6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Roland Xu <mu001999@xxxxxxxxxxx>
commit d33d26036a0274b472299d7dcdaa5fb34329f91b upstream.
rt_mutex_handle_deadlock() is called with rt_mutex::wait_lock held. In the
good case it returns with the lock held and in the deadlock case it emits a
warning and goes into an endless scheduling loop with the lock held, which
triggers the 'scheduling in atomic' warning.
Unlock rt_mutex::wait_lock in the dead lock case before issuing the warning
and dropping into the schedule for ever loop.
[ tglx: Moved unlock before the WARN(), removed the pointless comment,
massaged changelog, added Fixes tag ]
Fixes: 3d5c9340d194 ("rtmutex: Handle deadlock detection smarter")
Signed-off-by: Roland Xu <mu001999@xxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/ME0P300MB063599BEF0743B8FA339C2CECC802@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/locking/rtmutex.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1624,6 +1624,7 @@ static int __sched rt_mutex_slowlock_blo
}
static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
+ struct rt_mutex_base *lock,
struct rt_mutex_waiter *w)
{
/*
@@ -1636,10 +1637,10 @@ static void __sched rt_mutex_handle_dead
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);
schedule();
@@ -1693,7 +1694,7 @@ static int __sched __rt_mutex_slowlock(s
} 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);
}
/*
