linux-kernel - [PATCH 7/7] mm: make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE

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Message-ID: <0a4d1e6f0bf299cafd1fc624f965bd1ca542cea8.1763117269.git.zhengqi.arch@bytedance.com>
Date: Fri, 14 Nov 2025 19:11:21 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: will@...nel.org,
	aneesh.kumar@...nel.org,
	npiggin@...il.com,
	peterz@...radead.org,
	dev.jain@....com,
	akpm@...ux-foundation.org,
	david@...hat.com,
	ioworker0@...il.com
Cc: linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-alpha@...r.kernel.org,
	linux-snps-arc@...ts.infradead.org,
	loongarch@...ts.linux.dev,
	linux-mips@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linux-um@...ts.infradead.org,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH 7/7] mm: make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE_FREE && 64BIT

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

Make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE_FREE so that PT_RECLAIM can
be enabled by default on all architectures that support
MMU_GATHER_RCU_TABLE_FREE.

Considering that a large number of PTE page table pages (such as 100GB+)
can only be caused on a 64-bit system, let PT_RECLAIM also depend on
64BIT.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 arch/x86/Kconfig | 1 -
 mm/Kconfig       | 6 +-----
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index eac2e86056902..96bff81fd4787 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -330,7 +330,6 @@ 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 a5a90b169435d..e795fbd69e50c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1440,14 +1440,10 @@ 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
+	depends on MMU_GATHER_RCU_TABLE_FREE && MMU && SMP && 64BIT
 	help
 	  Try to reclaim empty user page table pages in paths other than munmap
 	  and exit_mmap path.
-- 
2.20.1