From ee54b5ba72d421a7d51c9d580b7b015b45ff8846 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 23 Jan 2026 16:49:09 +0100 Subject: [PATCH] sched/fair: Only set slice protection at pick time [ Upstream commit bcd74b2ffdd0a2233adbf26b65c62fc69a809c8e ] We should not (re)set slice protection in the sched_change pattern which calls put_prev_task() / set_next_task(). Fixes: 63304558ba5d ("sched/eevdf: Curb wakeup-preemption") Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Vincent Guittot Tested-by: K Prateek Nayak Tested-by: Shubhang Kaushik Link: https://patch.msgid.link/20260219080624.561421378%40infradead.org Signed-off-by: Sasha Levin --- 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 c3735197c6e7..1644ad90acdc 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5477,7 +5477,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) } static void -set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) +set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, bool first) { clear_buddies(cfs_rq, se); @@ -5492,7 +5492,8 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) __dequeue_entity(cfs_rq, se); update_load_avg(cfs_rq, se, UPDATE_TG); - set_protect_slice(cfs_rq, se); + if (first) + set_protect_slice(cfs_rq, se); } update_stats_curr_start(cfs_rq, se); @@ -8932,13 +8933,13 @@ again: pse = parent_entity(pse); } if (se_depth >= pse_depth) { - set_next_entity(cfs_rq_of(se), se); + set_next_entity(cfs_rq_of(se), se, true); se = parent_entity(se); } } put_prev_entity(cfs_rq, pse); - set_next_entity(cfs_rq, se); + set_next_entity(cfs_rq, se, true); __set_next_task_fair(rq, p, true); } @@ -13530,7 +13531,7 @@ static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first) for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); - set_next_entity(cfs_rq, se); + set_next_entity(cfs_rq, se, first); /* ensure bandwidth has been allocated on our new cfs_rq */ account_cfs_rq_runtime(cfs_rq, 0); }