linux-kernel - Re: WARNING: at arch/x86/kernel/cpu/perf

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120206154700.GA13478@elte.hu>
Date:	Mon, 6 Feb 2012 16:47:01 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Markus Trippelsdorf <markus@...ppelsdorf.de>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: WARNING: at arch/x86/kernel/cpu/perf_event.c:989


* Stephane Eranian <eranian@...gle.com> wrote:

> On Mon, Feb 6, 2012 at 3:38 PM, Ingo Molnar <mingo@...e.hu> wrote:
> >
> > * Stephane Eranian <eranian@...gle.com> wrote:
> >
> >> Ok, I found the problem!
> >>
> >> it comes from perf_adjust_freq_unthr_context() vs perf_adjust_period().
> >> The latter can under certain condition stop and restart the event. So we
> >> had:
> >>
> >>       stop()
> >>       if (delta > 0) {
> >>            perf_adjust_period() {
> >>                if (period > 8*...) {
> >>                    stop()
> >>                    ...
> >>                    start()
> >>                }
> >>            }
> >>        }
> >>        start()
> >>
> >> Could have a double stop() and double start(), thus triggering the warning in
> >> x86_pmu_start().
> >>
> >> Will post a patch shortly to fix this.
> >
> > Please send a patch against tip:master (or perf/urgent), on top
> > of:
> >
> >  84f2b9b2edc0: perf: Remove deprecated WARN_ON_ONCE()
> >
> > Note that I updated that patch to removed one more WARN_ON()
> > than you originally sent - please add it back as appropriate, in
> > the delta fix patch.
> >
> I have already added the warning back. Will send against tip:master

Great - thanks!

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/