As Peter Zijlstra told me, we have the following path:
do_exit()
exit_itimers()
itimer_delete()
spin_lock_irqsave(&timer->it_lock, &flags);
timer_delete_hook(timer);
kc->timer_del(timer) := posix_cpu_timer_del()
put_task_struct()
__put_task_struct()
task_numa_free()
spin_lock(&grp->lock);
Which means that task_numa_free() can be called with interrupts
disabled, which means that we should not be using spin_lock_irq() but
spin_lock_irqsave() instead. Otherwise we are enabling interrupts while
holding an interrupt unsafe lock!
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Steven Rostedt <[email protected]>
---
v2: let's see if claws mail screws up the format on this on :-p
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7570dd9..3ea16b0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1707,18 +1707,19 @@ no_join:
void task_numa_free(struct task_struct *p)
{
struct numa_group *grp = p->numa_group;
- int i;
void *numa_faults = p->numa_faults_memory;
+ unsigned long flags;
+ int i;
if (grp) {
- spin_lock_irq(&grp->lock);
+ spin_lock_irqsave(&grp->lock, flags);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
grp->faults[i] -= p->numa_faults_memory[i];
grp->total_faults -= p->total_numa_faults;
list_del(&p->numa_entry);
grp->nr_tasks--;
- spin_unlock_irq(&grp->lock);
+ spin_unlock_irqrestore(&grp->lock, flags);
rcu_assign_pointer(p->numa_group, NULL);
put_numa_group(grp);
}
--
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