[PATCH 05/17] sched_ext: Relocate cpu_acquire/cpu_release to end of struct sched_ext_ops

[PATCH 05/17] sched_ext: Relocate cpu_acquire/cpu_release to end of struct sched_ext_ops

[Tejun Heo]

cpu_acquire and cpu_release are deprecated and slated for removal. Move
their declarations to the end of struct sched_ext_ops so an upcoming
cid-form struct (sched_ext_ops_cid) can omit them entirely without
disturbing the offsets of the shared fields.

Switch the two SCX_HAS_OP() callers for these ops to direct field checks
since the relocated ops sit outside the SCX_OPI_END range covered by the
has_op bitmap.

scx_kf_allow_flags[] auto-sizes to the highest used SCX_OP_IDX, so
SCX_OP_IDX(cpu_release) moving to a higher index just enlarges the
sparse array; the lookup logic is unchanged.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext.c          |  4 +--
 kernel/sched/ext_internal.h | 54 ++++++++++++++++++++++---------------
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index a94e621d2c6c..ad255268f207 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2814,7 +2814,7 @@ static int balance_one(struct rq *rq, struct task_struct *prev)
 		 * core. This callback complements ->cpu_release(), which is
 		 * emitted in switch_class().
 		 */
-		if (SCX_HAS_OP(sch, cpu_acquire))
+		if (sch->ops.cpu_acquire)
 			SCX_CALL_OP(sch, cpu_acquire, rq, cpu, NULL);
 		rq->scx.cpu_released = false;
 	}
@@ -2960,7 +2960,7 @@ static void switch_class(struct rq *rq, struct task_struct *next)
 	 *  next time that balance_one() is invoked.
 	 */
 	if (!rq->scx.cpu_released) {
-		if (SCX_HAS_OP(sch, cpu_release)) {
+		if (sch->ops.cpu_release) {
 			struct scx_cpu_release_args args = {
 				.reason = preempt_reason_from_class(next_class),
 				.task = next,
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index fb1a555faaaa..dee7f7e2a2ca 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -523,28 +523,6 @@ struct sched_ext_ops {
 	 */
 	void (*update_idle)(s32 cpu, bool idle);
 
-	/**
-	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
-	 * @cpu: The CPU being acquired by the BPF scheduler.
-	 * @args: Acquire arguments, see the struct definition.
-	 *
-	 * A CPU that was previously released from the BPF scheduler is now once
-	 * again under its control.
-	 */
-	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
-
-	/**
-	 * @cpu_release: A CPU is taken away from the BPF scheduler
-	 * @cpu: The CPU being released by the BPF scheduler.
-	 * @args: Release arguments, see the struct definition.
-	 *
-	 * The specified CPU is no longer under the control of the BPF
-	 * scheduler. This could be because it was preempted by a higher
-	 * priority sched_class, though there may be other reasons as well. The
-	 * caller should consult @args->reason to determine the cause.
-	 */
-	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
-
 	/**
 	 * @init_task: Initialize a task to run in a BPF scheduler
 	 * @p: task to initialize for BPF scheduling
@@ -835,6 +813,38 @@ struct sched_ext_ops {
 
 	/* internal use only, must be NULL */
 	void __rcu *priv;
+
+	/*
+	 * Deprecated callbacks. Kept at the end of the struct so the cid-form
+	 * struct (sched_ext_ops_cid) can omit them without affecting the
+	 * shared field offsets. Use SCX_ENQ_IMMED instead. Sitting past
+	 * SCX_OPI_END means has_op doesn't cover them, so SCX_HAS_OP() cannot
+	 * be used; callers must test sch->ops.cpu_acquire / cpu_release
+	 * directly.
+	 */
+
+	/**
+	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
+	 * @cpu: The CPU being acquired by the BPF scheduler.
+	 * @args: Acquire arguments, see the struct definition.
+	 *
+	 * A CPU that was previously released from the BPF scheduler is now once
+	 * again under its control. Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
+
+	/**
+	 * @cpu_release: A CPU is taken away from the BPF scheduler
+	 * @cpu: The CPU being released by the BPF scheduler.
+	 * @args: Release arguments, see the struct definition.
+	 *
+	 * The specified CPU is no longer under the control of the BPF
+	 * scheduler. This could be because it was preempted by a higher
+	 * priority sched_class, though there may be other reasons as well. The
+	 * caller should consult @args->reason to determine the cause.
+	 * Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
 };
 
 enum scx_opi {
-- 
2.53.0

[PATCHSET v2 REPOST sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops

[Tejun Heo]

Hello,

Reposting v2 because the original send was not properly threaded -
each patch went out as a standalone top-level message. Content is
unchanged from the original v2.

Original v2: https://lore.kernel.org/r/20260424013220.2923402-1-tj@kernel.org

v2 of https://lore.kernel.org/r/20260421071945.3110084-1-tj@kernel.org

v2:
- Add ext-types.h first patch for early subsystem-wide type defs.
- cid: publish the cid tables with WRITE_ONCE / read with READ_ONCE;
  document the visibility contract.
- cid-kfuncs: NULL-guard scx_bpf_this_cid / scx_bpf_task_cid for
  TRACING/SYSCALL callers before any SCX sched has enabled.
- cid-struct-ops: use struct_size() for the set_cmask_scratch percpu
  alloc; cluster __scx_is_cid_type disable with __scx_enabled disable
  in scx_root_disable().
- cid-kfunc-filter: sync per-entry kfunc flags with each kfunc's
  primary BTF_ID_FLAGS() declaration (Zhao). pahole intersects flags
  across occurrences; omitting them drops the flags globally - the
  visible symptom was KF_IMPLICIT_ARGS getting cleared on
  scx_bpf_kick_cpu, leaking bpf_prog_aux into vmlinux.h.
- cmask: narrow to the helpers this series actually uses;
  cmask_copy_from_kernel contract and runtime guard.

This patchset introduces topological CPU IDs (cids) - dense,
topology-ordered cpu identifiers - and an alternative cid-form struct_ops
type that lets BPF schedulers operate in cid space directly.

Key pieces:

- cid space: scx_cid_init() walks nodes * LLCs * cores * threads and packs
  a dense cid mapping. The mapping can be overridden via
  scx_bpf_cid_override(). See "Topological CPU IDs" in ext_cid.h for the
  model.

- cmask: a base-windowed bitmap over cid space. Kernel and BPF helpers with
  identical semantics. Used by scx_qmap for per-task affinity and idle-cid
  tracking; meant to be the substrate for sub-sched cid allocation.

- bpf_sched_ext_ops_cid: a parallel struct_ops type whose callbacks take
  cids/cmasks instead of cpus/cpumasks. Kernel translates at the boundary
  via scx_cpu_arg() / scx_cpu_ret(); the two struct types share offsets up
  through @priv (verified by BUILD_BUG_ON) so the union view in scx_sched
  works without function-pointer casts. Sub-sched support is tied to
  cid-form: validate_ops() rejects cpu-form sub-scheds and cpu-form roots
  that expose sub_attach / sub_detach.

- cid-form kfuncs: scx_bpf_kick_cid, scx_bpf_cidperf_{cap,cur,set},
  scx_bpf_cid_curr, scx_bpf_task_cid, scx_bpf_this_cid,
  scx_bpf_nr_{cids,online_cids}, scx_bpf_cid_to_cpu, scx_bpf_cpu_to_cid.
  A cid-form program may not call cpu-only kfuncs (enforced at verifier
  load via scx_kfunc_context_filter); the reverse is intentionally
  permissive to ease migration.

- scx_qmap port: scx_qmap is converted to cid-form. It uses the cmask-based
  idle picker, per-task cid-space cpus_allowed, and cid-form kfuncs
  throughout. Sub-sched dispatching via scx_bpf_sub_dispatch() continues to
  work.

v2 re-tested on the 16-cpu QEMU: cid-form scx_qmap, cpu-form scx_simple,
cid<->cpu cycling, scx_qmap under stress-ng, hotplug auto-restart, and
sub-sched (root scx_qmap + cgroup-scoped scx_qmap child). Clean.

Based on sched_ext/for-7.2 (c2929bc21dce).

 0001-sched_ext-Add-ext_types.h-for-early-subsystem-wide-d.patch
 0002-sched_ext-Rename-ops_cpu_valid-to-scx_cpu_valid-and-.patch
 0003-sched_ext-Move-scx_exit-scx_error-and-friends-to-ext.patch
 0004-sched_ext-Shift-scx_kick_cpu-validity-check-to-scx_b.patch
 0005-sched_ext-Relocate-cpu_acquire-cpu_release-to-end-of.patch
 0006-sched_ext-Make-scx_enable-take-scx_enable_cmd.patch
 0007-sched_ext-Add-topological-CPU-IDs-cids.patch
 0008-sched_ext-Add-scx_bpf_cid_override-kfunc.patch
 0009-tools-sched_ext-Add-struct_size-helpers-to-common.bp.patch
 0010-sched_ext-Add-cmask-a-base-windowed-bitmap-over-cid-.patch
 0011-sched_ext-Add-cid-form-kfunc-wrappers-alongside-cpu-.patch
 0012-sched_ext-Add-bpf_sched_ext_ops_cid-struct_ops-type.patch
 0013-sched_ext-Forbid-cpu-form-kfuncs-from-cid-form-sched.patch
 0014-tools-sched_ext-scx_qmap-Restart-on-hotplug-instead-.patch
 0015-tools-sched_ext-scx_qmap-Add-cmask-based-idle-tracki.patch
 0016-tools-sched_ext-scx_qmap-Port-to-cid-form-struct_ops.patch
 0017-sched_ext-Require-cid-form-struct_ops-for-sub-sched-.patch

Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-cid-v2

 kernel/sched/build_policy.c              |   2 +
 kernel/sched/ext.c                       | 650 +++++++++++++++++++++++++----
 kernel/sched/ext_cid.c                   | 417 ++++++++++++++++++++
 kernel/sched/ext_cid.h                   | 164 ++++++++
 kernel/sched/ext_idle.c                  |   8 +-
 kernel/sched/ext_internal.h              | 203 +++++++---
 kernel/sched/ext_types.h                 | 104 +++++
 tools/sched_ext/include/scx/cid.bpf.h    | 597 ++++++++++++++++++++++++++++
 tools/sched_ext/include/scx/common.bpf.h |  23 ++
 tools/sched_ext/include/scx/compat.bpf.h |  24 ++
 tools/sched_ext/scx_qmap.bpf.c           | 306 ++++++++-------
 tools/sched_ext/scx_qmap.c               |  25 +-
 tools/sched_ext/scx_qmap.h               |   2 +-
 13 files changed, 2240 insertions(+), 285 deletions(-)

--
tejun

[PATCH 05/17] sched_ext: Relocate cpu_acquire/cpu_release to end of struct sched_ext_ops

[Tejun Heo]

cpu_acquire and cpu_release are deprecated and slated for removal. Move
their declarations to the end of struct sched_ext_ops so an upcoming
cid-form struct (sched_ext_ops_cid) can omit them entirely without
disturbing the offsets of the shared fields.

Switch the two SCX_HAS_OP() callers for these ops to direct field checks
since the relocated ops sit outside the SCX_OPI_END range covered by the
has_op bitmap.

scx_kf_allow_flags[] auto-sizes to the highest used SCX_OP_IDX, so
SCX_OP_IDX(cpu_release) moving to a higher index just enlarges the
sparse array; the lookup logic is unchanged.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext.c          |  4 +--
 kernel/sched/ext_internal.h | 54 ++++++++++++++++++++++---------------
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index a94e621d2c6c..ad255268f207 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2814,7 +2814,7 @@ static int balance_one(struct rq *rq, struct task_struct *prev)
 		 * core. This callback complements ->cpu_release(), which is
 		 * emitted in switch_class().
 		 */
-		if (SCX_HAS_OP(sch, cpu_acquire))
+		if (sch->ops.cpu_acquire)
 			SCX_CALL_OP(sch, cpu_acquire, rq, cpu, NULL);
 		rq->scx.cpu_released = false;
 	}
@@ -2960,7 +2960,7 @@ static void switch_class(struct rq *rq, struct task_struct *next)
 	 *  next time that balance_one() is invoked.
 	 */
 	if (!rq->scx.cpu_released) {
-		if (SCX_HAS_OP(sch, cpu_release)) {
+		if (sch->ops.cpu_release) {
 			struct scx_cpu_release_args args = {
 				.reason = preempt_reason_from_class(next_class),
 				.task = next,
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index fb1a555faaaa..dee7f7e2a2ca 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -523,28 +523,6 @@ struct sched_ext_ops {
 	 */
 	void (*update_idle)(s32 cpu, bool idle);
 
-	/**
-	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
-	 * @cpu: The CPU being acquired by the BPF scheduler.
-	 * @args: Acquire arguments, see the struct definition.
-	 *
-	 * A CPU that was previously released from the BPF scheduler is now once
-	 * again under its control.
-	 */
-	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
-
-	/**
-	 * @cpu_release: A CPU is taken away from the BPF scheduler
-	 * @cpu: The CPU being released by the BPF scheduler.
-	 * @args: Release arguments, see the struct definition.
-	 *
-	 * The specified CPU is no longer under the control of the BPF
-	 * scheduler. This could be because it was preempted by a higher
-	 * priority sched_class, though there may be other reasons as well. The
-	 * caller should consult @args->reason to determine the cause.
-	 */
-	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
-
 	/**
 	 * @init_task: Initialize a task to run in a BPF scheduler
 	 * @p: task to initialize for BPF scheduling
@@ -835,6 +813,38 @@ struct sched_ext_ops {
 
 	/* internal use only, must be NULL */
 	void __rcu *priv;
+
+	/*
+	 * Deprecated callbacks. Kept at the end of the struct so the cid-form
+	 * struct (sched_ext_ops_cid) can omit them without affecting the
+	 * shared field offsets. Use SCX_ENQ_IMMED instead. Sitting past
+	 * SCX_OPI_END means has_op doesn't cover them, so SCX_HAS_OP() cannot
+	 * be used; callers must test sch->ops.cpu_acquire / cpu_release
+	 * directly.
+	 */
+
+	/**
+	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
+	 * @cpu: The CPU being acquired by the BPF scheduler.
+	 * @args: Acquire arguments, see the struct definition.
+	 *
+	 * A CPU that was previously released from the BPF scheduler is now once
+	 * again under its control. Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
+
+	/**
+	 * @cpu_release: A CPU is taken away from the BPF scheduler
+	 * @cpu: The CPU being released by the BPF scheduler.
+	 * @args: Release arguments, see the struct definition.
+	 *
+	 * The specified CPU is no longer under the control of the BPF
+	 * scheduler. This could be because it was preempted by a higher
+	 * priority sched_class, though there may be other reasons as well. The
+	 * caller should consult @args->reason to determine the cause.
+	 * Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
 };
 
 enum scx_opi {
-- 
2.53.0

[PATCHSET v3 sched_ext/for-7.2] sched_ext: Topological CPU IDs and cid-form struct_ops

[Tejun Heo]

Hello,

v3 (all from the Sashiko AI review at
https://sashiko.dev/#/patchset/20260424172721.3458520-1-tj%40kernel.org):

- cid: drop leaked cpus_read_lock() on scx_cid_init() failure;
  BUILD_BUG_ON tightened to NR_CPUS<=8192 to match the BPF cmask
  helpers' CMASK_MAX_WORDS coverage.
- bpf-struct-size: use offsetof() in struct_size() to match the
  kernel <linux/overflow.h> macro semantics (no inflation from
  trailing struct padding).
- cmask: cmask_copy_from_kernel() validates src->base==0 via
  probe-read; nr_bits check is bit-level rather than rounded-up
  word-count.
- cid-qmap-idle: qmap_init() refuses to load when scx_bpf_nr_cids()
  exceeds SCX_QMAP_MAX_CPUS; the task_ctx flex array would otherwise
  overflow into the next slab entry.

v2: https://lore.kernel.org/r/20260424172721.3458520-1-tj@kernel.org
v1: https://lore.kernel.org/r/20260421071945.3110084-1-tj@kernel.org

This patchset introduces topological CPU IDs (cids) - dense,
topology-ordered cpu identifiers - and an alternative cid-form struct_ops
type that lets BPF schedulers operate in cid space directly.

Key pieces:

- cid space: scx_cid_init() walks nodes * LLCs * cores * threads and packs
  a dense cid mapping. The mapping can be overridden via
  scx_bpf_cid_override(). See "Topological CPU IDs" in ext_cid.h for the
  model.

- cmask: a base-windowed bitmap over cid space. Kernel and BPF helpers with
  identical semantics. Used by scx_qmap for per-task affinity and idle-cid
  tracking; meant to be the substrate for sub-sched cid allocation.

- bpf_sched_ext_ops_cid: a parallel struct_ops type whose callbacks take
  cids/cmasks instead of cpus/cpumasks. Kernel translates at the boundary
  via scx_cpu_arg() / scx_cpu_ret(); the two struct types share offsets up
  through @priv (verified by BUILD_BUG_ON) so the union view in scx_sched
  works without function-pointer casts. Sub-sched support is tied to
  cid-form: validate_ops() rejects cpu-form sub-scheds and cpu-form roots
  that expose sub_attach / sub_detach.

- cid-form kfuncs: scx_bpf_kick_cid, scx_bpf_cidperf_{cap,cur,set},
  scx_bpf_cid_curr, scx_bpf_task_cid, scx_bpf_this_cid,
  scx_bpf_nr_{cids,online_cids}, scx_bpf_cid_to_cpu, scx_bpf_cpu_to_cid.
  A cid-form program may not call cpu-only kfuncs (enforced at verifier
  load via scx_kfunc_context_filter); the reverse is intentionally
  permissive to ease migration.

- scx_qmap port: scx_qmap is converted to cid-form. It uses the cmask-based
  idle picker, per-task cid-space cpus_allowed, and cid-form kfuncs
  throughout. Sub-sched dispatching via scx_bpf_sub_dispatch() continues to
  work.

v3 re-tested on the 16-cpu QEMU: cid-form scx_qmap under stress-ng plus
reload cycles, hotplug auto-restart, and sub-sched (root scx_qmap +
cgroup-scoped scx_qmap child). Clean.

Based on sched_ext/for-7.2 (4939721aad2e).

 0001-sched_ext-Add-ext_types.h-for-early-subsystem-wide-d.patch
 0002-sched_ext-Rename-ops_cpu_valid-to-scx_cpu_valid-and-.patch
 0003-sched_ext-Move-scx_exit-scx_error-and-friends-to-ext.patch
 0004-sched_ext-Shift-scx_kick_cpu-validity-check-to-scx_b.patch
 0005-sched_ext-Relocate-cpu_acquire-cpu_release-to-end-of.patch
 0006-sched_ext-Make-scx_enable-take-scx_enable_cmd.patch
 0007-sched_ext-Add-topological-CPU-IDs-cids.patch
 0008-sched_ext-Add-scx_bpf_cid_override-kfunc.patch
 0009-tools-sched_ext-Add-struct_size-helpers-to-common.bp.patch
 0010-sched_ext-Add-cmask-a-base-windowed-bitmap-over-cid-.patch
 0011-sched_ext-Add-cid-form-kfunc-wrappers-alongside-cpu-.patch
 0012-sched_ext-Add-bpf_sched_ext_ops_cid-struct_ops-type.patch
 0013-sched_ext-Forbid-cpu-form-kfuncs-from-cid-form-sched.patch
 0014-tools-sched_ext-scx_qmap-Restart-on-hotplug-instead-.patch
 0015-tools-sched_ext-scx_qmap-Add-cmask-based-idle-tracki.patch
 0016-tools-sched_ext-scx_qmap-Port-to-cid-form-struct_ops.patch
 0017-sched_ext-Require-cid-form-struct_ops-for-sub-sched-.patch

Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git scx-cid-v3

 kernel/sched/build_policy.c              |   3 +
 kernel/sched/ext.c                       | 651 ++++++++++++++++++++++++++----
 kernel/sched/ext_cid.c                   | 409 +++++++++++++++++++
 kernel/sched/ext_cid.h                   | 164 ++++++++
 kernel/sched/ext_idle.c                  |   8 +-
 kernel/sched/ext_internal.h              | 205 +++++++---
 kernel/sched/ext_types.h                 | 104 +++++
 tools/sched_ext/include/scx/cid.bpf.h    | 667 +++++++++++++++++++++++++++++++
 tools/sched_ext/include/scx/common.bpf.h |  23 ++
 tools/sched_ext/include/scx/compat.bpf.h |  24 ++
 tools/sched_ext/scx_qmap.bpf.c           | 346 +++++++++-------
 tools/sched_ext/scx_qmap.c               |  70 +++-
 tools/sched_ext/scx_qmap.h               |   2 +-
 13 files changed, 2391 insertions(+), 285 deletions(-)

Thanks.

--
tejun

[PATCH 05/17] sched_ext: Relocate cpu_acquire/cpu_release to end of struct sched_ext_ops

[Tejun Heo]

cpu_acquire and cpu_release are deprecated and slated for removal. Move
their declarations to the end of struct sched_ext_ops so an upcoming
cid-form struct (sched_ext_ops_cid) can omit them entirely without
disturbing the offsets of the shared fields.

Switch the two SCX_HAS_OP() callers for these ops to direct field checks
since the relocated ops sit outside the SCX_OPI_END range covered by the
has_op bitmap.

scx_kf_allow_flags[] auto-sizes to the highest used SCX_OP_IDX, so
SCX_OP_IDX(cpu_release) moving to a higher index just enlarges the
sparse array; the lookup logic is unchanged.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
---
 kernel/sched/ext.c          |  4 +--
 kernel/sched/ext_internal.h | 54 ++++++++++++++++++++++---------------
 2 files changed, 34 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index e9cf9d8f4626..b197da2b960d 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -2823,7 +2823,7 @@ static int balance_one(struct rq *rq, struct task_struct *prev)
 		 * core. This callback complements ->cpu_release(), which is
 		 * emitted in switch_class().
 		 */
-		if (SCX_HAS_OP(sch, cpu_acquire))
+		if (sch->ops.cpu_acquire)
 			SCX_CALL_OP(sch, cpu_acquire, rq, cpu, NULL);
 		rq->scx.cpu_released = false;
 	}
@@ -2969,7 +2969,7 @@ static void switch_class(struct rq *rq, struct task_struct *next)
 	 *  next time that balance_one() is invoked.
 	 */
 	if (!rq->scx.cpu_released) {
-		if (SCX_HAS_OP(sch, cpu_release)) {
+		if (sch->ops.cpu_release) {
 			struct scx_cpu_release_args args = {
 				.reason = preempt_reason_from_class(next_class),
 				.task = next,
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index d4960df23da4..919d4aa08656 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -523,28 +523,6 @@ struct sched_ext_ops {
 	 */
 	void (*update_idle)(s32 cpu, bool idle);
 
-	/**
-	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
-	 * @cpu: The CPU being acquired by the BPF scheduler.
-	 * @args: Acquire arguments, see the struct definition.
-	 *
-	 * A CPU that was previously released from the BPF scheduler is now once
-	 * again under its control.
-	 */
-	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
-
-	/**
-	 * @cpu_release: A CPU is taken away from the BPF scheduler
-	 * @cpu: The CPU being released by the BPF scheduler.
-	 * @args: Release arguments, see the struct definition.
-	 *
-	 * The specified CPU is no longer under the control of the BPF
-	 * scheduler. This could be because it was preempted by a higher
-	 * priority sched_class, though there may be other reasons as well. The
-	 * caller should consult @args->reason to determine the cause.
-	 */
-	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
-
 	/**
 	 * @init_task: Initialize a task to run in a BPF scheduler
 	 * @p: task to initialize for BPF scheduling
@@ -835,6 +813,38 @@ struct sched_ext_ops {
 
 	/* internal use only, must be NULL */
 	void __rcu *priv;
+
+	/*
+	 * Deprecated callbacks. Kept at the end of the struct so the cid-form
+	 * struct (sched_ext_ops_cid) can omit them without affecting the
+	 * shared field offsets. Use SCX_ENQ_IMMED instead. Sitting past
+	 * SCX_OPI_END means has_op doesn't cover them, so SCX_HAS_OP() cannot
+	 * be used; callers must test sch->ops.cpu_acquire / cpu_release
+	 * directly.
+	 */
+
+	/**
+	 * @cpu_acquire: A CPU is becoming available to the BPF scheduler
+	 * @cpu: The CPU being acquired by the BPF scheduler.
+	 * @args: Acquire arguments, see the struct definition.
+	 *
+	 * A CPU that was previously released from the BPF scheduler is now once
+	 * again under its control. Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_acquire)(s32 cpu, struct scx_cpu_acquire_args *args);
+
+	/**
+	 * @cpu_release: A CPU is taken away from the BPF scheduler
+	 * @cpu: The CPU being released by the BPF scheduler.
+	 * @args: Release arguments, see the struct definition.
+	 *
+	 * The specified CPU is no longer under the control of the BPF
+	 * scheduler. This could be because it was preempted by a higher
+	 * priority sched_class, though there may be other reasons as well. The
+	 * caller should consult @args->reason to determine the cause.
+	 * Deprecated; use SCX_ENQ_IMMED instead.
+	 */
+	void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
 };
 
 enum scx_opi {
-- 
2.54.0