[PATCH 5.16 0269/1017] sched/cpuacct: Fix charge percpu cpuusage

Greg Kroah-Hartman
2022-04-05T09:13:24Z

From: Chengming Zhou <zhouchengming@bytedance.com>

[ Upstream commit 248cc9993d1cc12b8e9ed716cc3fc09f6c3517dd ]

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: Sasha Levin <sashal@kernel.org>
---
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 ab67d97a8442..cacc2076ad21 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();
}
--
2.34.1