[PATCH 5.10 2/4] sched/cpuacct: Fix charge percpu cpuusage

[ovidiu.panait@windriver.com]

From: Chengming Zhou <zhouchengming@bytedance.com>

commit 248cc9993d1cc12b8e9ed716cc3fc09f6c3517dd upstream.

The cpuacct_account_field() is always called by the current task
itself, so it's ok to use __this_cpu_add() to charge the tick time.

But cpuacct_charge() maybe called by update_curr() in load_balance()
on a random CPU, different from the CPU on which the task is running.
So __this_cpu_add() will charge that cputime to a random incorrect CPU.

Fixes: 73e6aafd9ea8 ("sched/cpuacct: Simplify the cpuacct code")
Reported-by: Minye Zhu <zhuminye@bytedance.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220220051426.5274-1-zhouchengming@bytedance.com
Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---
 kernel/sched/cpuacct.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 8a260115a137..3c59c541dd31 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -328,12 +328,13 @@ static struct cftype files[] = {
  */
 void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 {
+	unsigned int cpu = task_cpu(tsk);
 	struct cpuacct *ca;
 
 	rcu_read_lock();
 
 	for (ca = task_ca(tsk); ca; ca = parent_ca(ca))
-		__this_cpu_add(*ca->cpuusage, cputime);
+		*per_cpu_ptr(ca->cpuusage, cpu) += cputime;
 
 	rcu_read_unlock();
 }
-- 
2.31.1