linux-kernel - Re: [PATCH 1/1] hotplug cpu: migrate a task within its cpuset

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: <20070310170819.GA26772@elte.hu>
Date:	Sat, 10 Mar 2007 18:08:19 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Nathan Lynch <ntl@...ox.com>
Cc:	Cliff Wickman <cpw@....com>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/1] hotplug cpu: migrate a task within its cpuset


* Nathan Lynch <ntl@...ox.com> wrote:

> > > +	/* try to stay on the same cpuset */
> > > +	if (dest_cpu == NR_CPUS) {
> > > +		p->cpus_allowed = cpuset_cpus_allowed(p);
> > > +		dest_cpu = any_online_cpu(p->cpus_allowed);
> > > +	}
> > 
> > what's the practical effect of this - when moving the last CPU offline 
> > from a node you got jobs migrated to really alien nodes? Thus i think we 
> > should queue this up for v2.6.21 too, correct? It's a NOP on systems 
> > that do not set up cpusets, so it's low-risk.
> 
> See my earlier reply to this patch.  Calling cpuset_cpus_allowed 
> (which takes a mutex) here is a bug, since move_task_off_dead_cpu must 
> be called with interrupts disabled.

ouch. i only checked the !CONFIG_CPUSET case :-/ It's a really bad idea 
to have any locking there indeed. The name itself suggests some atomic 
action.

	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/