All of lore.kernel.org
 help / color / mirror / Atom feed
From: David Ahern <dsahern@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Jones <davej@redhat.com>,
	paulmck@linux.vnet.ibm.com,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: suspicious RCU usage (perf)
Date: Tue, 27 Aug 2013 07:58:12 -0600	[thread overview]
Message-ID: <521CB074.3040900@gmail.com> (raw)
In-Reply-To: <20130827091011.18ed8b59@gandalf.local.home>

On 8/27/13 7:10 AM, Steven Rostedt wrote:
> On Mon, 26 Aug 2013 15:49:24 -0400
> Dave Jones <davej@redhat.com> wrote:
>
>
>>   > Do you have /sys/kernel/debug with access permissions?
>>
>> Ah, yeah, that'll be it. Good catch.
>>
>> Sorry for the false alarm Steve ;)
>
> Yeah, but it still does not explain how perf got started. Perf requires
> a sys_perf_event_open() call to run.

Per Peter's response another option is the paranoia level:

# perf event paranoia level:
# -1 - not paranoid at all
#  0 - disallow raw tracepoint access for unpriv
#  1 - disallow cpu events for unpriv
#  2 - disallow kernel profiling for unpriv
kernel.perf_event_paranoid = -1

I keep my dev box at -1 and set /sys/kernel/debug to 755 to run perf as 
non-root.

David

  reply	other threads:[~2013-08-27 13:58 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-26 14:58 suspicious RCU usage (perf) Dave Jones
2013-08-26 16:29 ` Paul E. McKenney
2013-08-26 17:30   ` Steven Rostedt
2013-08-26 17:50     ` Dave Jones
2013-08-26 18:18       ` Steven Rostedt
2013-08-26 18:29         ` Dave Jones
2013-08-26 19:03           ` Steven Rostedt
2013-08-27 12:16             ` Peter Zijlstra
2013-08-30 15:49               ` Frederic Weisbecker
2013-08-30 15:52               ` Frederic Weisbecker
2013-08-30 15:59                 ` Peter Zijlstra
2013-08-30 16:06                   ` Frederic Weisbecker
2013-08-26 19:43           ` David Ahern
2013-08-26 19:49             ` Dave Jones
2013-08-27 13:10               ` Steven Rostedt
2013-08-27 13:58                 ` David Ahern [this message]
2013-08-27 14:13                   ` Dave Jones

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=521CB074.3040900@gmail.com \
    --to=dsahern@gmail.com \
    --cc=davej@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=rostedt@goodmis.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.