linux-kernel - Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to CONFIG_HAVE_ARCH_TLB_REMOVE

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Message-ID: <538fef61-3903-407e-8486-538a28b99e9d@kernel.org>
Date: Fri, 6 Feb 2026 12:45:53 +0100
From: "David Hildenbrand (Arm)" <david@...nel.org>
To: Qi Zheng <qi.zheng@...ux.dev>, 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, akpm@...ux-foundation.org
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, sparclinux@...r.kernel.org,
 Qi Zheng <zhengqi.arch@...edance.com>
Subject: Re: [PATCH v4 7/8] mm: convert __HAVE_ARCH_TLB_REMOVE_TABLE to
 CONFIG_HAVE_ARCH_TLB_REMOVE_TABLE config

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@...edance.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@...edance.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