Messages in this thread Patch in this message | | | From | Chengming Zhou <> | Subject | [PATCH v3 1/3] sched/cpuacct: fix charge percpu cpuusage | Date | Sun, 20 Feb 2022 13:14:24 +0800 |
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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> --- 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..307800586ac8 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -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(); } -- 2.20.1
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