[PATCH 6.18 024/314] sched/eevdf: Update se->vprot in reweight_entity()

Sasha Levin
2026-03-10T11:20:57Z

From: Wang Tao <wangtao554@huawei.com>

[ Upstream commit ff38424030f98976150e42ca35f4b00e6ab8fa23 ]

In the EEVDF framework with Run-to-Parity protection, `se->vprot` is an
independent variable defining the virtual protection timestamp.

When `reweight_entity()` is called (e.g., via nice/renice), it performs
the following actions to preserve Lag consistency:
1. Scales `se->vlag` based on the new weight.
2. Calls `place_entity()`, which recalculates `se->vruntime` based on
the new weight and scaled lag.

However, the current implementation fails to update `se->vprot`, leading
to mismatches between the task's actual runtime and its expected duration.

Fixes: 63304558ba5d ("sched/eevdf: Curb wakeup-preemption")
Suggested-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Wang Tao <wangtao554@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Shubhang Kaushik <shubhang@os.amperecomputing.com>
Link: https://patch.msgid.link/20260120123113.3518950-1-wangtao554@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/sched/fair.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1644ad90acdca..8587218ee9073 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3805,6 +3805,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
unsigned long weight)
{
bool curr = cfs_rq->curr == se;
+ bool rel_vprot = false;
+ u64 vprot;

if (se->on_rq) {
/* commit outstanding execution time */
@@ -3812,6 +3814,11 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
update_entity_lag(cfs_rq, se);
se->deadline -= se->vruntime;
se->rel_deadline = 1;
+ if (curr && protect_slice(se)) {
+ vprot = se->vprot - se->vruntime;
+ rel_vprot = true;
+ }
+
cfs_rq->nr_queued--;
if (!curr)
__dequeue_entity(cfs_rq, se);
@@ -3827,6 +3834,9 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
if (se->rel_deadline)
se->deadline = div_s64(se->deadline * se->load.weight, weight);

+ if (rel_vprot)
+ vprot = div_s64(vprot * se->load.weight, weight);
+
update_load_set(&se->load, weight);

do {
@@ -3838,6 +3848,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
enqueue_load_avg(cfs_rq, se);
if (se->on_rq) {
place_entity(cfs_rq, se, 0);
+ if (rel_vprot)
+ se->vprot = se->vruntime + vprot;
update_load_add(&cfs_rq->load, se->load.weight);
if (!curr)
__enqueue_entity(cfs_rq, se);
--
2.51.0