[tip: sched/urgent] sched/eevdf: Fix rb augmented with multi fields

[tip-bot2 for Vincent Guittot]

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

Commit-ID:     51b0e68cfa0ac69e3c3ea9d6753af7e15dfaab22
Gitweb:        https://git.kernel.org/tip/51b0e68cfa0ac69e3c3ea9d6753af7e15dfaab22
Author:        Vincent Guittot <vincent.guittot@xxxxxxxxxx>
AuthorDate:    Wed, 09 Sep 2026 17:05:22 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 10 Sep 2026 10:22:52 +02:00

sched/eevdf: Fix rb augmented with multi fields

The eevdf rb tree maintains 3 augmented fields but only one is currently
copied when balancing the tree.

Add a more generic define that can be used when there are several augmented
fields. In this case, we provide a function that takes care of copying all
fields.

Fixes: aef6987d8954 ("sched/eevdf: Propagate min_slice up the cgroup hierarchy")
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Tested-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Link: https://patch.msgid.link/20260909150522.858312-1-vincent.guittot@xxxxxxxxxx
---
 include/linux/rbtree_augmented.h | 35 ++++++++++++++++++++++++-------
 kernel/sched/fair.c              | 12 +++++++++--
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/include/linux/rbtree_augmented.h b/include/linux/rbtree_augmented.h
index 6dbc5a1..d2fa1c4 100644
--- a/include/linux/rbtree_augmented.h
+++ b/include/linux/rbtree_augmented.h
@@ -87,18 +87,18 @@ rb_add_augmented_cached(struct rb_node *node, struct rb_root_cached *tree,
 }
 
 /*
- * Template for declaring augmented rbtree callbacks (generic case)
+ * Template for declaring augmented rbtree callbacks (generic multi fields)
  *
  * RBSTATIC:    'static' or empty
  * RBNAME:      name of the rb_augment_callbacks structure
  * RBSTRUCT:    struct type of the tree nodes
  * RBFIELD:     name of struct rb_node field within RBSTRUCT
- * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
- * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED data
+ * RBCOPY:	name of function that copies the RBAUGMENTED datas
+ * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED datas
  */
 
-#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,				\
-			     RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE)	\
+#define RB_DECLARE_CALLBACKS_MULTI(RBSTATIC, RBNAME,			\
+			     RBSTRUCT, RBFIELD, RBCOPY, RBCOMPUTE)	\
 static inline void							\
 RBNAME ## _propagate(struct rb_node *rb, struct rb_node *stop)		\
 {									\
@@ -114,14 +114,14 @@ RBNAME ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)		\
 {									\
 	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD);		\
 	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD);		\
-	new->RBAUGMENTED = old->RBAUGMENTED;				\
+	RBCOPY(new, old);						\
 }									\
 static void								\
 RBNAME ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)	\
 {									\
 	RBSTRUCT *old = rb_entry(rb_old, RBSTRUCT, RBFIELD);		\
 	RBSTRUCT *new = rb_entry(rb_new, RBSTRUCT, RBFIELD);		\
-	new->RBAUGMENTED = old->RBAUGMENTED;				\
+	RBCOPY(new, old);						\
 	RBCOMPUTE(old, false);						\
 }									\
 RBSTATIC const struct rb_augment_callbacks RBNAME = {			\
@@ -131,6 +131,27 @@ RBSTATIC const struct rb_augment_callbacks RBNAME = {			\
 };
 
 /*
+ * Template for declaring augmented rbtree callbacks (generic single field)
+ *
+ * RBSTATIC:    'static' or empty
+ * RBNAME:      name of the rb_augment_callbacks structure
+ * RBSTRUCT:    struct type of the tree nodes
+ * RBFIELD:     name of struct rb_node field within RBSTRUCT
+ * RBAUGMENTED: name of field within RBSTRUCT holding data for subtree
+ * RBCOMPUTE:   name of function that recomputes the RBAUGMENTED data
+ */
+
+#define RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME,				\
+			     RBSTRUCT, RBFIELD, RBAUGMENTED, RBCOMPUTE)	\
+static inline void							\
+RBNAME ## _copy_single(RBSTRUCT *new, RBSTRUCT *old)			\
+{									\
+	new->RBAUGMENTED = old->RBAUGMENTED;				\
+}									\
+RB_DECLARE_CALLBACKS_MULTI(RBSTATIC, RBNAME,				\
+		     RBSTRUCT, RBFIELD, RBNAME ## _copy_single, RBCOMPUTE)
+
+/*
  * Template for declaring augmented rbtree callbacks,
  * computing RBAUGMENTED scalar as max(RBCOMPUTE(node)) for all subtree nodes.
  *
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 5b944f9..944833e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1032,6 +1032,13 @@ static inline void __max_slice_update(struct sched_entity *se, struct rb_node *n
 	}
 }
 
+static inline void min_vruntime_copy(struct sched_entity *new, struct sched_entity *old)
+{
+	new->min_vruntime = old->min_vruntime;
+	new->min_slice = old->min_slice;
+	new->max_slice = old->max_slice;
+}
+
 /*
  * se->min_vruntime = min(se->vruntime, {left,right}->min_vruntime)
  */
@@ -1059,8 +1066,9 @@ static inline bool min_vruntime_update(struct sched_entity *se, bool exit)
 	       se->max_slice == old_max_slice;
 }
 
-RB_DECLARE_CALLBACKS(static, min_vruntime_cb, struct sched_entity,
-		     run_node, min_vruntime, min_vruntime_update);
+
+RB_DECLARE_CALLBACKS_MULTI(static, min_vruntime_cb, struct sched_entity,
+		     run_node, min_vruntime_copy, min_vruntime_update);
 
 /*
  * Enqueue an entity into the rb-tree: