[PATCH 1/5] sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag

[PATCH 1/5] sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag

[zhidao su]

From: Su Zhidao <suzhidao@xiaomi.com>

SCX_OPS_HAS_CGROUP_WEIGHT was deprecated in 6.15 with a comment
'will be removed on 6.18'. Now that we are at 6.18, remove it.

The flag was a no-op and only triggered a pr_warn() on use. Remove
the flag definition, the warning, and update scx_flatcg which was
the last in-tree user.

Signed-off-by: Su Zhidao <suzhidao@xiaomi.com>
---
 kernel/sched/ext.c                              | 3 ---
 kernel/sched/ext_internal.h                     | 8 +-------
 tools/sched_ext/include/scx/enum_defs.autogen.h | 1 -
 tools/sched_ext/scx_flatcg.bpf.c                | 2 +-
 4 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index c4ccd685259f..56ff5874af94 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -5061,9 +5061,6 @@ static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops)
 		return -EINVAL;
 	}
 
-	if (ops->flags & SCX_OPS_HAS_CGROUP_WEIGHT)
-		pr_warn("SCX_OPS_HAS_CGROUP_WEIGHT is deprecated and a noop\n");
-
 	if (ops->cpu_acquire || ops->cpu_release)
 		pr_warn("ops->cpu_acquire/release() are deprecated, use sched_switch TP instead\n");
 
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index bd26811fea99..3c86c53e1975 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -174,19 +174,13 @@ enum scx_ops_flags {
 	 */
 	SCX_OPS_BUILTIN_IDLE_PER_NODE	= 1LLU << 6,
 
-	/*
-	 * CPU cgroup support flags
-	 */
-	SCX_OPS_HAS_CGROUP_WEIGHT	= 1LLU << 16,	/* DEPRECATED, will be removed on 6.18 */
-
 	SCX_OPS_ALL_FLAGS		= SCX_OPS_KEEP_BUILTIN_IDLE |
 					  SCX_OPS_ENQ_LAST |
 					  SCX_OPS_ENQ_EXITING |
 					  SCX_OPS_ENQ_MIGRATION_DISABLED |
 					  SCX_OPS_ALLOW_QUEUED_WAKEUP |
 					  SCX_OPS_SWITCH_PARTIAL |
-					  SCX_OPS_BUILTIN_IDLE_PER_NODE |
-					  SCX_OPS_HAS_CGROUP_WEIGHT,
+					  SCX_OPS_BUILTIN_IDLE_PER_NODE,
 
 	/* high 8 bits are internal, don't include in SCX_OPS_ALL_FLAGS */
 	__SCX_OPS_INTERNAL_MASK		= 0xffLLU << 56,
diff --git a/tools/sched_ext/include/scx/enum_defs.autogen.h b/tools/sched_ext/include/scx/enum_defs.autogen.h
index dcc945304760..80c885f781ba 100644
--- a/tools/sched_ext/include/scx/enum_defs.autogen.h
+++ b/tools/sched_ext/include/scx/enum_defs.autogen.h
@@ -91,7 +91,6 @@
 #define HAVE_SCX_OPS_SWITCH_PARTIAL
 #define HAVE_SCX_OPS_ENQ_MIGRATION_DISABLED
 #define HAVE_SCX_OPS_ALLOW_QUEUED_WAKEUP
-#define HAVE_SCX_OPS_HAS_CGROUP_WEIGHT
 #define HAVE_SCX_OPS_ALL_FLAGS
 #define HAVE_SCX_OPSS_NONE
 #define HAVE_SCX_OPSS_QUEUEING
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 0e785cff0f24..a8a9234bb41e 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -960,5 +960,5 @@ SCX_OPS_DEFINE(flatcg_ops,
 	       .cgroup_move		= (void *)fcg_cgroup_move,
 	       .init			= (void *)fcg_init,
 	       .exit			= (void *)fcg_exit,
-	       .flags			= SCX_OPS_HAS_CGROUP_WEIGHT | SCX_OPS_ENQ_EXITING,
+	       .flags			= SCX_OPS_ENQ_EXITING,
 	       .name			= "flatcg");
-- 
2.43.0

Re: [PATCH 1/5] sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag

[Andrea Righi]

Hi,

On Fri, Mar 06, 2026 at 08:48:57PM +0800, zhidao su wrote:
> From: Su Zhidao <suzhidao@xiaomi.com>
> 
> SCX_OPS_HAS_CGROUP_WEIGHT was deprecated in 6.15 with a comment
> 'will be removed on 6.18'. Now that we are at 6.18, remove it.
> 
> The flag was a no-op and only triggered a pr_warn() on use. Remove
> the flag definition, the warning, and update scx_flatcg which was
> the last in-tree user.
> 
> Signed-off-by: Su Zhidao <suzhidao@xiaomi.com>

Please, when sending multiple patches, group them together in the same
email thread with cover letter email, otherwise it's very unpractical to
apply and review them.

See Documentation/process/submitting-patches.rst.

Thanks,
-Andrea

> ---
>  kernel/sched/ext.c                              | 3 ---
>  kernel/sched/ext_internal.h                     | 8 +-------
>  tools/sched_ext/include/scx/enum_defs.autogen.h | 1 -
>  tools/sched_ext/scx_flatcg.bpf.c                | 2 +-
>  4 files changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index c4ccd685259f..56ff5874af94 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -5061,9 +5061,6 @@ static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops)
>  		return -EINVAL;
>  	}
>  
> -	if (ops->flags & SCX_OPS_HAS_CGROUP_WEIGHT)
> -		pr_warn("SCX_OPS_HAS_CGROUP_WEIGHT is deprecated and a noop\n");
> -
>  	if (ops->cpu_acquire || ops->cpu_release)
>  		pr_warn("ops->cpu_acquire/release() are deprecated, use sched_switch TP instead\n");
>  
> diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
> index bd26811fea99..3c86c53e1975 100644
> --- a/kernel/sched/ext_internal.h
> +++ b/kernel/sched/ext_internal.h
> @@ -174,19 +174,13 @@ enum scx_ops_flags {
>  	 */
>  	SCX_OPS_BUILTIN_IDLE_PER_NODE	= 1LLU << 6,
>  
> -	/*
> -	 * CPU cgroup support flags
> -	 */
> -	SCX_OPS_HAS_CGROUP_WEIGHT	= 1LLU << 16,	/* DEPRECATED, will be removed on 6.18 */
> -
>  	SCX_OPS_ALL_FLAGS		= SCX_OPS_KEEP_BUILTIN_IDLE |
>  					  SCX_OPS_ENQ_LAST |
>  					  SCX_OPS_ENQ_EXITING |
>  					  SCX_OPS_ENQ_MIGRATION_DISABLED |
>  					  SCX_OPS_ALLOW_QUEUED_WAKEUP |
>  					  SCX_OPS_SWITCH_PARTIAL |
> -					  SCX_OPS_BUILTIN_IDLE_PER_NODE |
> -					  SCX_OPS_HAS_CGROUP_WEIGHT,
> +					  SCX_OPS_BUILTIN_IDLE_PER_NODE,
>  
>  	/* high 8 bits are internal, don't include in SCX_OPS_ALL_FLAGS */
>  	__SCX_OPS_INTERNAL_MASK		= 0xffLLU << 56,
> diff --git a/tools/sched_ext/include/scx/enum_defs.autogen.h b/tools/sched_ext/include/scx/enum_defs.autogen.h
> index dcc945304760..80c885f781ba 100644
> --- a/tools/sched_ext/include/scx/enum_defs.autogen.h
> +++ b/tools/sched_ext/include/scx/enum_defs.autogen.h
> @@ -91,7 +91,6 @@
>  #define HAVE_SCX_OPS_SWITCH_PARTIAL
>  #define HAVE_SCX_OPS_ENQ_MIGRATION_DISABLED
>  #define HAVE_SCX_OPS_ALLOW_QUEUED_WAKEUP
> -#define HAVE_SCX_OPS_HAS_CGROUP_WEIGHT
>  #define HAVE_SCX_OPS_ALL_FLAGS
>  #define HAVE_SCX_OPSS_NONE
>  #define HAVE_SCX_OPSS_QUEUEING
> diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
> index 0e785cff0f24..a8a9234bb41e 100644
> --- a/tools/sched_ext/scx_flatcg.bpf.c
> +++ b/tools/sched_ext/scx_flatcg.bpf.c
> @@ -960,5 +960,5 @@ SCX_OPS_DEFINE(flatcg_ops,
>  	       .cgroup_move		= (void *)fcg_cgroup_move,
>  	       .init			= (void *)fcg_init,
>  	       .exit			= (void *)fcg_exit,
> -	       .flags			= SCX_OPS_HAS_CGROUP_WEIGHT | SCX_OPS_ENQ_EXITING,
> +	       .flags			= SCX_OPS_ENQ_EXITING,
>  	       .name			= "flatcg");
> -- 
> 2.43.0
> 

Re: [PATCH 1/5] sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag

[zhidao su]

From: Su Zhidao <suzhidao@xiaomi.com>

On Fri, Mar 06, 2026 at 03:01:49PM +0100, Andrea Righi wrote:
> Please, when sending multiple patches, group them together in the same
> email thread with cover letter email, otherwise it's very unpractical to
> apply and review them.
>
> See Documentation/process/submitting-patches.rst.

Thanks for the feedback. Apologies for the inconvenience.

I resent the series as a proper patch thread with cover letter:

  Subject: [PATCH 0/5] sched_ext: bypass state machine cleanup and selftest
  Message-ID: <20260306140325.2710927-1-suzhidao@xiaomi.com>

Sorry for the noise.

-- 
Su Zhidao

[PATCH 0/5] sched_ext: bypass state machine cleanup and selftest

[zhidao su]

From: Su Zhidao <suzhidao@xiaomi.com>

This series does a small cleanup pass on the sched_ext bypass code path
and adds a selftest for the bypass mechanism.

Patch 1 removes SCX_OPS_HAS_CGROUP_WEIGHT, which was marked deprecated
in 6.15 with a "will be removed on 6.18" comment. We are now past that
point.

Patches 2-3 improve the bypass code in ext.c: add inline comments
explaining the bypass depth counter semantics and the dequeue/enqueue
re-queue loop, and replace rcu_dereference_all() with the more precise
rcu_dereference_bh() in scx_bypass_lb_timerfn() which runs in softirq
context.

Patch 4 adds a selftest that verifies forward progress under bypass
mode: worker processes are spawned while the scheduler is active, then
bpf_link__destroy() is called (triggering bypass), and the test confirms
all workers complete successfully.

Patch 5 adds a comment to the scx_bypass_depth declaration noting its
planned migration into struct scx_sched.

Tested on 6.18.7 with CONFIG_SCHED_CLASS_EXT=y; all existing selftests
pass.

Su Zhidao (5):
  sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag
  sched_ext: Add comments to scx_bypass() for bypass depth semantics
  sched_ext: Use rcu_dereference_bh() in scx_bypass_lb_timerfn()
  sched_ext/selftests: Add bypass mode operational test
  sched_ext: Document scx_bypass_depth migration path

 kernel/sched/ext.c                            |  29 ++++-
 kernel/sched/ext_internal.h                   |   8 +-
 .../sched_ext/include/scx/enum_defs.autogen.h |   1 -
 tools/sched_ext/scx_flatcg.bpf.c              |   2 +-
 tools/testing/selftests/sched_ext/Makefile    |   1 +
 .../testing/selftests/sched_ext/bypass.bpf.c  |  32 ++++++
 tools/testing/selftests/sched_ext/bypass.c    | 105 ++++++++++++++++++
 7 files changed, 165 insertions(+), 13 deletions(-)
 create mode 100644 tools/testing/selftests/sched_ext/bypass.bpf.c
 create mode 100644 tools/testing/selftests/sched_ext/bypass.c

-- 
2.43.0

[PATCH 1/5] sched_ext: Remove deprecated SCX_OPS_HAS_CGROUP_WEIGHT flag

[zhidao su]

From: Su Zhidao <suzhidao@xiaomi.com>

SCX_OPS_HAS_CGROUP_WEIGHT was deprecated in 6.15 with a comment
'will be removed on 6.18'. Now that we are at 6.18, remove it.

The flag was a no-op and only triggered a pr_warn() on use. Remove
the flag definition, the warning, and update scx_flatcg which was
the last in-tree user.

Signed-off-by: Su Zhidao <suzhidao@xiaomi.com>
---
 kernel/sched/ext.c                              | 3 ---
 kernel/sched/ext_internal.h                     | 8 +-------
 tools/sched_ext/include/scx/enum_defs.autogen.h | 1 -
 tools/sched_ext/scx_flatcg.bpf.c                | 2 +-
 4 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index c4ccd685259f..56ff5874af94 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -5061,9 +5061,6 @@ static int validate_ops(struct scx_sched *sch, const struct sched_ext_ops *ops)
 		return -EINVAL;
 	}
 
-	if (ops->flags & SCX_OPS_HAS_CGROUP_WEIGHT)
-		pr_warn("SCX_OPS_HAS_CGROUP_WEIGHT is deprecated and a noop\n");
-
 	if (ops->cpu_acquire || ops->cpu_release)
 		pr_warn("ops->cpu_acquire/release() are deprecated, use sched_switch TP instead\n");
 
diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
index bd26811fea99..3c86c53e1975 100644
--- a/kernel/sched/ext_internal.h
+++ b/kernel/sched/ext_internal.h
@@ -174,19 +174,13 @@ enum scx_ops_flags {
 	 */
 	SCX_OPS_BUILTIN_IDLE_PER_NODE	= 1LLU << 6,
 
-	/*
-	 * CPU cgroup support flags
-	 */
-	SCX_OPS_HAS_CGROUP_WEIGHT	= 1LLU << 16,	/* DEPRECATED, will be removed on 6.18 */
-
 	SCX_OPS_ALL_FLAGS		= SCX_OPS_KEEP_BUILTIN_IDLE |
 					  SCX_OPS_ENQ_LAST |
 					  SCX_OPS_ENQ_EXITING |
 					  SCX_OPS_ENQ_MIGRATION_DISABLED |
 					  SCX_OPS_ALLOW_QUEUED_WAKEUP |
 					  SCX_OPS_SWITCH_PARTIAL |
-					  SCX_OPS_BUILTIN_IDLE_PER_NODE |
-					  SCX_OPS_HAS_CGROUP_WEIGHT,
+					  SCX_OPS_BUILTIN_IDLE_PER_NODE,
 
 	/* high 8 bits are internal, don't include in SCX_OPS_ALL_FLAGS */
 	__SCX_OPS_INTERNAL_MASK		= 0xffLLU << 56,
diff --git a/tools/sched_ext/include/scx/enum_defs.autogen.h b/tools/sched_ext/include/scx/enum_defs.autogen.h
index dcc945304760..80c885f781ba 100644
--- a/tools/sched_ext/include/scx/enum_defs.autogen.h
+++ b/tools/sched_ext/include/scx/enum_defs.autogen.h
@@ -91,7 +91,6 @@
 #define HAVE_SCX_OPS_SWITCH_PARTIAL
 #define HAVE_SCX_OPS_ENQ_MIGRATION_DISABLED
 #define HAVE_SCX_OPS_ALLOW_QUEUED_WAKEUP
-#define HAVE_SCX_OPS_HAS_CGROUP_WEIGHT
 #define HAVE_SCX_OPS_ALL_FLAGS
 #define HAVE_SCX_OPSS_NONE
 #define HAVE_SCX_OPSS_QUEUEING
diff --git a/tools/sched_ext/scx_flatcg.bpf.c b/tools/sched_ext/scx_flatcg.bpf.c
index 0e785cff0f24..a8a9234bb41e 100644
--- a/tools/sched_ext/scx_flatcg.bpf.c
+++ b/tools/sched_ext/scx_flatcg.bpf.c
@@ -960,5 +960,5 @@ SCX_OPS_DEFINE(flatcg_ops,
 	       .cgroup_move		= (void *)fcg_cgroup_move,
 	       .init			= (void *)fcg_init,
 	       .exit			= (void *)fcg_exit,
-	       .flags			= SCX_OPS_HAS_CGROUP_WEIGHT | SCX_OPS_ENQ_EXITING,
+	       .flags			= SCX_OPS_ENQ_EXITING,
 	       .name			= "flatcg");
-- 
2.43.0