Commit b1b9a9d0 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'sched-urgent-2026-03-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull scheduler fix from Ingo Molnar:
 "Fix a DL scheduler bug that may corrupt internal metrics during PI and
  setscheduler() syscalls, resulting in kernel warnings and misbehavior.

  Found during stress-testing"

* tag 'sched-urgent-2026-03-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting
parents 1954c4f0 d658686a

kernel/sched/syscalls.c

+30 −0
Original line number Diff line number Diff line
@@ -284,6 +284,35 @@ static bool check_same_owner(struct task_struct *p) 
		uid_eq(cred->euid, pcred->uid));

}



#ifdef CONFIG_RT_MUTEXES

static inline void __setscheduler_dl_pi(int newprio, int policy,

			      struct task_struct *p,

			      struct sched_change_ctx *scope)

{

	/*

	 * In case a DEADLINE task (either proper or boosted) gets

	 * setscheduled to a lower priority class, check if it neeeds to

	 * inherit parameters from a potential pi_task. In that case make

	 * sure replenishment happens with the next enqueue.

	 */



	if (dl_prio(newprio) && !dl_policy(policy)) {

		struct task_struct *pi_task = rt_mutex_get_top_task(p);



		if (pi_task) {

			p->dl.pi_se = pi_task->dl.pi_se;

			scope->flags |= ENQUEUE_REPLENISH;

		}

	}

}

#else /* !CONFIG_RT_MUTEXES */

static inline void __setscheduler_dl_pi(int newprio, int policy,

			      struct task_struct *p,

			      struct sched_change_ctx *scope)

{

}

#endif /* !CONFIG_RT_MUTEXES */



#ifdef CONFIG_UCLAMP_TASK



static int uclamp_validate(struct task_struct *p,
@@ -655,6 +684,7 @@ int __sched_setscheduler(struct task_struct *p, 
			__setscheduler_params(p, attr);

			p->sched_class = next_class;

			p->prio = newprio;

			__setscheduler_dl_pi(newprio, policy, p, scope);

		}

		__setscheduler_uclamp(p, attr);