Messages in this thread Patch in this message | | | Date | Wed, 21 May 2014 18:49:59 +0200 | From | Peter Zijlstra <> | Subject | Re: sched: spinlock recursion in migrate_swap_stop |
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On Wed, May 21, 2014 at 03:19:48PM +0200, Peter Zijlstra wrote: > On Wed, May 21, 2014 at 09:08:26AM -0400, Sasha Levin wrote:
> > +++ b/kernel/sched/core.c > > @@ -1154,6 +1156,7 @@ int migrate_swap(struct task_struct *cur, struct task_struct *p) > > goto out; > > > > trace_sched_swap_numa(cur, arg.src_cpu, p, arg.dst_cpu); > > + BUG_ON(cur == p); > > ret = stop_two_cpus(arg.dst_cpu, arg.src_cpu, migrate_swap_stop, &arg); > > > > out: > > > > > > Which seems to get hit. This sounds like a race with task moving to > > other cpu maybe? > > Oi, good call that, lemme go stare.
I think something simple like this should be sufficient to avoid the problem of selecting oneself as a flip target.
--- kernel/sched/fair.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 28ccf502c63c..28ba71d815ee 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1115,6 +1115,8 @@ static void task_numa_compare(struct task_numa_env *env, cur = ACCESS_ONCE(dst_rq->curr); if (cur->pid == 0) /* idle */ cur = NULL; + if (cur == env->p) + goto unlock; /* * "imp" is the fault differential for the source task between the
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