[PATCH v4 0/8] enable PT_RECLAIM on more 64-bit architectures

[PATCH v4 0/8] enable PT_RECLAIM on more 64-bit architectures

[Qi Zheng]

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

Changes in v4:
 - convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config
 - fix a WARN_ON_ONCE() on sparc64 (and on ppc)
   (reported by Andreas Larsson)
 - collect Acked-by (Hi David, I've kept your Acked-by, feel free to drop it)
 - rebase onto the v6.19-rc7

Changes in v3:
 - modify the commit message in [PATCH v3 1/7] (suggested by David Hildenbrand)
 - make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE instead of 64BIT
 - collect Acked-by
 - rebase onto the next-20251217

Changelog in v2:
 - fix compilation errors (reported by Magnus Lindholm and kernel test robot)
 - adjust some code style (suggested by Huacai Chen)
 - make PT_RECLAIM user-unselectable (suggested by David Hildenbrand)
 - rebase onto the next-20251119

Hi all,

This series aims to enable PT_RECLAIM on more 64-bit architectures.

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, we need to enable
PT_RECLAIM, which depends on MMU_GATHER_RCU_TABLE_FREE.

For these architectures that define its own __tlb_remove_table(), since
their page tables are not of type struct ptdesc, they cannot be supported
PT_RECLAIM.

Therefore, this series first enables MMU_GATHER_RCU_TABLE_FREE on all 64-bit
architectures, then converts __HAVE_ARCH_TLB_REMOVE_TABLE to
CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config, and finally makes PT_RECLAIM depend on
MMU_GATHER_RCU_TABLE_FREE && !HAVE_ARCH_TLB_REMOVE_TABLE. This way, PT_RECLAIM
can be enabled by default on most 64-bit architectures.

Of course, this will also be enabled on some 32-bit architectures that already
support MMU_GATHER_RCU_TABLE_FREE. That's fine, PT_RECLAIM works well on all
32-bit architectures as well. Although the benefit isn't significant, there's
still memory that can be reclaimed. Perhaps PT_RECLAIM can be enabled on all
32-bit architectures in the future.

Comments and suggestions are welcome!

Thanks,
Qi

Qi Zheng (8):
  mm: change mm/pt_reclaim.c to use asm/tlb.h instead of
    asm-generic/tlb.h
  alpha: mm: enable MMU_GATHER_RCU_TABLE_FREE
  LoongArch: mm: enable MMU_GATHER_RCU_TABLE_FREE
  mips: mm: enable MMU_GATHER_RCU_TABLE_FREE
  parisc: mm: enable MMU_GATHER_RCU_TABLE_FREE
  um: mm: enable MMU_GATHER_RCU_TABLE_FREE
  mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to
    CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config
  mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE

 arch/alpha/Kconfig                   | 1 +
 arch/alpha/include/asm/tlb.h         | 6 +++---
 arch/loongarch/Kconfig               | 1 +
 arch/loongarch/include/asm/pgalloc.h | 7 +++----
 arch/mips/Kconfig                    | 1 +
 arch/mips/include/asm/pgalloc.h      | 7 +++----
 arch/parisc/Kconfig                  | 1 +
 arch/parisc/include/asm/tlb.h        | 4 ++--
 arch/powerpc/Kconfig                 | 1 +
 arch/powerpc/include/asm/tlb.h       | 1 -
 arch/sparc/Kconfig                   | 1 +
 arch/sparc/include/asm/tlb_64.h      | 1 -
 arch/um/Kconfig                      | 1 +
 arch/x86/Kconfig                     | 1 -
 include/asm-generic/tlb.h            | 2 +-
 mm/Kconfig                           | 8 +++-----
 mm/pt_reclaim.c                      | 2 +-
 17 files changed, 23 insertions(+), 23 deletions(-)

-- 
2.20.1

[PATCH v4 1/8] mm: change mm/pt_reclaim.c to use asm/tlb.h instead of asm-generic/tlb.h

[Qi Zheng]

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

Generally, the asm/tlb.h will include asm-generic/tlb.h, so change
mm/pt_reclaim.c to use asm/tlb.h instead of asm-generic/tlb.h. This is a
preparation for enabling CONFIG_PT_RECLAIM on other architectures, such as
alpha.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
---
 mm/pt_reclaim.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/pt_reclaim.c b/mm/pt_reclaim.c
index 0d9cfbf4fe5d8..46771cfff8239 100644
--- a/mm/pt_reclaim.c
+++ b/mm/pt_reclaim.c
@@ -2,7 +2,7 @@
 #include <linux/hugetlb.h>
 #include <linux/pgalloc.h>
 
-#include <asm-generic/tlb.h>
+#include <asm/tlb.h>
 
 #include "internal.h"
 
-- 
2.20.1

[PATCH v4 2/8] alpha: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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: Richard Henderson <richard.henderson@linaro.org>
Cc: Matt Turner <mattst88@gmail.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

[PATCH v4 3/8] LoongArch: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
---
 arch/loongarch/Kconfig               | 1 +
 arch/loongarch/include/asm/pgalloc.h | 7 +++----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 730f342145197..43d5b863e1fb2 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -187,6 +187,7 @@ config LOONGARCH
 	select IRQ_LOONGARCH_CPU
 	select LOCK_MM_AND_FIND_VMA
 	select MMU_GATHER_MERGE_VMAS if MMU
+	select MMU_GATHER_RCU_TABLE_FREE
 	select MODULES_USE_ELF_RELA if MODULES
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
 	select NEED_PER_CPU_PAGE_FIRST_CHUNK
diff --git a/arch/loongarch/include/asm/pgalloc.h b/arch/loongarch/include/asm/pgalloc.h
index 08dcc698ec184..248f62d0b590e 100644
--- a/arch/loongarch/include/asm/pgalloc.h
+++ b/arch/loongarch/include/asm/pgalloc.h
@@ -55,8 +55,7 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 	return pte;
 }
 
-#define __pte_free_tlb(tlb, pte, address)	\
-	tlb_remove_ptdesc((tlb), page_ptdesc(pte))
+#define __pte_free_tlb(tlb, pte, address)	tlb_remove_ptdesc((tlb), page_ptdesc(pte))
 
 #ifndef __PAGETABLE_PMD_FOLDED
 
@@ -79,7 +78,7 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 	return pmd;
 }
 
-#define __pmd_free_tlb(tlb, x, addr)	pmd_free((tlb)->mm, x)
+#define __pmd_free_tlb(tlb, x, addr)	tlb_remove_ptdesc((tlb), virt_to_ptdesc(x))
 
 #endif
 
@@ -99,7 +98,7 @@ static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
 	return pud;
 }
 
-#define __pud_free_tlb(tlb, x, addr)	pud_free((tlb)->mm, x)
+#define __pud_free_tlb(tlb, x, addr)	tlb_remove_ptdesc((tlb), virt_to_ptdesc(x))
 
 #endif /* __PAGETABLE_PUD_FOLDED */
 
-- 
2.20.1

[PATCH v4 4/8] mips: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
---
 arch/mips/Kconfig               | 1 +
 arch/mips/include/asm/pgalloc.h | 7 +++----
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b88b97139fa8e..c0c94e26ce396 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -99,6 +99,7 @@ config MIPS
 	select IRQ_FORCED_THREADING
 	select ISA if EISA
 	select LOCK_MM_AND_FIND_VMA
+	select MMU_GATHER_RCU_TABLE_FREE
 	select MODULES_USE_ELF_REL if MODULES
 	select MODULES_USE_ELF_RELA if MODULES && 64BIT
 	select PERF_USE_VMALLOC
diff --git a/arch/mips/include/asm/pgalloc.h b/arch/mips/include/asm/pgalloc.h
index 7a04381efa0b5..895bf79e76762 100644
--- a/arch/mips/include/asm/pgalloc.h
+++ b/arch/mips/include/asm/pgalloc.h
@@ -48,8 +48,7 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 extern void pgd_init(void *addr);
 extern pgd_t *pgd_alloc(struct mm_struct *mm);
 
-#define __pte_free_tlb(tlb, pte, address)	\
-	tlb_remove_ptdesc((tlb), page_ptdesc(pte))
+#define __pte_free_tlb(tlb, pte, address)	tlb_remove_ptdesc((tlb), page_ptdesc(pte))
 
 #ifndef __PAGETABLE_PMD_FOLDED
 
@@ -72,7 +71,7 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 	return pmd;
 }
 
-#define __pmd_free_tlb(tlb, x, addr)	pmd_free((tlb)->mm, x)
+#define __pmd_free_tlb(tlb, x, addr)	tlb_remove_ptdesc((tlb), virt_to_ptdesc(x))
 
 #endif
 
@@ -97,7 +96,7 @@ static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4d, pud_t *pud)
 	set_p4d(p4d, __p4d((unsigned long)pud));
 }
 
-#define __pud_free_tlb(tlb, x, addr)	pud_free((tlb)->mm, x)
+#define __pud_free_tlb(tlb, x, addr)	tlb_remove_ptdesc((tlb), virt_to_ptdesc(x))
 
 #endif /* __PAGETABLE_PUD_FOLDED */
 
-- 
2.20.1

[PATCH v4 5/8] parisc: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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

[PATCH v4 6/8] um: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
---
 arch/um/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 8415d39b0d430..098cda44db225 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -42,6 +42,7 @@ config UML
 	select HAVE_SYSCALL_TRACEPOINTS
 	select THREAD_INFO_IN_TASK
 	select SPARSE_IRQ
+	select MMU_GATHER_RCU_TABLE_FREE
 
 config MMU
 	bool
-- 
2.20.1

[PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[Qi Zheng]

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

For architectures that define __HAVE_ARCH_TLB_REMOVE_TABLE, the page
tables at the pmd/pud level are generally not of struct ptdesc type, and
do not have pt_rcu_head member, thus these architectures cannot support
PT_RECLAIM.

In preparation for enabling PT_RECLAIM on more architectures, convert
__HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config,
so that we can make conditional judgments in Kconfig.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 arch/powerpc/Kconfig            | 1 +
 arch/powerpc/include/asm/tlb.h  | 1 -
 arch/sparc/Kconfig              | 1 +
 arch/sparc/include/asm/tlb_64.h | 1 -
 include/asm-generic/tlb.h       | 2 +-
 mm/Kconfig                      | 3 +++
 6 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9537a61ebae02..b47aa8fd62742 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -304,6 +304,7 @@ config PPC
 	select LOCK_MM_AND_FIND_VMA
 	select MMU_GATHER_PAGE_SIZE
 	select MMU_GATHER_RCU_TABLE_FREE
+	select HAVE_ARCH_TLB_REMOVE_TABLE
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_LAZY_TLB_SHOOTDOWN		if PPC_BOOK3S_64
 	select MODULES_USE_ELF_RELA
diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
index 2058e8d3e0138..1ca7d4c4b90db 100644
--- a/arch/powerpc/include/asm/tlb.h
+++ b/arch/powerpc/include/asm/tlb.h
@@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather *tlb);
  */
 #define tlb_needs_table_invalidate()	radix_enabled()
 
-#define __HAVE_ARCH_TLB_REMOVE_TABLE
 /* Get the generic bits... */
 #include <asm-generic/tlb.h>
 
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index a630d373e6453..25fa2908d6152 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -74,6 +74,7 @@ config SPARC64
 	select HAVE_KRETPROBES
 	select HAVE_KPROBES
 	select MMU_GATHER_RCU_TABLE_FREE if SMP
+	select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_GATHER_NO_FLUSH_CACHE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/sparc/include/asm/tlb_64.h b/arch/sparc/include/asm/tlb_64.h
index 1a6e694418e39..3037187482db7 100644
--- a/arch/sparc/include/asm/tlb_64.h
+++ b/arch/sparc/include/asm/tlb_64.h
@@ -33,7 +33,6 @@ void flush_tlb_pending(void);
 #define tlb_needs_table_invalidate()	(false)
 #endif
 
-#define __HAVE_ARCH_TLB_REMOVE_TABLE
 #include <asm-generic/tlb.h>
 
 #endif /* _SPARC64_TLB_H */
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 4d679d2a206b4..3427b8036ba33 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -213,7 +213,7 @@ struct mmu_table_batch {
 #define MAX_TABLE_BATCH		\
 	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
 
-#ifndef __HAVE_ARCH_TLB_REMOVE_TABLE
+#ifndef CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE
 static inline void __tlb_remove_table(void *table)
 {
 	struct ptdesc *ptdesc = (struct ptdesc *)table;
diff --git a/mm/Kconfig b/mm/Kconfig
index a992f2203eb91..456e9eaedca39 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1451,6 +1451,9 @@ 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 HAVE_ARCH_TLB_REMOVE_TABLE
+	def_bool n
+
 config ARCH_SUPPORTS_PT_RECLAIM
 	def_bool n
 
-- 
2.20.1

[PATCH v4 8/8] mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE

[Qi Zheng]

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

The PT_RECLAIM can work on all architectures that support
MMU_GATHER_RCU_TABLE_FREE, except for those that have selected
HAVE_ARCH_TLB_REMOVE_TABLE,so make PT_RECLAIM depends on
MMU_GATHER_RCU_TABLE_FREE && !HAVE_ARCH_TLB_REMOVE_TABLE.

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>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
---
 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 456e9eaedca39..1f3109b164d86 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1454,14 +1454,9 @@ config ARCH_HAS_USER_SHADOW_STACK
 config HAVE_ARCH_TLB_REMOVE_TABLE
 	def_bool n
 
-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 && !HAVE_ARCH_TLB_REMOVE_TABLE
 	help
 	  Try to reclaim empty user page table pages in paths other than munmap
 	  and exit_mmap path.
-- 
2.20.1

Re: [PATCH v4 0/8] enable PT_RECLAIM on more 64-bit architectures

[Andrew Morton]

On Tue, 27 Jan 2026 20:12:53 +0800 Qi Zheng <qi.zheng@linux.dev> wrote:

> This series aims to enable PT_RECLAIM on more 64-bit architectures.

Thanks, I updated mm.git's mm-unstable branch to v4.

> Changes in v4:
>  - convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config
>  - fix a WARN_ON_ONCE() on sparc64 (and on ppc)
>    (reported by Andreas Larsson)
>  - collect Acked-by (Hi David, I've kept your Acked-by, feel free to drop it)
>  - rebase onto the v6.19-rc7
> 

Below is how v4 altered mm.git.

I'm not seeing the WARN_ON_ONCE() fix.  I assume that was due to the
Kconfig alterations?



--- a/arch/powerpc/include/asm/tlb.h~b
+++ a/arch/powerpc/include/asm/tlb.h
@@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather
  */
 #define tlb_needs_table_invalidate()	radix_enabled()
 
-#define __HAVE_ARCH_TLB_REMOVE_TABLE
 /* Get the generic bits... */
 #include <asm-generic/tlb.h>
 
--- a/arch/powerpc/Kconfig~b
+++ a/arch/powerpc/Kconfig
@@ -305,6 +305,7 @@ config PPC
 	select LOCK_MM_AND_FIND_VMA
 	select MMU_GATHER_PAGE_SIZE
 	select MMU_GATHER_RCU_TABLE_FREE
+	select HAVE_ARCH_TLB_REMOVE_TABLE
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_LAZY_TLB_SHOOTDOWN		if PPC_BOOK3S_64
 	select MODULES_USE_ELF_RELA
--- a/arch/sparc/include/asm/tlb_64.h~b
+++ a/arch/sparc/include/asm/tlb_64.h
@@ -33,7 +33,6 @@ void flush_tlb_pending(void);
 #define tlb_needs_table_invalidate()	(false)
 #endif
 
-#define __HAVE_ARCH_TLB_REMOVE_TABLE
 #include <asm-generic/tlb.h>
 
 #endif /* _SPARC64_TLB_H */
--- a/arch/sparc/Kconfig~b
+++ a/arch/sparc/Kconfig
@@ -74,6 +74,7 @@ config SPARC64
 	select HAVE_KRETPROBES
 	select HAVE_KPROBES
 	select MMU_GATHER_RCU_TABLE_FREE if SMP
+	select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_GATHER_NO_FLUSH_CACHE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
--- a/include/asm-generic/tlb.h~b
+++ a/include/asm-generic/tlb.h
@@ -213,7 +213,7 @@ struct mmu_table_batch {
 #define MAX_TABLE_BATCH		\
 	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
 
-#ifndef __HAVE_ARCH_TLB_REMOVE_TABLE
+#ifndef CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE
 static inline void __tlb_remove_table(void *table)
 {
 	struct ptdesc *ptdesc = (struct ptdesc *)table;
--- a/mm/Kconfig~b
+++ a/mm/Kconfig
@@ -1448,9 +1448,12 @@ 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 HAVE_ARCH_TLB_REMOVE_TABLE
+	def_bool n
+
 config PT_RECLAIM
 	def_bool y
-	depends on MMU_GATHER_RCU_TABLE_FREE
+	depends on MMU_GATHER_RCU_TABLE_FREE && !HAVE_ARCH_TLB_REMOVE_TABLE
 	help
 	  Try to reclaim empty user page table pages in paths other than munmap
 	  and exit_mmap path.
_

Re: [PATCH v4 0/8] enable PT_RECLAIM on more 64-bit architectures

[Qi Zheng]

On 1/28/26 4:46 AM, Andrew Morton wrote:
> On Tue, 27 Jan 2026 20:12:53 +0800 Qi Zheng <qi.zheng@linux.dev> wrote:
> 
>> This series aims to enable PT_RECLAIM on more 64-bit architectures.
> 
> Thanks, I updated mm.git's mm-unstable branch to v4.
> 
>> Changes in v4:
>>   - convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config
>>   - fix a WARN_ON_ONCE() on sparc64 (and on ppc)
>>     (reported by Andreas Larsson)
>>   - collect Acked-by (Hi David, I've kept your Acked-by, feel free to drop it)
>>   - rebase onto the v6.19-rc7
>>
> 
> Below is how v4 altered mm.git.
> 
> I'm not seeing the WARN_ON_ONCE() fix.  I assume that was due to the
> Kconfig alterations?

Yes, sparc64 and ppc will select HAVE_ARCH_TLB_REMOVE_TABLE, so
PT_RECLAIM will not be enabled. This means it won't affect
sparc64 and ppc, and will not trigger WARN_ON_ONCE().

I don't have a testing environment for sparc64 and ppc, but I
expect it should be able to fix the WARN_ON_ONCE().

Thanks,
Qi

> 
> 
> 
> --- a/arch/powerpc/include/asm/tlb.h~b
> +++ a/arch/powerpc/include/asm/tlb.h
> @@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather
>    */
>   #define tlb_needs_table_invalidate()	radix_enabled()
>   
> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>   /* Get the generic bits... */
>   #include <asm-generic/tlb.h>
>   
> --- a/arch/powerpc/Kconfig~b
> +++ a/arch/powerpc/Kconfig
> @@ -305,6 +305,7 @@ config PPC
>   	select LOCK_MM_AND_FIND_VMA
>   	select MMU_GATHER_PAGE_SIZE
>   	select MMU_GATHER_RCU_TABLE_FREE
> +	select HAVE_ARCH_TLB_REMOVE_TABLE
>   	select MMU_GATHER_MERGE_VMAS
>   	select MMU_LAZY_TLB_SHOOTDOWN		if PPC_BOOK3S_64
>   	select MODULES_USE_ELF_RELA
> --- a/arch/sparc/include/asm/tlb_64.h~b
> +++ a/arch/sparc/include/asm/tlb_64.h
> @@ -33,7 +33,6 @@ void flush_tlb_pending(void);
>   #define tlb_needs_table_invalidate()	(false)
>   #endif
>   
> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>   #include <asm-generic/tlb.h>
>   
>   #endif /* _SPARC64_TLB_H */
> --- a/arch/sparc/Kconfig~b
> +++ a/arch/sparc/Kconfig
> @@ -74,6 +74,7 @@ config SPARC64
>   	select HAVE_KRETPROBES
>   	select HAVE_KPROBES
>   	select MMU_GATHER_RCU_TABLE_FREE if SMP
> +	select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
>   	select MMU_GATHER_MERGE_VMAS
>   	select MMU_GATHER_NO_FLUSH_CACHE
>   	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> --- a/include/asm-generic/tlb.h~b
> +++ a/include/asm-generic/tlb.h
> @@ -213,7 +213,7 @@ struct mmu_table_batch {
>   #define MAX_TABLE_BATCH		\
>   	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
>   
> -#ifndef __HAVE_ARCH_TLB_REMOVE_TABLE
> +#ifndef CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE
>   static inline void __tlb_remove_table(void *table)
>   {
>   	struct ptdesc *ptdesc = (struct ptdesc *)table;
> --- a/mm/Kconfig~b
> +++ a/mm/Kconfig
> @@ -1448,9 +1448,12 @@ 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 HAVE_ARCH_TLB_REMOVE_TABLE
> +	def_bool n
> +
>   config PT_RECLAIM
>   	def_bool y
> -	depends on MMU_GATHER_RCU_TABLE_FREE
> +	depends on MMU_GATHER_RCU_TABLE_FREE && !HAVE_ARCH_TLB_REMOVE_TABLE
>   	help
>   	  Try to reclaim empty user page table pages in paths other than munmap
>   	  and exit_mmap path.
> _
> 

Re: [PATCH v4 2/8] alpha: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Magnus Lindholm]

On Tue, Jan 27, 2026 at 1:16 PM Qi Zheng <qi.zheng@linux.dev> wrote:
>
> 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: Richard Henderson <richard.henderson@linaro.org>
> Cc: Matt Turner <mattst88@gmail.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
>

Looks good from an Alpha perspective.

Acked-by: Magnus Lindholm <linmag7@gmail.com>

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[David Hildenbrand (Arm)]

On 1/27/26 13:13, Qi Zheng wrote:
> From: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> For architectures that define __HAVE_ARCH_TLB_REMOVE_TABLE, the page
> tables at the pmd/pud level are generally not of struct ptdesc type, and
> do not have pt_rcu_head member, thus these architectures cannot support
> PT_RECLAIM.
> 
> In preparation for enabling PT_RECLAIM on more architectures, convert
> __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config,
> so that we can make conditional judgments in Kconfig.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> ---
>   arch/powerpc/Kconfig            | 1 +
>   arch/powerpc/include/asm/tlb.h  | 1 -
>   arch/sparc/Kconfig              | 1 +
>   arch/sparc/include/asm/tlb_64.h | 1 -
>   include/asm-generic/tlb.h       | 2 +-
>   mm/Kconfig                      | 3 +++
>   6 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 9537a61ebae02..b47aa8fd62742 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -304,6 +304,7 @@ config PPC
>   	select LOCK_MM_AND_FIND_VMA
>   	select MMU_GATHER_PAGE_SIZE
>   	select MMU_GATHER_RCU_TABLE_FREE
> +	select HAVE_ARCH_TLB_REMOVE_TABLE
>   	select MMU_GATHER_MERGE_VMAS
>   	select MMU_LAZY_TLB_SHOOTDOWN		if PPC_BOOK3S_64
>   	select MODULES_USE_ELF_RELA
> diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h
> index 2058e8d3e0138..1ca7d4c4b90db 100644
> --- a/arch/powerpc/include/asm/tlb.h
> +++ b/arch/powerpc/include/asm/tlb.h
> @@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather *tlb);
>    */
>   #define tlb_needs_table_invalidate()	radix_enabled()
>   
> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>   /* Get the generic bits... */
>   #include <asm-generic/tlb.h>
>   
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index a630d373e6453..25fa2908d6152 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -74,6 +74,7 @@ config SPARC64
>   	select HAVE_KRETPROBES
>   	select HAVE_KPROBES
>   	select MMU_GATHER_RCU_TABLE_FREE if SMP
> +	select HAVE_ARCH_TLB_REMOVE_TABLE if SMP

Why the SMP? At least in tlb_64.h, it was not protected by SMP IIUC.

Apart from that LGTM.

-- 
Cheers,

David

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[Qi Zheng]

On 2/6/26 7:06 PM, David Hildenbrand (Arm) wrote:
> On 1/27/26 13:13, Qi Zheng wrote:
>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>
>> For architectures that define __HAVE_ARCH_TLB_REMOVE_TABLE, the page
>> tables at the pmd/pud level are generally not of struct ptdesc type, and
>> do not have pt_rcu_head member, thus these architectures cannot support
>> PT_RECLAIM.
>>
>> In preparation for enabling PT_RECLAIM on more architectures, convert
>> __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config,
>> so that we can make conditional judgments in Kconfig.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>> ---
>>   arch/powerpc/Kconfig            | 1 +
>>   arch/powerpc/include/asm/tlb.h  | 1 -
>>   arch/sparc/Kconfig              | 1 +
>>   arch/sparc/include/asm/tlb_64.h | 1 -
>>   include/asm-generic/tlb.h       | 2 +-
>>   mm/Kconfig                      | 3 +++
>>   6 files changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 9537a61ebae02..b47aa8fd62742 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -304,6 +304,7 @@ config PPC
>>       select LOCK_MM_AND_FIND_VMA
>>       select MMU_GATHER_PAGE_SIZE
>>       select MMU_GATHER_RCU_TABLE_FREE
>> +    select HAVE_ARCH_TLB_REMOVE_TABLE
>>       select MMU_GATHER_MERGE_VMAS
>>       select MMU_LAZY_TLB_SHOOTDOWN        if PPC_BOOK3S_64
>>       select MODULES_USE_ELF_RELA
>> diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/ 
>> asm/tlb.h
>> index 2058e8d3e0138..1ca7d4c4b90db 100644
>> --- a/arch/powerpc/include/asm/tlb.h
>> +++ b/arch/powerpc/include/asm/tlb.h
>> @@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather *tlb);
>>    */
>>   #define tlb_needs_table_invalidate()    radix_enabled()
>> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>>   /* Get the generic bits... */
>>   #include <asm-generic/tlb.h>
>> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>> index a630d373e6453..25fa2908d6152 100644
>> --- a/arch/sparc/Kconfig
>> +++ b/arch/sparc/Kconfig
>> @@ -74,6 +74,7 @@ config SPARC64
>>       select HAVE_KRETPROBES
>>       select HAVE_KPROBES
>>       select MMU_GATHER_RCU_TABLE_FREE if SMP
>> +    select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
> 
> Why the SMP? At least in tlb_64.h, it was not protected by SMP IIUC.

Ah, It's just simply aligned with the MMU_GATHER_RCU_TABLE_FREE above.

> 
> Apart from that LGTM.

Thanks!

> 

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[David Hildenbrand (Arm)]

On 2/6/26 12:13, Qi Zheng wrote:
> 
> 
> On 2/6/26 7:06 PM, David Hildenbrand (Arm) wrote:
>> On 1/27/26 13:13, Qi Zheng wrote:
>>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>>
>>> For architectures that define __HAVE_ARCH_TLB_REMOVE_TABLE, the page
>>> tables at the pmd/pud level are generally not of struct ptdesc type, and
>>> do not have pt_rcu_head member, thus these architectures cannot support
>>> PT_RECLAIM.
>>>
>>> In preparation for enabling PT_RECLAIM on more architectures, convert
>>> __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE 
>>> config,
>>> so that we can make conditional judgments in Kconfig.
>>>
>>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>>> ---
>>>   arch/powerpc/Kconfig            | 1 +
>>>   arch/powerpc/include/asm/tlb.h  | 1 -
>>>   arch/sparc/Kconfig              | 1 +
>>>   arch/sparc/include/asm/tlb_64.h | 1 -
>>>   include/asm-generic/tlb.h       | 2 +-
>>>   mm/Kconfig                      | 3 +++
>>>   6 files changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>>> index 9537a61ebae02..b47aa8fd62742 100644
>>> --- a/arch/powerpc/Kconfig
>>> +++ b/arch/powerpc/Kconfig
>>> @@ -304,6 +304,7 @@ config PPC
>>>       select LOCK_MM_AND_FIND_VMA
>>>       select MMU_GATHER_PAGE_SIZE
>>>       select MMU_GATHER_RCU_TABLE_FREE
>>> +    select HAVE_ARCH_TLB_REMOVE_TABLE
>>>       select MMU_GATHER_MERGE_VMAS
>>>       select MMU_LAZY_TLB_SHOOTDOWN        if PPC_BOOK3S_64
>>>       select MODULES_USE_ELF_RELA
>>> diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/ 
>>> asm/tlb.h
>>> index 2058e8d3e0138..1ca7d4c4b90db 100644
>>> --- a/arch/powerpc/include/asm/tlb.h
>>> +++ b/arch/powerpc/include/asm/tlb.h
>>> @@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather *tlb);
>>>    */
>>>   #define tlb_needs_table_invalidate()    radix_enabled()
>>> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>>>   /* Get the generic bits... */
>>>   #include <asm-generic/tlb.h>
>>> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>>> index a630d373e6453..25fa2908d6152 100644
>>> --- a/arch/sparc/Kconfig
>>> +++ b/arch/sparc/Kconfig
>>> @@ -74,6 +74,7 @@ config SPARC64
>>>       select HAVE_KRETPROBES
>>>       select HAVE_KPROBES
>>>       select MMU_GATHER_RCU_TABLE_FREE if SMP
>>> +    select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
>>
>> Why the SMP? At least in tlb_64.h, it was not protected by SMP IIUC.
> 
> Ah, It's just simply aligned with the MMU_GATHER_RCU_TABLE_FREE above.

But does that work as expected for !SMP?

-- 
Cheers,

David

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[Qi Zheng]

On 2/6/26 7:45 PM, David Hildenbrand (Arm) wrote:
> On 2/6/26 12:13, Qi Zheng wrote:
>>
>>
>> On 2/6/26 7:06 PM, David Hildenbrand (Arm) wrote:
>>> On 1/27/26 13:13, Qi Zheng wrote:
>>>> From: Qi Zheng <zhengqi.arch@bytedance.com>
>>>>
>>>> For architectures that define __HAVE_ARCH_TLB_REMOVE_TABLE, the page
>>>> tables at the pmd/pud level are generally not of struct ptdesc type, 
>>>> and
>>>> do not have pt_rcu_head member, thus these architectures cannot support
>>>> PT_RECLAIM.
>>>>
>>>> In preparation for enabling PT_RECLAIM on more architectures, convert
>>>> __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE 
>>>> config,
>>>> so that we can make conditional judgments in Kconfig.
>>>>
>>>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
>>>> ---
>>>>   arch/powerpc/Kconfig            | 1 +
>>>>   arch/powerpc/include/asm/tlb.h  | 1 -
>>>>   arch/sparc/Kconfig              | 1 +
>>>>   arch/sparc/include/asm/tlb_64.h | 1 -
>>>>   include/asm-generic/tlb.h       | 2 +-
>>>>   mm/Kconfig                      | 3 +++
>>>>   6 files changed, 6 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>>>> index 9537a61ebae02..b47aa8fd62742 100644
>>>> --- a/arch/powerpc/Kconfig
>>>> +++ b/arch/powerpc/Kconfig
>>>> @@ -304,6 +304,7 @@ config PPC
>>>>       select LOCK_MM_AND_FIND_VMA
>>>>       select MMU_GATHER_PAGE_SIZE
>>>>       select MMU_GATHER_RCU_TABLE_FREE
>>>> +    select HAVE_ARCH_TLB_REMOVE_TABLE
>>>>       select MMU_GATHER_MERGE_VMAS
>>>>       select MMU_LAZY_TLB_SHOOTDOWN        if PPC_BOOK3S_64
>>>>       select MODULES_USE_ELF_RELA
>>>> diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/ 
>>>> asm/tlb.h
>>>> index 2058e8d3e0138..1ca7d4c4b90db 100644
>>>> --- a/arch/powerpc/include/asm/tlb.h
>>>> +++ b/arch/powerpc/include/asm/tlb.h
>>>> @@ -37,7 +37,6 @@ extern void tlb_flush(struct mmu_gather *tlb);
>>>>    */
>>>>   #define tlb_needs_table_invalidate()    radix_enabled()
>>>> -#define __HAVE_ARCH_TLB_REMOVE_TABLE
>>>>   /* Get the generic bits... */
>>>>   #include <asm-generic/tlb.h>
>>>> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
>>>> index a630d373e6453..25fa2908d6152 100644
>>>> --- a/arch/sparc/Kconfig
>>>> +++ b/arch/sparc/Kconfig
>>>> @@ -74,6 +74,7 @@ config SPARC64
>>>>       select HAVE_KRETPROBES
>>>>       select HAVE_KPROBES
>>>>       select MMU_GATHER_RCU_TABLE_FREE if SMP
>>>> +    select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
>>>
>>> Why the SMP? At least in tlb_64.h, it was not protected by SMP IIUC.
>>
>> Ah, It's just simply aligned with the MMU_GATHER_RCU_TABLE_FREE above.
> 
> But does that work as expected for !SMP?

In the case of !SMP, tlb_remove_table() will not be called:

static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, 
bool is_page)
{
	pgtable_free(table, is_page);
}


so I think it's okay to only select it in case of SMP.

> 

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[David Hildenbrand (Arm)]

On 2/6/26 12:58, Qi Zheng wrote:
> 
> 
> On 2/6/26 7:45 PM, David Hildenbrand (Arm) wrote:
>> On 2/6/26 12:13, Qi Zheng wrote:
>>>
>>>
>>>
>>> Ah, It's just simply aligned with the MMU_GATHER_RCU_TABLE_FREE above.
>>
>> But does that work as expected for !SMP?
> 
> In the case of !SMP, tlb_remove_table() will not be called:
> 
> static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, 
> bool is_page)
> {
>      pgtable_free(table, is_page);
> }

Ah, okay. Confusing stuff. Would have been nice to document/mention that 
in the patch description.

So if it compiles, all good

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David

Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

[Andreas Larsson]

On 2026-02-06 13:59, David Hildenbrand (Arm) wrote:
> On 2/6/26 12:58, Qi Zheng wrote:
>>
>>
>> On 2/6/26 7:45 PM, David Hildenbrand (Arm) wrote:
>>> On 2/6/26 12:13, Qi Zheng wrote:
>>>>
>>>>
>>>>
>>>> Ah, It's just simply aligned with the MMU_GATHER_RCU_TABLE_FREE above.
>>>
>>> But does that work as expected for !SMP?
>>
>> In the case of !SMP, tlb_remove_table() will not be called:
>>
>> static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, bool is_page)
>> {
>>      pgtable_free(table, is_page);
>> }
> 
> Ah, okay. Confusing stuff. Would have been nice to document/mention that in the patch description.
> 
> So if it compiles, all good
> 
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> 

It looks a bit weird, but it is actually more logically correct than
before the patch. Before this in the !SMP sparc64 case
__HAVE_ARCH_TLB_REMOVE_TABLE was defined even with no actual
__tlb_remove_table() present. But it did not matter in practice.
But I agree that a mention would not hurt.

Tested both with SMP and !SMP

Tested-by: Andreas Larsson <andreas@gaisler.com> #sparc
Acked-by: Andreas Larsson <andreas@gaisler.com> #sparc

Cheers,
Andreas

Re: [PATCH v4 5/8] parisc: mm: enable MMU_GATHER_RCU_TABLE_FREE

[Helge Deller]

On 1/27/26 13:12, Qi Zheng wrote:
> 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(-)

Acked-by: Helge Deller <deller@gmx.de>   # parisc
Tested-by: Helge Deller <deller@gmx.de>  # parisc

Thanks!
Helge