mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-04 01:49:36 +00:00
sched/rt: Fix lockdep annotation within find_lock_lowest_rq()
Roland Dreier reported spurious, hard to trigger lockdep warnings within the scheduler - without any real lockup. This bit gives us the right clue: > [89945.640512] [<ffffffff8103fa1a>] double_lock_balance+0x5a/0x90 > [89945.640568] [<ffffffff8104c546>] push_rt_task+0xc6/0x290 if you look at that code you'll find the double_lock_balance() in question is the one in find_lock_lowest_rq() [yay for inlining]. Now find_lock_lowest_rq() has a bug.. it fails to use double_unlock_balance() in one exit path, if this results in a retry in push_rt_task() we'll call double_lock_balance() again, at which point we'll run into said lockdep confusion. Reported-by: Roland Dreier <roland@kernel.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1337282386.4281.77.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
10717dcde1
commit
7f1b43936f
1 changed files with 1 additions and 1 deletions
|
@ -1562,7 +1562,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
|
|||
task_running(rq, task) ||
|
||||
!task->on_rq)) {
|
||||
|
||||
raw_spin_unlock(&lowest_rq->lock);
|
||||
double_unlock_balance(rq, lowest_rq);
|
||||
lowest_rq = NULL;
|
||||
break;
|
||||
}
|
||||
|
|
Loading…
Reference in a new issue