HWPOISON: Allow schedule_on_each_cpu() from keventd
Right now when calling schedule_on_each_cpu() from keventd there
is a deadlock because it tries to schedule a work item on the current CPU
too. This happens via lru_add_drain_all() in hwpoison.
Just call the function for the current CPU in this case. This is actually
faster too.
Debugging with Fengguang Wu & Max Asbock
Signed-off-by: Andi Kleen <ak@linux.intel.com>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index addfe2d..f61a2fe 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -667,21 +667,38 @@
int schedule_on_each_cpu(work_func_t func)
{
int cpu;
+ int orig = -1;
struct work_struct *works;
works = alloc_percpu(struct work_struct);
if (!works)
return -ENOMEM;
+ /*
+ * when running in keventd don't schedule a work item on itself.
+ * Can just call directly because the work queue is already bound.
+ * This also is faster.
+ * Make this a generic parameter for other workqueues?
+ */
+ if (current_is_keventd()) {
+ orig = raw_smp_processor_id();
+ INIT_WORK(per_cpu_ptr(works, orig), func);
+ func(per_cpu_ptr(works, orig));
+ }
+
get_online_cpus();
for_each_online_cpu(cpu) {
struct work_struct *work = per_cpu_ptr(works, cpu);
+ if (cpu == orig)
+ continue;
INIT_WORK(work, func);
schedule_work_on(cpu, work);
}
- for_each_online_cpu(cpu)
- flush_work(per_cpu_ptr(works, cpu));
+ for_each_online_cpu(cpu) {
+ if (cpu != orig)
+ flush_work(per_cpu_ptr(works, cpu));
+ }
put_online_cpus();
free_percpu(works);
return 0;
