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sched_ext: Pass full dequeue flags to ops.quiescent()

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ops.quiescent() is invoked with the same deq_flags as ops.dequeue(), so
the BPF scheduler is able to distinguish sleep vs property changes in
both callbacks.

However, dequeue_task_scx() receives deq_flags as an int from the
sched_class interface, so SCX flags above bit 32 (%SCX_DEQ_SCHED_CHANGE)
are truncated. ops_dequeue() reconstructs the full u64 for ops.dequeue(),
but ops.quiescent() is still called with the original int and can never
see %SCX_DEQ_SCHED_CHANGE.

Fix this by constructing the full u64 deq_flags in dequeue_task_scx()
(renaming the int parameter to core_deq_flags) and passing the complete
flags to both ops_dequeue() and ops.quiescent().

Fixes: ebf1ccff79 ("sched_ext: Fix ops.dequeue() semantics")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Andrea Righi
2026-03-07 10:56:31 +01:00
committed by Tejun Heo
parent f68971bcec
commit 03f5304aad
1 changed files with 10 additions and 10 deletions
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20
kernel/sched/ext.c
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@@ -1782,14 +1782,6 @@ static void ops_dequeue(struct rq *rq, struct task_struct *p, u64 deq_flags)
{
struct scx_sched *sch = scx_task_sched(p);
unsigned long opss;
u64 op_deq_flags = deq_flags;
/*
* Set %SCX_DEQ_SCHED_CHANGE when the dequeue is due to a property
* change (not sleep or core-sched pick).
*/
if (!(op_deq_flags & (DEQUEUE_SLEEP | SCX_DEQ_CORE_SCHED_EXEC)))
op_deq_flags |= SCX_DEQ_SCHED_CHANGE;
/* dequeue is always temporary, don't reset runnable_at */
clr_task_runnable(p, false);
@@ -1846,12 +1838,20 @@ static void ops_dequeue(struct rq *rq, struct task_struct *p, u64 deq_flags)
* NONE but the task may still have %SCX_TASK_IN_CUSTODY set until
* it is enqueued on the destination.
*/
call_task_dequeue(sch, rq, p, op_deq_flags);
call_task_dequeue(sch, rq, p, deq_flags);
}
static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int deq_flags)
static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int core_deq_flags)
{
struct scx_sched *sch = scx_task_sched(p);
u64 deq_flags = core_deq_flags;
/*
* Set %SCX_DEQ_SCHED_CHANGE when the dequeue is due to a property
* change (not sleep or core-sched pick).
*/
if (!(deq_flags & (DEQUEUE_SLEEP | SCX_DEQ_CORE_SCHED_EXEC)))
deq_flags |= SCX_DEQ_SCHED_CHANGE;
if (!(p->scx.flags & SCX_TASK_QUEUED)) {
WARN_ON_ONCE(task_runnable(p));