linux-kernel - [PATCH v2 2/7] alpha: mm: enable MMU_GATHER_RCU_TABLE

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Message-ID: <54381c49729449b9c3a09e78a69bf14b4b107774.1763537007.git.zhengqi.arch@bytedance.com>
Date: Wed, 19 Nov 2025 15:31:19 +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@...nel.org,
	ioworker0@...il.com,
	linmag7@...il.com
Cc: linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-alpha@...r.kernel.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>,
	Richard Henderson <richard.henderson@...aro.org>,
	Matt Turner <mattst88@...il.com>
Subject: [PATCH v2 2/7] alpha: mm: enable MMU_GATHER_RCU_TABLE_FREE

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

On a 64-bit system, madvise(MADV_DONTNEED) may cause a large number of
empty PTE page table pages (such as 100GB+). To resolve this problem,
first enable MMU_GATHER_RCU_TABLE_FREE to prepare for enabling the
PT_RECLAIM feature, which resolves this problem.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
Cc: Richard Henderson <richard.henderson@...aro.org>
Cc: Matt Turner <mattst88@...il.com>
---
 arch/alpha/Kconfig           | 1 +
 arch/alpha/include/asm/tlb.h | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 80367f2cf821c..6c7dbf0adad62 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -38,6 +38,7 @@ config ALPHA
 	select OLD_SIGSUSPEND
 	select CPU_NO_EFFICIENT_FFS if !ALPHA_EV67
 	select MMU_GATHER_NO_RANGE
+	select MMU_GATHER_RCU_TABLE_FREE
 	select SPARSEMEM_EXTREME if SPARSEMEM
 	select ZONE_DMA
 	help
diff --git a/arch/alpha/include/asm/tlb.h b/arch/alpha/include/asm/tlb.h
index 4f79e331af5ea..ad586b898fd6b 100644
--- a/arch/alpha/include/asm/tlb.h
+++ b/arch/alpha/include/asm/tlb.h
@@ -4,7 +4,7 @@
 
 #include <asm-generic/tlb.h>
 
-#define __pte_free_tlb(tlb, pte, address)		pte_free((tlb)->mm, pte)
-#define __pmd_free_tlb(tlb, pmd, address)		pmd_free((tlb)->mm, pmd)
- 
+#define __pte_free_tlb(tlb, pte, address)	tlb_remove_ptdesc((tlb), page_ptdesc(pte))
+#define __pmd_free_tlb(tlb, pmd, address)	tlb_remove_ptdesc((tlb), virt_to_ptdesc(pmd))
+
 #endif
-- 
2.20.1