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Message-Id: <1621242249-8314-1-git-send-email-huangzhaoyang@gmail.com>
Date: Mon, 17 May 2021 17:04:09 +0800
From: Huangzhaoyang <huangzhaoyang@...il.com>
To: Johannes Weiner <hannes@...xchg.org>,
Zhaoyang Huang <zhaoyang.huang@...soc.com>,
Ziwei Dai <ziwei.dai@...soc.com>, Ke Wang <ke.wang@...soc.com>,
linux-kernel@...r.kernel.org
Subject: [[RFC]PATCH] psi: fix race between psi_trigger_create and psimon
From: Zhaoyang Huang <zhaoyang.huang@...soc.com>
Race detected between psimon_new and psimon_old as shown below, which
cause panic by accessing invalid psi_system->poll_wait->wait_queue_entry
and psi_system->poll_timer->entry->next. It is not necessary to reinit
resource of psi_system when psi_trigger_create.
psi_trigger_create psimon_new psimon_old
init_waitqueue_head finish_wait
spin_lock(lock_old)
spin_lock_init(lock_new)
wake_up_process(psimon_new)
finish_wait
spin_lock(lock_new)
list_del list_del
Signed-off-by: ziwei.dai <ziwei.dai@...soc.com>
Signed-off-by: ke.wang <ke.wang@...soc.com>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
---
kernel/sched/psi.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index cc25a3c..d00e585 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -182,6 +182,8 @@ struct psi_group psi_system = {
static void psi_avgs_work(struct work_struct *work);
+static void poll_timer_fn(struct timer_list *t);
+
static void group_init(struct psi_group *group)
{
int cpu;
@@ -201,6 +203,8 @@ static void group_init(struct psi_group *group)
memset(group->polling_total, 0, sizeof(group->polling_total));
group->polling_next_update = ULLONG_MAX;
group->polling_until = 0;
+ init_waitqueue_head(&group->poll_wait);
+ timer_setup(&group->poll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->poll_task, NULL);
}
@@ -1157,7 +1161,6 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
return ERR_CAST(task);
}
atomic_set(&group->poll_wakeup, 0);
- init_waitqueue_head(&group->poll_wait);
wake_up_process(task);
timer_setup(&group->poll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->poll_task, task);
@@ -1233,7 +1236,6 @@ static void psi_trigger_destroy(struct kref *ref)
* But it might have been already scheduled before
* that - deschedule it cleanly before destroying it.
*/
- del_timer_sync(&group->poll_timer);
kthread_stop(task_to_destroy);
}
kfree(t);
--
1.9.1
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