linux-kernel - Re: [PATCH] cpuset: Make rebuild_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:	Tue, 15 Jul 2008 10:27:49 -0700
From:	Max Krasnyansky <maxk@...lcomm.com>
To:	Paul Menage <menage@...gle.com>
CC:	mingo@...e.hu, pj@....com, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl
Subject: Re: [PATCH] cpuset: Make rebuild_sched_domains() usable from any
 context

Paul Menage wrote:
> On Tue, Jul 15, 2008 at 4:44 AM, Max Krasnyansky <maxk@...lcomm.com> wrote:
>> From: Max Krasnyanskiy <maxk@...lcomm.com>
>>
>> I do not really like the current solution of dropping cgroup lock
>> but it shows what I have in mind in general.
> 
> I think that dropping the cgroup lock will open up races for cpusets.
> The idea of a separate workqueue/thread to do the sched domain
> rebuilding is simplest.

Actually I audited (to the best of my knowledge) all the paths in 
cpusets and rebuild_sched_domains() is the last action. ie We drop the 
lock right after it anyways. It's just it's embedded deep in the call 
stack and therefor I cannot drop it at the higher level.

The only path where I think it's not safe is the cgroup destroy thing 
where we do

cgroup.c
	cgroup_lock();
	for_each_cgroups(...)
		cg->destroy();
	cgroup_unlock();

So in theory it's just that one patch that really needs the workqueue 
trick. But I do agree that it'll make it less tricky across the board.
So I'll pick up you work queue based patch, convert it to single 
threaded, bang on a bit later today and send a patch on top of this one.

Max

--
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/