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sched/core: Add assertions to QUEUE_CLASS

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Add some checks to the sched_change pattern to validate assumptions
around changing classes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20251127154725.771691954@infradead.org
This commit is contained in:
Peter Zijlstra
2025-10-30 12:56:34 +01:00
committed by Ingo Molnar
parent 95a0155224
commit 47efe2ddcc
2 changed files with 14 additions and 0 deletions
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13
kernel/sched/core.c
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@@ -10782,6 +10782,7 @@ struct sched_change_ctx *sched_change_begin(struct task_struct *p, unsigned int
*ctx = (struct sched_change_ctx){ *ctx = (struct sched_change_ctx){
.p = p, .p = p,
.class = p->sched_class,
.flags = flags, .flags = flags,
.queued = task_on_rq_queued(p), .queued = task_on_rq_queued(p),
.running = task_current_donor(rq, p), .running = task_current_donor(rq, p),
@@ -10812,6 +10813,11 @@ void sched_change_end(struct sched_change_ctx *ctx)
lockdep_assert_rq_held(rq); lockdep_assert_rq_held(rq);
/*
* Changing class without *QUEUE_CLASS is bad.
*/
WARN_ON_ONCE(p->sched_class != ctx->class && !(ctx->flags & ENQUEUE_CLASS));
if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to) if ((ctx->flags & ENQUEUE_CLASS) && p->sched_class->switching_to)
p->sched_class->switching_to(rq, p); p->sched_class->switching_to(rq, p);
@@ -10823,6 +10829,13 @@ void sched_change_end(struct sched_change_ctx *ctx)
if (ctx->flags & ENQUEUE_CLASS) { if (ctx->flags & ENQUEUE_CLASS) {
if (p->sched_class->switched_to) if (p->sched_class->switched_to)
p->sched_class->switched_to(rq, p); p->sched_class->switched_to(rq, p);
/*
* If this was a degradation in class someone should have set
* need_resched by now.
*/
WARN_ON_ONCE(sched_class_above(ctx->class, p->sched_class) &&
!test_tsk_need_resched(p));
} else { } else {
p->sched_class->prio_changed(rq, p, ctx->prio); p->sched_class->prio_changed(rq, p, ctx->prio);
} }

1
kernel/sched/sched.h
View File

@@ -3968,6 +3968,7 @@ extern void balance_callbacks(struct rq *rq, struct balance_callback *head);
struct sched_change_ctx { struct sched_change_ctx {
u64 prio; u64 prio;
struct task_struct *p; struct task_struct *p;
const struct sched_class *class;
int flags; int flags;
bool queued; bool queued;
bool running; bool running;