6.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tianchen Ding dtcccc@linux.alibaba.com
[ Upstream commit afae8002b4fd3560c8f5f1567f3c3202c30a70fa ]
reweight_eevdf() only keeps V unchanged inside itself. When se != cfs_rq->curr, it would be dequeued from rb tree first. So that V is changed and the result is wrong. Pass the original V to reweight_eevdf() to fix this issue.
Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight") Signed-off-by: Tianchen Ding dtcccc@linux.alibaba.com [peterz: flip if() condition for clarity] Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Abel Wu wuyun.abel@bytedance.com Link: https://lkml.kernel.org/r/20240306022133.81008-3-dtcccc@linux.alibaba.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/sched/fair.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 69d2158873429..b9ee4397b484a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3670,11 +3670,10 @@ static inline void dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { } #endif
-static void reweight_eevdf(struct cfs_rq *cfs_rq, struct sched_entity *se, +static void reweight_eevdf(struct sched_entity *se, u64 avruntime, unsigned long weight) { unsigned long old_weight = se->load.weight; - u64 avruntime = avg_vruntime(cfs_rq); s64 vlag, vslice;
/* @@ -3781,24 +3780,26 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, unsigned long weight) { bool curr = cfs_rq->curr == se; + u64 avruntime;
if (se->on_rq) { /* commit outstanding execution time */ update_curr(cfs_rq); + avruntime = avg_vruntime(cfs_rq); if (!curr) __dequeue_entity(cfs_rq, se); update_load_sub(&cfs_rq->load, se->load.weight); } dequeue_load_avg(cfs_rq, se);
- if (!se->on_rq) { + if (se->on_rq) { + reweight_eevdf(se, avruntime, weight); + } else { /* * Because we keep se->vlag = V - v_i, while: lag_i = w_i*(V - v_i), * we need to scale se->vlag when w_i changes. */ se->vlag = div_s64(se->vlag * se->load.weight, weight); - } else { - reweight_eevdf(cfs_rq, se, weight); }
update_load_set(&se->load, weight);