From: Peter Zijlstra <peterz@infradead.org>
Even though sched_submit_work() is ran from preemptible context,
it is discouraged to have it use blocking locks due to the recursion
potential.
Enforce this.
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230815111430.154558666@infradead.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/sched/core.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c52c2eba7c739..bca53ff9d8182 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6735,11 +6735,18 @@ void __noreturn do_task_dead(void)
static inline void sched_submit_work(struct task_struct *tsk)
{
+ static DEFINE_WAIT_OVERRIDE_MAP(sched_map, LD_WAIT_CONFIG);
unsigned int task_flags;
if (task_is_running(tsk))
return;
+ /*
+ * Establish LD_WAIT_CONFIG context to ensure none of the code called
+ * will use a blocking primitive -- which would lead to recursion.
+ */
+ lock_map_acquire_try(&sched_map);
+
task_flags = tsk->flags;
/*
* If a worker goes to sleep, notify and ask workqueue whether it
@@ -6764,6 +6771,8 @@ static inline void sched_submit_work(struct task_struct *tsk)
* make sure to submit it to avoid deadlocks.
*/
blk_flush_plug(tsk->plug, true);
+
+ lock_map_release(&sched_map);
}
static void sched_update_worker(struct task_struct *tsk)
--
2.40.1