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Fri, 16 Oct 2026 08:04:11 -0700 (PDT) Received: from lima-kdev.local ([85.100.66.184]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1c8ae6d2esm65993715e9.6.2026.10.16.08.04.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Oct 2026 08:04:11 -0700 (PDT) From: Kayra Cizmeci To: peterz@infradead.org, vincent.guittot@linaro.org, Ingo Molnar , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , K Prateek Nayak Cc: christian.loehle@arm.com, elif.topuz@arm.com, linux-kernel@vger.kernel.org, mingo@kernel.org, sh@gentwo.org, Kayra Cizmeci Subject: [PATCH v4] sched/eevdf: Fix vprot across reweighting Date: Fri, 16 Oct 2026 18:04:02 +0300 Message-ID: <20261016150402.6952-1-kayracizmeci@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently in reweighting, while a tasks vruntime changes dead protection could go alive, or alive protection could decrease, increase and go dead. Fix it in reweight_eevdf(), and just cancel it in the sched_change_end() path. Fixes: 80390ead2080 ("sched/fair: Separate se->vlag from se->vprot") Fixes: bcd74b2ffdd0 ("sched/fair: Only set slice protection at pick time") Suggested-by: Vincent Guittot Signed-off-by: Kayra Cizmeci --- Changes v3->v4: * Change enqueue_task_fair() block so that instead of extending the protection in sched_change_end() path just cancel the protection if it is active. (Vincent) v3: https://lore.kernel.org/lkml/20261016084604.17999-1-kayracizmeci@gmail.com/ Compile tested only. kernel/sched/fair.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0feec172fd37..61266c3a7f2f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4892,12 +4892,15 @@ static void reweight_eevdf(struct cfs_rq *cfs_rq, struct sched_entity *se, update_load_set(&se->h_load, weight); if (on_rq) { - if (rel_vprot) - se->vprot += avruntime; se->deadline += avruntime; se->rel_deadline = 0; se->vruntime = avruntime - se->vlag; + if (rel_vprot) + se->vprot += avruntime; + else if (curr) + se->vprot = se->vruntime; + if (!curr) __enqueue_entity(cfs_rq, se); cfs_rq->h_nr_queued++; @@ -8202,6 +8205,13 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (!curr) { reweight_eevdf(cfs_rq, se, weight, false); place_entity(cfs_rq, se, flags | ENQUEUE_QUEUED); + /* + * This happens in sched_change_end(), while cfs_rq->curr == NULL + * and rq->donor == p. In this case, cancel the protection rather + * than extending it. + */ + if (task_current_donor(rq, p)) + cancel_protect_slice(se); __enqueue_entity(cfs_rq, se); } -- 2.53.0