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

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Message-Id: <20260127124642.480123beb01ebb487f986a09@linux-foundation.org>
Date: Tue, 27 Jan 2026 12:46:42 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Qi Zheng <qi.zheng@...ux.dev>
Cc: david@...nel.org, andreas@...sler.com, richard.weiyang@...il.com,
 will@...nel.org, peterz@...radead.org, aneesh.kumar@...nel.org,
 npiggin@...il.com, dev.jain@....com, ioworker0@...il.com,
 linmag7@...il.com, 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, sparclinux@...r.kernel.org, Qi Zheng
 <zhengqi.arch@...edance.com>
Subject: Re: [PATCH v4 0/8] enable PT_RECLAIM on more 64-bit architectures

On Tue, 27 Jan 2026 20:12:53 +0800 Qi Zheng <qi.zheng@...ux.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.
_