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

Qi Zheng
2025-11-14T11:14:01Z

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 | 6 ++++--
2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 47fd9662d8005..946cbe21a4118 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -92,6 +92,7 @@ config PARISC
select TRACE_IRQFLAGS_SUPPORT
select HAVE_FUNCTION_DESCRIPTORS if 64BIT
select PCI_MSI_ARCH_FALLBACKS if PCI_MSI
+ select MMU_GATHER_RCU_TABLE_FREE

help
The PA-RISC microprocessor is designed by Hewlett-Packard and used
diff --git a/arch/parisc/include/asm/tlb.h b/arch/parisc/include/asm/tlb.h
index 44235f367674d..ab7d4113df61a 100644
--- a/arch/parisc/include/asm/tlb.h
+++ b/arch/parisc/include/asm/tlb.h
@@ -5,8 +5,10 @@
#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