[tip: sched/core] sched/fair: Add related data structure for task based throttle

["tip-bot2 for Valentin Schneider" <tip-bot2@linutronix.de>]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     2cd571245b43492867bf1b4252485f3e6647b643
Gitweb:        https://git.kernel.org/tip/2cd571245b43492867bf1b4252485f3e6647b643
Author:        Valentin Schneider <vschneid@redhat.com>
AuthorDate:    Fri, 29 Aug 2025 16:11:16 +08:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 03 Sep 2025 10:03:13 +02:00

sched/fair: Add related data structure for task based throttle

Add related data structures for this new throttle functionality.

Tesed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Link: https://lore.kernel.org/r/20250829081120.806-2-ziqianlu@bytedance.com
---
 include/linux/sched.h |  5 +++++
 kernel/sched/core.c   |  3 +++
 kernel/sched/fair.c   | 13 +++++++++++++
 kernel/sched/sched.h  |  3 +++
 4 files changed, 24 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index f8188b8..644a01b 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -883,6 +883,11 @@ struct task_struct {
 
 #ifdef CONFIG_CGROUP_SCHED
 	struct task_group		*sched_task_group;
+#ifdef CONFIG_CFS_BANDWIDTH
+	struct callback_head		sched_throttle_work;
+	struct list_head		throttle_node;
+	bool				throttled;
+#endif
 #endif
 
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index be00629..feb750a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4490,6 +4490,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
 	p->se.cfs_rq			= NULL;
+#ifdef CONFIG_CFS_BANDWIDTH
+	init_cfs_throttle_work(p);
+#endif
 #endif
 
 #ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b173a05..8fff40f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5748,6 +5748,18 @@ static inline int throttled_lb_pair(struct task_group *tg,
 	       throttled_hierarchy(dest_cfs_rq);
 }
 
+static void throttle_cfs_rq_work(struct callback_head *work)
+{
+}
+
+void init_cfs_throttle_work(struct task_struct *p)
+{
+	init_task_work(&p->sched_throttle_work, throttle_cfs_rq_work);
+	/* Protect against double add, see throttle_cfs_rq() and throttle_cfs_rq_work() */
+	p->sched_throttle_work.next = &p->sched_throttle_work;
+	INIT_LIST_HEAD(&p->throttle_node);
+}
+
 static int tg_unthrottle_up(struct task_group *tg, void *data)
 {
 	struct rq *rq = data;
@@ -6472,6 +6484,7 @@ static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
 	cfs_rq->runtime_enabled = 0;
 	INIT_LIST_HEAD(&cfs_rq->throttled_list);
 	INIT_LIST_HEAD(&cfs_rq->throttled_csd_list);
+	INIT_LIST_HEAD(&cfs_rq->throttled_limbo_list);
 }
 
 void start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index be9745d..a6493d2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -739,6 +739,7 @@ struct cfs_rq {
 	int			throttle_count;
 	struct list_head	throttled_list;
 	struct list_head	throttled_csd_list;
+	struct list_head        throttled_limbo_list;
 #endif /* CONFIG_CFS_BANDWIDTH */
 #endif /* CONFIG_FAIR_GROUP_SCHED */
 };
@@ -2658,6 +2659,8 @@ extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
 
 extern void init_dl_entity(struct sched_dl_entity *dl_se);
 
+extern void init_cfs_throttle_work(struct task_struct *p);
+
 #define BW_SHIFT		20
 #define BW_UNIT			(1 << BW_SHIFT)
 #define RATIO_SHIFT		8