linux-kernel - Re: Futex hash_bucket lock can break isolation and cause priority inversion on RT

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: <20241009072213.GF17263@noisy.programming.kicks-ass.net>
Date: Wed, 9 Oct 2024 09:22:13 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Waiman Long <llong@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Darren Hart <dvhart@...radead.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	André Almeida <andrealmeid@...lia.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-rt-users <linux-rt-users@...r.kernel.org>,
	Valentin Schneider <vschneid@...hat.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Juri Lelli <juri.lelli@...hat.com>
Subject: Re: Futex hash_bucket lock can break isolation and cause priority
 inversion on RT

On Tue, Oct 08, 2024 at 03:44:23PM -0400, Waiman Long wrote:
> 
> On 10/8/24 1:38 PM, Peter Zijlstra wrote:
> > On Tue, Oct 08, 2024 at 04:22:26PM +0100, Juri Lelli wrote:
> > > Does this report make any sense? If it does, has this issue ever been
> > > reported and possibly discussed? I guess it’s kind of a corner case, but
> > > I wonder if anybody has suggestions already on how to possibly try to
> > > tackle it from a kernel perspective.
> > Any shared lock can cause such havoc. Futex hash buckets is just one of
> > a number of very popular ones that's relatively easy to hit.
> > 
> > I do have some futex-numa patches still pending, but they won't
> > magically sure this either. Userspace needs help at the very least.
> 
> Regarding the futex-numa patches, are you planning to get them merged soon?
> We have customers asking for that.

They're on the todo list somewhere... I know Ampere had interest, other
than that nobody really said anything.