cgroup: fix display of forceidle time at root

We need to reset forceidle_sum to 0 when reading from root, since the
bstat we accumulate into is stack allocated.

To make this more robust, just replace the existing cputime reset with a
memset of the overall bstat.

Signed-off-by: Josh Don <joshdon@google.com>
Fixes: 1fcf54deb767 ("sched/core: add forced idle accounting for cgroups")
Cc: stable@vger.kernel.org # v6.0+
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 831f1f4..0a2b496 100644 (file)
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -457,9 +457,7 @@ static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
        struct task_cputime *cputime = &bstat->cputime;
        int i;
 
-       cputime->stime = 0;
-       cputime->utime = 0;
-       cputime->sum_exec_runtime = 0;
+       memset(bstat, 0, sizeof(*bstat));
        for_each_possible_cpu(i) {
                struct kernel_cpustat kcpustat;
                u64 *cpustat = kcpustat.cpustat;