Messages in this thread | | | Subject | Re: Attaching a process to cgroups | From | Mike Galbraith <> | Date | Tue, 24 Jul 2012 03:19:15 +0200 |
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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
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