[PATCH v3 5/7] parisc: mm: enable MMU_GATHER_RCU_TABLE_FREE

Qi Zheng
2025-12-17T09:47:21Z

From: Qi Zheng <zhengqi.arch@bytedance.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@bytedance.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
---
arch/parisc/Kconfig | 1 +
arch/parisc/include/asm/tlb.h | 4 ++--
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 47fd9662d8005..62d5a89d5c7bc 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -79,6 +79,7 @@ config PARISC
select GENERIC_CLOCKEVENTS
select CPU_NO_EFFICIENT_FFS
select THREAD_INFO_IN_TASK
+ select MMU_GATHER_RCU_TABLE_FREE
select NEED_DMA_MAP_STATE
select NEED_SG_DMA_LENGTH
select HAVE_ARCH_KGDB
diff --git a/arch/parisc/include/asm/tlb.h b/arch/parisc/include/asm/tlb.h
index 44235f367674d..4501fee0a8fa4 100644
--- a/arch/parisc/include/asm/tlb.h
+++ b/arch/parisc/include/asm/tlb.h
@@ -5,8 +5,8 @@
#include <asm-generic/tlb.h>

#if CONFIG_PGTABLE_LEVELS == 3
-#define __pmd_free_tlb(tlb, pmd, addr) pmd_free((tlb)->mm, pmd)
+#define __pmd_free_tlb(tlb, pmd, addr) tlb_remove_ptdesc((tlb), virt_to_ptdesc(pmd))
#endif
-#define __pte_free_tlb(tlb, pte, addr) pte_free((tlb)->mm, pte)
+#define __pte_free_tlb(tlb, pte, addr) tlb_remove_ptdesc((tlb), page_ptdesc(pte))

#endif
--
2.20.1