[PATCH v5 15/15] mm/kasan: clean up unneeded ARCH_DEFER_KASAN and kasan_arch_is_ready

Baoquan He
2026-02-25T08:17:38Z

Since commit 1e338f4d99e6 ("kasan: introduce ARCH_DEFER_KASAN and unify
static key across modes"), kasan_arch_is_ready() has been dead code.
And up to now, ARCH_DEFER_KASAN is useless too because of code change
for 'kasan=on|off'.

Here clean them up.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
arch/loongarch/Kconfig | 1 -
arch/powerpc/Kconfig | 1 -
arch/um/Kconfig | 1 -
lib/Kconfig.kasan | 12 ------------
mm/kasan/kasan.h | 6 ------
5 files changed, 21 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index d211c6572b0a..4b7802d02911 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -9,7 +9,6 @@ config LOONGARCH
select ACPI_PPTT if ACPI
select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
select ARCH_BINFMT_ELF_STATE
- select ARCH_NEEDS_DEFER_KASAN
select ARCH_DISABLE_KASAN_INLINE
select ARCH_ENABLE_MEMORY_HOTPLUG
select ARCH_ENABLE_MEMORY_HOTREMOVE
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ad7a2fe63a2a..b51fbc25bdc9 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -122,7 +122,6 @@ config PPC
# Please keep this list sorted alphabetically.
#
select ARCH_32BIT_OFF_T if PPC32
- select ARCH_NEEDS_DEFER_KASAN if PPC_RADIX_MMU
select ARCH_DISABLE_KASAN_INLINE if PPC_RADIX_MMU
select ARCH_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE
select ARCH_ENABLE_MEMORY_HOTPLUG
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 098cda44db22..fd0bedd2c696 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -6,7 +6,6 @@ config UML
bool
default y
select ARCH_DISABLE_KASAN_INLINE if STATIC_LINK
- select ARCH_NEEDS_DEFER_KASAN if STATIC_LINK
select ARCH_WANTS_DYNAMIC_TASK_STRUCT
select ARCH_HAS_CACHE_LINE_SIZE
select ARCH_HAS_CPU_FINALIZE_INIT
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index a4bb610a7a6f..f82889a830fa 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -19,18 +19,6 @@ config ARCH_DISABLE_KASAN_INLINE
Disables both inline and stack instrumentation. Selected by
architectures that do not support these instrumentation types.

-config ARCH_NEEDS_DEFER_KASAN
- bool
-
-config ARCH_DEFER_KASAN
- def_bool y
- depends on KASAN && ARCH_NEEDS_DEFER_KASAN
- help
- Architectures should select this if they need to defer KASAN
- initialization until shadow memory is properly set up. This
- enables runtime control via static keys. Otherwise, KASAN uses
- compile-time constants for better performance.
-
config CC_HAS_KASAN_GENERIC
def_bool $(cc-option, -fsanitize=kernel-address)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index fc9169a54766..f08f7f75c285 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -552,12 +552,6 @@ static inline void kasan_poison_last_granule(const void *address, size_t size) {

#endif /* CONFIG_KASAN_GENERIC */

-#ifndef kasan_arch_is_ready
-static inline bool kasan_arch_is_ready(void) { return true; }
-#elif !defined(CONFIG_KASAN_GENERIC) || !defined(CONFIG_KASAN_OUTLINE)
-#error kasan_arch_is_ready only works in KASAN generic outline mode!
-#endif
-
#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)

void kasan_kunit_test_suite_start(void);