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A single fix for rt_mutex:

Browse Source 
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.
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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
This commit is contained in:
Linus Torvalds 2024-09-01 14:26:33 -07:00
commit 51859c5aa6
1 changed files with 5 additions and 4 deletions
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9
kernel/locking/rtmutex.c
View File

@ -1644,6 +1644,7 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
}
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 @@ static void __sched rt_mutex_handle_deadlock(int res, int detect_deadlock,
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 @@ static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
} 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);
}
/*