[PATCH v3 7/7] mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE

Qi Zheng
2025-12-17T09:47:31Z

From: Qi Zheng <zhengqi.arch@bytedance.com>

The PT_RECLAIM can work on all architectures that support
MMU_GATHER_RCU_TABLE_FREE, so make PT_RECLAIM depends on
MMU_GATHER_RCU_TABLE_FREE.

BTW, change PT_RECLAIM to be enabled by default, since nobody should want
to turn it off.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
arch/x86/Kconfig | 1 -
mm/Kconfig | 9 ++-------
2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 80527299f859a..0d22da56a71b0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -331,7 +331,6 @@ config X86
select FUNCTION_ALIGNMENT_4B
imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI
select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
- select ARCH_SUPPORTS_PT_RECLAIM if X86_64
select ARCH_SUPPORTS_SCHED_SMT if SMP
select SCHED_SMT if SMP
select ARCH_SUPPORTS_SCHED_CLUSTER if SMP
diff --git a/mm/Kconfig b/mm/Kconfig
index bd0ea5454af82..fc00b429b7129 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1447,14 +1447,9 @@ config ARCH_HAS_USER_SHADOW_STACK
The architecture has hardware support for userspace shadow call
stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss).

-config ARCH_SUPPORTS_PT_RECLAIM
- def_bool n
-
config PT_RECLAIM
- bool "reclaim empty user page table pages"
- default y
- depends on ARCH_SUPPORTS_PT_RECLAIM && MMU && SMP
- select MMU_GATHER_RCU_TABLE_FREE
+ def_bool y
+ depends on MMU_GATHER_RCU_TABLE_FREE
help
Try to reclaim empty user page table pages in paths other than munmap
and exit_mmap path.
--
2.20.1