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Subject[PATCH] sched/cpuacct: fix charge percpu cpuusage
Date
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.

Reported-by: Minye Zhu <zhuminye@bytedance.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.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 3d06c5e4220d..75fbc212cb71 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -335,11 +335,12 @@ static struct cftype files[] = {
void cpuacct_charge(struct task_struct *tsk, u64 cputime)
{
struct cpuacct *ca;
+ unsigned int cpu = task_cpu(tsk);

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();
}
--
2.20.1
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