+), 8 deletions(-)
> > 
> > diff --git a/kernel/kmod.c b/kernel/kmod.c
> > index 7ea11dbc7564..56cd2a16e7ac 100644
> > --- a/kernel/kmod.c
> > +++ b/kernel/kmod.c
> > @@ -166,7 +166,6 @@ int __request_module(bool wait, const char *fmt, ...)
> >  	va_list args;
> >  	char module_name[MODULE_NAME_LEN];
> >  	int ret;
> > -	static int kmod_loop_msg;
> >  
> >  	/*
> >  	 * We don't allow synchronous module loading from async.  Module
> > @@ -191,13 +190,8 @@ int __request_module(bool wait, const char *fmt, ...)
> >  
> >  	ret = kmod_umh_threads_get();
> >  	if (ret) {
> > -		/* We may be blaming an innocent here, but unlikely */
> > -		if (kmod_loop_msg < 5) {
> > -			printk(KERN_ERR
> > -			       "request_module: runaway loop modprobe %s\n",
> > -			       module_name);
> > -			kmod_loop_msg++;
> > -		}
> > +		pr_err_ratelimited("%s: module \"%s\" reached limit (%u) of concurrent modprobe calls\n",
> > +				   __func__, module_name, max_modprobes);
> 
> This is completely different behavior, isn't it? Instead of reporting
> first 5 occurrences we now reporting every once in a while. Why is this
> new behavior better?

pr_err_ratelimited() shows the first 10 messages by default,
see DEFAULT_RATELIMIT_BURST. In addition, it allows to see
the messages again after some time (5 sec by default).
Therefore you could see if the bad situation persists or if
the limit was reached more times during the system lifetime.

Best Regards,
Petr

  reply index

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-19  3:24 [PATCH 0/6] kmod: few simple enhancements Luis R. Rodriguez
2017-05-19  3:24 ` [PATCH 1/6] kmod: add dynamic max concurrent thread count Luis R. Rodriguez
2017-05-19 20:44   ` Dmitry Torokhov
     [not found]     ` <CAB=NE6XGL24O+JfTNUG0HO4obhDc-v+HyL0SCrQELiZrj2-qNw@mail.gmail.com>
     [not found]       ` <CAB=NE6Wa4Nemh80yaCCwbjrNRLPD+GJMncg12APg9Vq63AWVng@mail.gmail.com>
     [not found]         ` <CAB=NE6Vc6RDAytn2Pkv2V58HFo8ncR0eOHZ3===kbZ2NF78ubg@mail.gmail.com>
     [not found]           ` <CAB=NE6Vqmx=y6muenpuQKynTP=pGWMF8tzoCA0BXD6d63q9wPg@mail.gmail.com>
2017-05-19 21:58             ` Dmitry Torokhov
2017-05-25 16:22               ` Luis R. Rodriguez
2017-05-25 16:38                 ` Dmitry Torokhov
2017-05-25 16:50                   ` Luis R. Rodriguez
2017-05-25 17:30                     ` Dmitry Torokhov
2017-05-25 17:38                       ` Luis R. Rodriguez
2017-05-25 18:06                         ` Luis R. Rodriguez
2017-05-25 18:26                           ` Dmitry Torokhov
2017-05-25 19:01                             ` Luis R. Rodriguez
2017-05-25 21:38                               ` Luis R. Rodriguez
2017-05-19  3:24 ` [PATCH 2/6] module: use list_for_each_entry_rcu() on find_module_all() Luis R. Rodriguez
2017-05-23 14:46   ` Miroslav Benes
2017-05-19  3:24 ` [PATCH 3/6] kmod: provide wrappers for kmod_concurrent inc/dec Luis R. Rodriguez
2017-05-19  3:24 ` [PATCH 4/6] kmod: return -EBUSY if modprobe limit is reached Luis R. Rodriguez
2017-05-19  3:24 ` [PATCH 5/6] kmod: preempt on kmod_umh_threads_get() Luis R. Rodriguez
2017-05-19 22:27   ` Dmitry Torokhov
2017-05-25  0:14     ` Luis R. Rodriguez
2017-05-25  0:45       ` Dmitry Torokhov
2017-05-25  1:00         ` Luis R. Rodriguez
2017-05-25  2:27           ` Dmitry Torokhov
2017-05-25 11:19             ` Petr Mladek
2017-05-25 15:38               ` Luis R. Rodriguez
2017-05-25 16:42               ` Dmitry Torokhov
2017-05-25 15:18             ` Jessica Yu
2017-05-19  3:24 ` [PATCH 6/6] kmod: use simplified rate limit printk Luis R. Rodriguez
2017-05-19 22:23   ` Dmitry Torokhov
2017-05-23  9:00     ` Petr Mladek [this message]
2017-05-26  0:16 ` [PATCH v2 0/5] kmod: help make deterministic Luis R. Rodriguez
2017-05-26  0:16   ` [PATCH v2 1/5] module: use list_for_each_entry_rcu() on find_module_all() Luis R. Rodriguez
2017-05-26  0:16   ` [PATCH v2 2/5] kmod: reduce atomic operations on kmod_concurrent Luis R. Rodriguez
2017-05-26  1:11     ` Dmitry Torokhov
2017-05-26 20:03       ` Luis R. Rodriguez
2017-05-26  0:16   ` [PATCH v2 3/5] kmod: add test driver to stress test the module loader Luis R. Rodriguez
2017-05-26  0:16   ` [PATCH v2 4/5] kmod: add helpers for getting kmod limit Luis R. Rodriguez
2017-05-26  0:56     ` Dmitry Torokhov
2017-05-26 20:27       ` Luis R. Rodriguez
2017-05-26  0:16   ` [PATCH v2 5/5] kmod: throttle kmod thread limit Luis R. Rodriguez
2017-05-26 21:12   ` [PATCH v3 0/4] kmod: help make deterministic Luis R. Rodriguez
2017-05-26 21:12     ` [PATCH v3 1/4] module: use list_for_each_entry_rcu() on find_module_all() Luis R. Rodriguez
2017-05-26 21:12     ` [PATCH v3 2/4] kmod: reduce atomic operations on kmod_concurrent and simplify Luis R. Rodriguez
2017-06-23 19:19       ` [PATCH v4 " Luis R. Rodriguez
2017-06-26 11:36       ` [PATCH v3 " Petr Mladek
2017-05-26 21:12     ` [PATCH v3 3/4] kmod: add test driver to stress test the module loader Luis R. Rodriguez
2017-05-26 21:12     ` [PATCH v3 4/4] kmod: throttle kmod thread limit Luis R. Rodriguez
2017-06-22 15:19       ` Petr Mladek
2017-06-23 16:16         ` Luis R. Rodriguez
2017-06-23 17:56           ` Luis R. Rodriguez
2017-06-23 19:16             ` Luis R. Rodriguez
2017-06-26 10:03               ` Petr Mladek
2017-06-26  9:55           ` Petr Mladek
2017-06-23 19:20       ` [PATCH v4 " Luis R. Rodriguez
2017-06-26 11:38         ` Petr Mladek
2017-06-28 22:11           ` Luis R. Rodriguez
2017-06-20 20:56     ` [PATCH v3 0/4] kmod: help make deterministic Luis R. Rodriguez
2017-06-21  0:23       ` Kees Cook
2017-06-26 21:37         ` Jessica Yu
2017-06-26 22:44           ` Luis R. Rodriguez
2017-06-27  0:27             ` Luis R. Rodriguez
2017-06-27  8:13               ` Petr Mladek
2017-06-27 10:04                 ` Jessica Yu
2017-06-27 15:26             ` Jessica Yu
2017-06-28  0:49               ` Luis R. Rodriguez
2017-06-28 22:31     ` [PATCH v4 0/3] " Luis R. Rodriguez
2017-06-28 22:31       ` [PATCH v4 1/3] MAINTAINERS: give kmod some maintainer love Luis R. Rodriguez
2017-06-28 22:31       ` [PATCH v4 2/3] kmod: add test driver to stress test the module loader Luis R. Rodriguez
2017-06-28 22:31       ` [PATCH v4 3/3] kmod: throttle kmod thread limit Luis R. Rodriguez

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