[lvs-users] LVS kernel panic

Alexander Vasiliev a.vasylev at 404-group.com
Fri Jun 19 08:53:56 BST 2015

Thanks, for answer. I will use -D ==> -A for edit services.

> On Jun 18, 2015, at 9:52 PM, Julian Anastasov <ja at ssi.bg> wrote:
> 	Hello,
> On Thu, 18 Jun 2015, Alexander Vasiliev wrote:
>> Hello.
>> I have installed ipvsadm (1.2.1) on Linux Ubuntu-14.04 (3.13.0-55-generic) server.
>> Next I create service: ipvsadm -A -t -s lblc.
>> When I tried edit created service I got kernel panic. Edit command: ipvsadm -A -t -s rr, for example.
>> The problem is repeatable, I try in VirtualBox.
> 	You mean second command is -E, not -A, right?
> It looks like I completely messed the scheduler editing
> with commit ceec4c381681 ("ipvs: convert services to rcu").
> The problem is with the svc->sched_data. I forgot about it.
> The reverse order of ip_vs_bind_scheduler and
> ip_vs_unbind_scheduler causes problem in all cases
> for schedulers that maintain sched_data.
> And RCU readers are not guaranteed to get the
> scheduler+sched_data pointers safely for same scheduler.
> 	The simple fix would be to make sure
> ip_vs_unbind_scheduler and ip_vs_bind_scheduler work
> in this order but with synchronize_rcu between them.
> Something like what was before this change.
> The individual schedulers will not be touched.
> As changing of scheduler is a rare operation it can
> be the initial bugfix. If we want to fix it without
> such delay we have to change all schedulers, may be
> by moving sched_data in some new struct scheduler_context
> where schedulers can store their sched_data. Then
> svc->sched_context (RCU ptr) can contain both the
> scheduler and the sched_data pointers.
> Regards
> --
> Julian Anastasov <ja at ssi.bg>

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