Messages in this thread | | | Date | Wed, 14 Feb 2018 11:36:39 +0100 | From | Juri Lelli <> | Subject | Re: [PATCH V3 04/10] sched/core: Prevent race condition between cpuset and __sched_setscheduler() |
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Hi Mathieu,
On 13/02/18 13:32, Mathieu Poirier wrote: > No synchronisation mechanism exist between the cpuset subsystem and calls > to function __sched_setscheduler(). As such it is possible that new root > domains are created on the cpuset side while a deadline acceptance test > is carried out in __sched_setscheduler(), leading to a potential oversell > of CPU bandwidth. > > By making available the cpuset_mutex to the core scheduler it is possible > to prevent situations such as the one described above from happening. > > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> > ---
[...]
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index f727c3d0064c..0d8badcf1f0f 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4176,6 +4176,13 @@ static int __sched_setscheduler(struct task_struct *p, > } > > /* > + * Make sure we don't race with the cpuset subsystem where root > + * domains can be rebuilt or modified while operations like DL > + * admission checks are carried out. > + */ > + cpuset_lock(); > + > + /*
Mmm, I'm afraid we can't do this. __sched_setscheduler might be called from interrupt contex by normalize_rt_tasks().
Best,
- Juri
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