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: <53a1bbdd-26d1-454d-af06-169172278718@linux.dev>
Date: Fri, 6 Feb 2026 19:58:47 +0800
From: Qi Zheng <qi.zheng@...ux.dev>
To: "David Hildenbrand (Arm)" <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, 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 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@...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?

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.

>