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[86.130.134.87]) by smtp.gmail.com with ESMTPSA id l1-20020a05600c4f0100b003c6f3f6675bsm17109757wmq.26.2022.11.27.06.18.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 27 Nov 2022 06:18:05 -0800 (PST) From: Qais Yousef To: Ingo Molnar , Peter Zijlstra , Vincent Guittot , Dietmar Eggemann , "Rafael J. Wysocki" , Viresh Kumar Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Lukasz Luba , Wei Wang , Xuewen Yan , Hank , Jonathan JMChen , Qais Yousef Subject: [PATCH 2/3] sched/fair: Fixes for capacity inversion detection Date: Sun, 27 Nov 2022 14:17:41 +0000 Message-Id: <20221127141742.1644023-3-qyousef@layalina.io> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221127141742.1644023-1-qyousef@layalina.io> References: <20221127141742.1644023-1-qyousef@layalina.io> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Traversing the Perf Domains requires rcu_read_lock() to be held and is conditional on sched_energy_enabled(). rcu_read_lock() is held while in load_balance(), add an assert to ensure this is always the case. Also skip capacity inversion detection for our own pd; which was an error. Fixes: 44c7b80bffc3 ("sched/fair: Detect capacity inversion") Reported-by: Dietmar Eggemann Signed-off-by: Qais Yousef (Google) --- kernel/sched/fair.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 89dadaafc1ec..7c0dd57e562a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8856,16 +8856,22 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) * * Thermal pressure will impact all cpus in this perf domain * equally. */ - if (static_branch_unlikely(&sched_asym_cpucapacity)) { + if (sched_energy_enabled()) { unsigned long inv_cap = capacity_orig - thermal_load_avg(rq); struct perf_domain *pd = rcu_dereference(rq->rd->pd); rq->cpu_capacity_inverted = 0; + SCHED_WARN_ON(!rcu_read_lock_held()); + for (; pd; pd = pd->next) { struct cpumask *pd_span = perf_domain_span(pd); unsigned long pd_cap_orig, pd_cap; + /* We can't be inverted against our own pd */ + if (cpumask_test_cpu(cpu_of(rq), pd_span)) + continue; + cpu = cpumask_any(pd_span); pd_cap_orig = arch_scale_cpu_capacity(cpu);