linux-kernel - Re: Crashes with 874bbfe600a6 in 3.18.25

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: <1455040613.3604.11.camel@gmail.com>
Date:	Tue, 09 Feb 2016 18:56:53 +0100
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Michal Hocko <mhocko@...nel.org>, Jiri Slaby <jslaby@...e.cz>,
	Thomas Gleixner <tglx@...utronix.de>,
	Petr Mladek <pmladek@...e.com>, Jan Kara <jack@...e.cz>,
	Ben Hutchings <ben@...adent.org.uk>,
	Sasha Levin <sasha.levin@...cle.com>, Shaohua Li <shli@...com>,
	LKML <linux-kernel@...r.kernel.org>,
	stable <stable@...r.kernel.org>,
	Daniel Bilik <daniel.bilik@...system.cz>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: Crashes with 874bbfe600a6 in 3.18.25

On Tue, 2016-02-09 at 12:54 -0500, Tejun Heo wrote:
> Hello, Mike.
> 
> On Tue, Feb 09, 2016 at 06:04:04PM +0100, Mike Galbraith wrote:
> > workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask
> > CPUs
> > 
> > WORK_CPU_UNBOUND work items queued to a bound workqueue always run
> > locally.  This is a good thing normally, but not when the user has
> > asked us to keep unbound work away from certain CPUs.  Round robin
> > these to wq_unbound_cpumask CPUs instead, as perturbation avoidance
> > trumps performance.
> 
> I don't think doing this by default for everyone is a good idea.  A
> lot of workqueue usages tend to touch whatever the scheduler was
> touching after all.  Doing things per-cpu is generally a pretty good
> thing.

It doesn't do anything unless the user twiddles the mask to exclude
certain (think no_hz_full) CPUs, so there are no clueless victims.

	-Mike