Merge tag 'locking-urgent-2024-08-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fix from Thomas Gleixner:
"A single fix for rt_mutex.
The deadlock detection code drops into an infinite scheduling loop
while still holding rt_mutex::wait_lock, which rightfully triggers a
'scheduling in atomic' warning.
Unlock it before that"
* tag 'locking-urgent-2024-08-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
rtmutex: Drop rt_mutex::wait_lock before scheduling
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 88d08ee..fba1229 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1644,6 +1644,7 @@
}
static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
+ struct rt_mutex_base *lock,
struct rt_mutex_waiter *w)
{
/*
@@ -1656,10 +1657,10 @@
if (build_ww_mutex() && w->ww_ctx)
return;
- /*
- * Yell loudly and stop the task right here.
- */
+ raw_spin_unlock_irq(&lock->wait_lock);
+
WARN(1, "rtmutex deadlock detected\n");
+
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
rt_mutex_schedule();
@@ -1713,7 +1714,7 @@
} else {
__set_current_state(TASK_RUNNING);
remove_waiter(lock, waiter);
- rt_mutex_handle_deadlock(ret, chwalk, waiter);
+ rt_mutex_handle_deadlock(ret, chwalk, lock, waiter);
}
/*
