[PATCH 5.15 561/917] cgroup: Fix rootcg cpu.stat guest double counting

Greg Kroah-Hartman
2021-11-15T23:49:27Z

From: Dan Schatzberg <schatzberg.dan@gmail.com>

[ Upstream commit 81c49d39aea8a10e6d05d3aa1cb65ceb721e19b0 ]

In account_guest_time in kernel/sched/cputime.c guest time is
attributed to both CPUTIME_NICE and CPUTIME_USER in addition to
CPUTIME_GUEST_NICE and CPUTIME_GUEST respectively. Therefore, adding
both to calculate usage results in double counting any guest time at
the rootcg.

Fixes: 936f2a70f207 ("cgroup: add cpu.stat file to root cgroup")
Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/cgroup/rstat.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index b264ab5652ba9..1486768f23185 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -433,8 +433,6 @@ static void root_cgroup_cputime(struct task_cputime *cputime)
cputime->sum_exec_runtime += user;
cputime->sum_exec_runtime += sys;
cputime->sum_exec_runtime += cpustat[CPUTIME_STEAL];
- cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST];
- cputime->sum_exec_runtime += cpustat[CPUTIME_GUEST_NICE];
}
}

--
2.33.0