[tip:sched/core] sched/fair: Use rq_lock/unlock in online_fair_sched_group

From: tip-bot for Phil Auld
Date: Mon Aug 12 2019 - 08:52:29 EST


Commit-ID: a46d14eca7b75fffe35603aa8b81df654353d80f
Gitweb: https://git.kernel.org/tip/a46d14eca7b75fffe35603aa8b81df654353d80f
Author: Phil Auld <pauld@xxxxxxxxxx>
AuthorDate: Thu, 1 Aug 2019 09:37:49 -0400
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 12 Aug 2019 14:45:34 +0200

sched/fair: Use rq_lock/unlock in online_fair_sched_group

Enabling WARN_DOUBLE_CLOCK in /sys/kernel/debug/sched_features causes
warning to fire in update_rq_clock. This seems to be caused by onlining
a new fair sched group not using the rq lock wrappers.

[] rq->clock_update_flags & RQCF_UPDATED
[] WARNING: CPU: 5 PID: 54385 at kernel/sched/core.c:210 update_rq_clock+0xec/0x150

[] Call Trace:
[] online_fair_sched_group+0x53/0x100
[] cpu_cgroup_css_online+0x16/0x20
[] online_css+0x1c/0x60
[] cgroup_apply_control_enable+0x231/0x3b0
[] cgroup_mkdir+0x41b/0x530
[] kernfs_iop_mkdir+0x61/0xa0
[] vfs_mkdir+0x108/0x1a0
[] do_mkdirat+0x77/0xe0
[] do_syscall_64+0x55/0x1d0
[] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Using the wrappers in online_fair_sched_group instead of the raw locking
removes this warning.

[ tglx: Use rq_*lock_irq() ]

Signed-off-by: Phil Auld <pauld@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190801133749.11033-1-pauld@xxxxxxxxxx
---
kernel/sched/fair.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 19c58599e967..1054d2cf6aaa 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10281,18 +10281,18 @@ err:
void online_fair_sched_group(struct task_group *tg)
{
struct sched_entity *se;
+ struct rq_flags rf;
struct rq *rq;
int i;

for_each_possible_cpu(i) {
rq = cpu_rq(i);
se = tg->se[i];
-
- raw_spin_lock_irq(&rq->lock);
+ rq_lock_irq(rq, &rf);
update_rq_clock(rq);
attach_entity_cfs_rq(se);
sync_throttle(tg, i);
- raw_spin_unlock_irq(&rq->lock);
+ rq_unlock_irq(rq, &rf);
}
}