From: Steven Rostedt <rostedt@goodmis.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ilia Mirkin <imirkin@alum.mit.edu>,
Ingo Molnar <mingo@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Pekka Paalanen <ppaalanen@gmail.com>, Lyude <lyude@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Karol Herbst <kherbst@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
hpa@zytor.com, linux-tip-commits@vger.kernel.org,
Karol Herbst <karolherbst@gmail.com>
Subject: Re: [tip:x86/urgent] x86/mm/kmmio: Fix mmiotrace for page unaligned addresses
Date: Wed, 13 Dec 2017 11:31:35 -0500 [thread overview]
Message-ID: <20171213113135.1a8af60d@gandalf.local.home> (raw)
In-Reply-To: <20171212145105.6rfbdbty6e5ajron@hirez.programming.kicks-ass.net>
On Tue, 12 Dec 2017 15:51:05 +0100
Peter Zijlstra <peterz@infradead.org> wrote:
> On Tue, Dec 12, 2017 at 09:47:05AM -0500, Ilia Mirkin wrote:
> > > So this 'thing' has huge gaping SMP holes in.
> >
> > Sure does! Probably why the following happens when mmiotrace is enabled:
> >
> > void enable_mmiotrace(void)
> > {
> > mutex_lock(&mmiotrace_mutex);
> > if (is_enabled())
> > goto out;
> >
> > if (nommiotrace)
> > pr_info("MMIO tracing disabled.\n");
> > kmmio_init();
> > enter_uniprocessor();
>
> ^^^^^
>
> Ah! I completely missed that. OK, that makes it much less broken :-)
/me just saw this thread.
Once I saw your initial complaint, my first thought was "I think he
doesn't know that it causes the system to turn into a uniprocessor
first".
My ftrace tests have a test that switches to each tracer, and this
mmiotrace catches the most bugs after an rc1 release. The bugs are
triggered by switching to and from uniprocessor mode. Hopefully, with
the new hotplug code, that will be a thing of the past.
>
> If I don't forget, I'll add some comments to this file to clarify that.
Great, thanks!
-- Steve
>
next prev parent reply other threads:[~2017-12-13 16:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 7:51 [PATCH] x86/mm/kmmio: Fix mmiotrace for page unaligned addresses Karol Herbst
2017-12-12 10:55 ` [tip:x86/urgent] " tip-bot for Karol Herbst
2017-12-12 13:49 ` Peter Zijlstra
2017-12-12 14:04 ` Ingo Molnar
2017-12-12 14:21 ` Ilia Mirkin
2017-12-12 14:43 ` Peter Zijlstra
2017-12-12 14:47 ` Ilia Mirkin
2017-12-12 14:51 ` Peter Zijlstra
2017-12-13 16:31 ` Steven Rostedt [this message]
2017-12-12 14:32 ` Karol Herbst
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