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sched/cpuacct: Fix charge percpu cpuusage 

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: 73e6aafd9e ("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
This commit is contained in:
Chengming Zhou 2022-02-20 13:14:24 +08:00 committed by Peter Zijlstra
parent 6255b48aeb
commit 248cc9993d
1 changed files with 2 additions and 1 deletions
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3
kernel/sched/cpuacct.c
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@ -334,12 +334,13 @@ 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();
}