1. read_lock(tasklist_lock) does not need to disable irqs.
2. ->mm != NULL is the common mistake, use PF_KTHREAD.
3. The second ->mm check can be simply removed.
4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) +
__task_rq_lock().
Signed-off-by: Oleg Nesterov <o...@redhat.com>
---
kernel/sched/core.c | 16 ++++++----------
1 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8a6506f..eee12b3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7137,12 +7137,12 @@ void normalize_rt_tasks(void)
unsigned long flags;
struct rq *rq;
- read_lock_irqsave(&tasklist_lock, flags);
+ read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
/*
* Only normalize user tasks:
*/
- if (!p->mm)
+ if (p->flags & PF_KTHREAD)
continue;
p->se.exec_start = 0;
@@ -7157,20 +7157,16 @@ void normalize_rt_tasks(void)
* Renice negative nice level userspace
* tasks back to 0:
*/
- if (task_nice(p) < 0 && p->mm)
+ if (task_nice(p) < 0)
set_user_nice(p, 0);
continue;
}
- raw_spin_lock(&p->pi_lock);
- rq = __task_rq_lock(p);
-
+ rq = task_rq_lock(p, &flags);
normalize_task(rq, p);
-
- __task_rq_unlock(rq);
- raw_spin_unlock(&p->pi_lock);
+ task_rq_unlock(rq, p, &flags);
}
- read_unlock_irqrestore(&tasklist_lock, flags);
+ read_unlock(&tasklist_lock);
}
#endif /* CONFIG_MAGIC_SYSRQ */
--
1.5.5.1
--
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