linux-kernel - Re: Attaching a process to cgroups

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: <20120626180620.GK2397@linux.vnet.ibm.com>
Date:	Tue, 26 Jun 2012 11:06:20 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Mike Galbraith <efault@....de>
Cc:	Alexey Vlasov <renton@...ton.name>, linux-kernel@...r.kernel.org
Subject: Re: Attaching a process to cgroups

On Thu, Jun 21, 2012 at 10:23:02AM +0200, Mike Galbraith wrote:
> On Thu, 2012-06-21 at 11:54 +0400, Alexey Vlasov wrote: 
> > On Wed, Jun 20, 2012 at 02:28:18PM +0200, Mike Galbraith wrote:
> > > 
> > > kernel/cgroup.c::cgroup_attach_task()
> > > {
> > > ...
> > > 	synchronize_rcu();
> > > ...
> > > }
> > 
> > So nothing can be done here? (I mean if only I knew how to fix it I
> > wouldn't ask about it ;)
> 
> Sure, kill the obnoxious thing, it's sitting right in the middle of the
> userspace interface.
> 
> I banged on it a while back (wrt explosive android patches), extracted
> RCU from the userspace interface.  It seemed to work great, much faster,
> couldn't make it explode.  I wouldn't bet anything I wasn't willing to
> immediately part with that the result was really really safe though ;-)

Or replace it with synchronize_rcu_expedited().  You can "get lucky"
for quite some time removing synchronize_rcu() calls!

							Thanx, Paul

--
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/