The commit is pushed to "branch-rh9-5.14.0-162.6.1.vz9.18.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-162.6.1.vz9.18.2
------>
commit 6555547a385aa5c76feddee263bd1f04e8228b89
Author: Nikolay Borisov <nikolay.bori...@virtuozzo.com>
Date: Wed Nov 30 14:29:25 2022 +0200
loadavg: Fix handling of cfs_rq->nr_unint values
Our custom nr_unint logic follows the kernel's one about the global
nr_uninterruptible one. One invariant that both share is that values
of nr_unint can go negative when a task is migrated from a CPU.
What's important is that when summed across all task groups they either
result
in a positive number (we have sleeping tasks in uninterruptible state) or 0
(no uninterruptible processes).
Current code is broken in that the math in calc_load_ve always deals
with unsigned integers values which leads to enormous values of
'nr_active' when ->nr_unint is negative on a tg. The proper way to work
with nr_unint is to always cast it to an signed integer and also make
nr_active a signed values as well to properly deal with negative values.
https://jira.sw.ru/browse/PSBM-143355
Fixes: e303dd8563b5 ("ve/sched/loadavg: Calculate avenrun for Containers
root
cpu cgroups")
Signed-off-by: Nikolay Borisov <nikolay.bori...@virtuozzo.com>
Feature: statistics: loadavg virtualization
---
kernel/sched/loadavg.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index 3910ed5b8323..d6d3b8db8718 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -113,7 +113,7 @@ extern raw_spinlock_t load_ve_lock;
void calc_load_ve(void)
{
- unsigned long nr_unint, nr_active;
+ long nr_unint, nr_active;
struct task_group *tg;
int i;
@@ -133,13 +133,22 @@ void calc_load_ve(void)
* overhead for activate/deactivate operations. So, we
* don't account child cgroup unint tasks here.
*/
- nr_active += tg->cfs_rq[i]->nr_unint;
+ nr_active += (int)tg->cfs_rq[i]->nr_unint;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
nr_active += tg->rt_rq[i]->rt_nr_running;
#endif
}
- nr_active *= FIXED_1;
+ /*
+ * Unless we screwed somewhere, nr_active must always be >= 0,
+ * because we can have no runnable tasks and no tasks in
+ * uninterruptible sleep.
+ */
+ if (WARN_ON_ONCE(nr_active < 0)) {
+ nr_active = 0;
+ } else {
+ nr_active *= FIXED_1;
+ }
tg->avenrun[0] = calc_load(tg->avenrun[0], EXP_1, nr_active);
tg->avenrun[1] = calc_load(tg->avenrun[1], EXP_5, nr_active);
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