linux-kernel - Re: [BUG] perf: hard lockup when using perf-sched

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]

Date:	Fri, 26 Mar 2010 20:10:40 +0100
From:	Mike Galbraith <efault@....de>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Li Zefan <lizf@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [BUG] perf: hard lockup when using perf-sched

On Fri, 2010-03-26 at 18:23 +0100, Frederic Weisbecker wrote:
> On Fri, Mar 26, 2010 at 11:11:33AM +0100, Mike Galbraith wrote:

> > perf: fix perf sched record forkbomb deadlock
> > 
> > perf sched record can deadlock a box should the holder of handle->data->lock
> > take an interrupt, and then attempt to acquire an rq lock held by a CPU trying
> > to acquire the same lock.  Disable interrupts.
> 
> 
> 
> Aah.
> 
> So the scenario is the following inversion?
> 
> 	CPU0				CPU1
> sched event with rq->lock held
> 				grab handle->data->lock
> spin on handle->data->lock
> 				interrupt
> 				try to grab rq->lock

Yeah, handle->data->lock holder dare not try to grab any rq lock because
of sched event with rq->lock held.

	-Mike

--
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/