Commit 248cc999 authored by Chengming Zhou's avatar Chengming Zhou Committed by Peter Zijlstra
Browse files

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: 73e6aafd ("sched/cpuacct: Simplify the cpuacct code")
Reported-by: default avatarMinye Zhu <zhuminye@bytedance.com>
Signed-off-by: default avatarChengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220220051426.5274-1-zhouchengming@bytedance.com
parent 6255b48a

kernel/sched/cpuacct.c

+2 −1
Original line number Diff line number Diff line
@@ -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();

}