lkml.org 
[lkml]   [2012]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Attaching a process to cgroups
From
Date
On Mon, 2012-07-23 at 22:41 +0200, Andrea Righi wrote: 
> 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 ;-)
> >
> > -Mike
>
> JFYI,
>
> I'm testing the following patch in a bunch of hosts and I wasn't able to
> make any of them to explode, even running a multi-threaded
> cgroup-intensive workload, but probably I was just lucky (or unlucky,
> depending on the point of view).
>
> It is basically the same Not-signed-off-by work posted by Mike a while
> ago: https://lkml.org/lkml/2011/4/12/599.
>
> In addition, I totally removed the synchronize_rcu() call from
> cgroup_attach_task() and added the call_rcu -> schedule_work removal
> also for css_set. The latter looks unnecessary to me from a logical
> point of view, or maybe I'm missing something, because I can't explain
> why with it I can't trigger any BUG / oops.
>
> Mike, did you make any progress from your old patch?

No, it worked, but I couldn't prove it was really safe, so let it drop.

-Mike



\
 
 \ /
  Last update: 2012-07-24 04:01    [W:0.256 / U:0.184 seconds]
©2003-2014 Jasper Spaans. Advertise on this site