linux-kernel - [PATCH v3] sched/core: fix incorrect cpustat[CPUTIME

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Date:   Sun, 19 Nov 2023 01:12:30 +0800
From:   Cruz Zhao <CruzZhao@...ux.alibaba.com>
To:     mingo@...hat.com, peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, joel@...lfernandes.org
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH v3] sched/core: fix incorrect cpustat[CPUTIME_FORCEIDLE] update

In function __account_forceidle_time(), task_group_account_field()
is called to update kernel_cpustat.cpustat[CPUTIME_FORCEIDLE].
However, p may be not running on current cpu, so update cpustat with
this_cpu_add() is incorrect.

To fix this problem, we get the cpu of p first, and then add delta
to kcpustat_cpu(cpu).cpustat[CPUTIME_FORCEIDLE].

Fixes: 1fcf54deb767 ("sched/core: add forced idle accounting for cgroups")
Signed-off-by: Cruz Zhao <CruzZhao@...ux.alibaba.com>
---
 kernel/sched/cputime.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index af7952f12e6c..8e6d9bf351c2 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -239,9 +239,12 @@ void account_idle_time(u64 cputime)
  */
 void __account_forceidle_time(struct task_struct *p, u64 delta)
 {
+	unsigned int cpu = task_cpu(p);
+
 	__schedstat_add(p->stats.core_forceidle_sum, delta);
 
-	task_group_account_field(p, CPUTIME_FORCEIDLE, delta);
+	kcpustat_cpu(cpu).cpustat[CPUTIME_FORCEIDLE] += delta;
+	cgroup_account_cputime_field(p, CPUTIME_FORCEIDLE, delta);
 }
 #endif
 
-- 
2.39.3