Commit 28bc55f6 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched: Constrain locks in sched_submit_work() 



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: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-2-bigeasy@linutronix.de
parent a432b7c0

kernel/sched/core.c

+9 −0
Original line number Diff line number Diff line
@@ -6720,11 +6720,18 @@ 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
@@ -6749,6 +6756,8 @@ 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)