5.4-stable review patch. If anyone has any objections, please let me know.
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From: Roland Xu mu001999@outlook.com
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@outlook.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/ME0P300MB063599BEF0743B8FA339C2CECC802@ME0P300MB... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/locking/rtmutex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1204,6 +1204,7 @@ __rt_mutex_slowlock(struct rt_mutex *loc }
static void rt_mutex_handle_deadlock(int res, int detect_deadlock, + struct rt_mutex *lock, struct rt_mutex_waiter *w) { /* @@ -1213,6 +1214,7 @@ static void rt_mutex_handle_deadlock(int if (res != -EDEADLOCK || detect_deadlock) return;
+ raw_spin_unlock_irq(&lock->wait_lock); /* * Yell lowdly and stop the task right here. */ @@ -1268,7 +1270,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, if (unlikely(ret)) { __set_current_state(TASK_RUNNING); remove_waiter(lock, &waiter); - rt_mutex_handle_deadlock(ret, chwalk, &waiter); + rt_mutex_handle_deadlock(ret, chwalk, lock, &waiter); }
/*