arch/Kconfig | 38 -------------------------------------- arch/arm64/Kconfig | 1 - arch/loongarch/Kconfig | 1 - arch/powerpc/Kconfig | 1 - arch/riscv/Kconfig | 1 - arch/s390/Kconfig | 1 - arch/x86/Kconfig | 1 - kernel/Kconfig.preempt | 8 ++------ kernel/sched/core.c | 10 ---------- 9 files changed, 2 insertions(+), 60 deletions(-)
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 5b9a28eeed37513778ca6b636253aa8dcf39d55f
Gitweb: https://git.kernel.org/tip/5b9a28eeed37513778ca6b636253aa8dcf39d55f
Author: Mark Rutland <mark.rutland@arm.com>
AuthorDate: Mon, 03 Aug 2026 20:17:30 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 02 Sep 2026 09:37:23 +02:00
sched: dynamic: Remove HAVE_PREEMPT_DYNAMIC_{CALL,KEY}
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
Switching model only changes the behaviour of dynamic_preempt_lazy(),
which uses a static key. There are no other static calls or static keys,
and so there's no need for HAVE_PREEMPT_DYNAMIC_CALL or
HAVE_PREEMPT_DYNAMIC_KEY.
The static key used by dynamic_preempt_lazy() is entirely local to
kernel/sched/core.c, and any architecture which selects
ARCH_HAS_PREEMPT_LAZY implements the necessary support. Remove
PREEMPT_DYNAMIC's dependencies on HAVE_PREEMPT_DYNAMIC_CALL and
HAVE_PREEMPT_DYNAMIC_KEY entirely, leaving the dependency on
ARCH_HAS_PREEMPT_LAZY.
For architectures which previously selected HAVE_PREEMPT_DYNAMIC_KEY,
PREEMPT_DYNAMIC will now be selected by default, matching x86. As the
runtime impact is limited to dynamic_preempt_lazy(), this shouldn't be
as concerning as previously (e.g. where calls to {cond,might}_resched()
stubs could introduce a measurable penalty).
As all of this can work without jump labels, JUMP_LABEL is not selected
explicitly. It is obviously preferable to have JUMP_LABEL enabled, but
this is not functionally necessary.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-6-mark.rutland@arm.com
---
arch/Kconfig | 38 --------------------------------------
arch/arm64/Kconfig | 1 -
arch/loongarch/Kconfig | 1 -
arch/powerpc/Kconfig | 1 -
arch/riscv/Kconfig | 1 -
arch/s390/Kconfig | 1 -
arch/x86/Kconfig | 1 -
kernel/Kconfig.preempt | 8 ++------
kernel/sched/core.c | 10 ----------
9 files changed, 2 insertions(+), 60 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 45c6577..c0a6a13 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1712,44 +1712,6 @@ config HAVE_STATIC_CALL_INLINE
depends on HAVE_STATIC_CALL
select OBJTOOL
-config HAVE_PREEMPT_DYNAMIC
- bool
-
-config HAVE_PREEMPT_DYNAMIC_CALL
- bool
- depends on HAVE_STATIC_CALL
- select HAVE_PREEMPT_DYNAMIC
- help
- An architecture should select this if it can handle the preemption
- model being selected at boot time using static calls.
-
- Where an architecture selects HAVE_STATIC_CALL_INLINE, any call to a
- preemption function will be patched directly.
-
- Where an architecture does not select HAVE_STATIC_CALL_INLINE, any
- call to a preemption function will go through a trampoline, and the
- trampoline will be patched.
-
- It is strongly advised to support inline static call to avoid any
- overhead.
-
-config HAVE_PREEMPT_DYNAMIC_KEY
- bool
- depends on HAVE_ARCH_JUMP_LABEL
- select HAVE_PREEMPT_DYNAMIC
- help
- An architecture should select this if it can handle the preemption
- model being selected at boot time using static keys.
-
- Each preemption function will be given an early return based on a
- static key. This should have slightly lower overhead than non-inline
- static calls, as this effectively inlines each trampoline into the
- start of its callee. This may avoid redundant work, and may
- integrate better with CFI schemes.
-
- This will have greater overhead than using inline static calls as
- the call to the preemption function cannot be entirely elided.
-
config ARCH_WANT_LD_ORPHAN_WARN
bool
help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b5a51b0..876ef29 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -217,7 +217,6 @@ config ARM64
select HAVE_PERF_EVENTS_NMI if ARM64_PSEUDO_NMI
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
- select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index a21f51e..9480ccf 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -170,7 +170,6 @@ config LOONGARCH
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
- select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE if UNWINDER_ORC
select HAVE_RETHOOK
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2580e27..143381d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -279,7 +279,6 @@ config PPC
select HAVE_PERF_EVENTS_NMI if PPC64
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
- select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
select HAVE_RETHOOK if KPROBES
select HAVE_REGS_AND_STACK_ACCESS_API
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index f8e26c4..66096a0 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -195,7 +195,6 @@ config RISCV
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
- select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RETHOOK
select HAVE_RSEQ
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 4b51bc6..2682a2b 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -246,7 +246,6 @@ config S390
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
- select HAVE_PREEMPT_DYNAMIC_KEY
select HAVE_REGS_AND_STACK_ACCESS_API
select HAVE_RELIABLE_STACKTRACE
select HAVE_RETHOOK
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 15fd9ec..5a84998 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -297,7 +297,6 @@ config X86
select HAVE_STACK_VALIDATION if HAVE_OBJTOOL
select HAVE_STATIC_CALL
select HAVE_STATIC_CALL_INLINE if HAVE_OBJTOOL
- select HAVE_PREEMPT_DYNAMIC_CALL
select HAVE_RSEQ
select HAVE_RUST if X86_64
select HAVE_SYSCALL_TRACEPOINTS
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 68f3218..985aea6 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -132,11 +132,9 @@ config PREEMPTION
config PREEMPT_DYNAMIC
bool "Preemption behaviour defined on boot"
- depends on HAVE_PREEMPT_DYNAMIC
depends on ARCH_HAS_PREEMPT_LAZY
- select JUMP_LABEL if HAVE_PREEMPT_DYNAMIC_KEY
select PREEMPT_BUILD
- default y if HAVE_PREEMPT_DYNAMIC_CALL
+ default y
help
This option allows to define the preemption model on the kernel
command line parameter and thus override the default preemption
@@ -146,9 +144,7 @@ config PREEMPT_DYNAMIC
provide a pre-built kernel binary to reduce the number of kernel
flavors they offer while still offering different usecases.
- The runtime overhead is negligible with HAVE_STATIC_CALL_INLINE enabled
- but if runtime patching is not available for the specific architecture
- then the potential overhead should be considered.
+ The runtime overhead is negligible.
Interesting if you want the same pre-built kernel should be used for
both Server and Desktop workloads.
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0e9022f..0592320 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7886,16 +7886,6 @@ int sched_dynamic_mode(const char *str)
# define preempt_dynamic_key_enable(f) static_key_enable(&sk_dynamic_##f.key)
# define preempt_dynamic_key_disable(f) static_key_disable(&sk_dynamic_##f.key)
-# if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
-# define preempt_dynamic_enable(f) static_call_update(f, f##_dynamic_enabled)
-# define preempt_dynamic_disable(f) static_call_update(f, f##_dynamic_disabled)
-# elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
-# define preempt_dynamic_enable(f) preempt_dynamic_key_enable(f)
-# define preempt_dynamic_disable(f) preempt_dynamic_key_disable(f)
-# else
-# error "Unsupported PREEMPT_DYNAMIC mechanism"
-# endif
-
static DEFINE_MUTEX(sched_dynamic_mutex);
static void __sched_dynamic_update(int mode)© 2016 - 2026 Red Hat, Inc.