linux-kernel - Re: [PATCH 00/12] perf: more fixes

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: <87r3fh8grb.fsf@ashishki-desk.ger.corp.intel.com>
Date:	Fri, 11 Mar 2016 12:12:56 +0200
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
	eranian@...gle.com
Cc:	linux-kernel@...r.kernel.org, vince@...ter.net, dvyukov@...gle.com,
	andi@...stfloor.org, jolsa@...hat.com, panand@...hat.com,
	sasha.levin@...cle.com, oleg@...hat.com,
	Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH 00/12] perf: more fixes

Peter Zijlstra <peterz@...radead.org> writes:

> On Wed, Feb 24, 2016 at 06:45:39PM +0100, Peter Zijlstra wrote:
>
>> With these patches syz-kaller can still trigger some fail; most notably some
>> NMI watchdog triggers and a very sporadic unthrottle bug (much like last time).
>
> So the below seems to make the sporadic unthrottle thing much less
> likely in that I haven't seen it in several hours, my machine keeps
> dying on NMI watchdog bits.
>
> Boris, who has been running syz-kaller on AMD hardware and was hitting a
> very similar bug with the AMD-IBS code, says its not fixed it for him,
> so maybe there's still more to find.
>
> ---
> Subject: perf: Fix unthrottle
>
> Its possible to IOC_PERIOD while the event is throttled, this would
> re-start the event and the next tick would then try to unthrottle it,
> and find the event wasn't actually stopped anymore.
>
> This would tickle a WARN in the x86-pmu code which isn't expecting to
> start a !stopped event.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

FWIW,

Reviewed-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>

Cheers,
--
Alex