linux-kernel - Re: [PATCH v3 05/13] mm: introduce CONFIG_ARCH_LAZY

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Message-ID: <3836a43f-809e-419d-a85d-74606d9daa0f@arm.com>
Date: Mon, 20 Oct 2025 12:37:38 +0200
From: Kevin Brodsky <kevin.brodsky@....com>
To: Mike Rapoport <rppt@...nel.org>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Alexander Gordeev <agordeev@...ux.ibm.com>,
 Andreas Larsson <andreas@...sler.com>,
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 <bp@...en8.de>, Catalin Marinas <catalin.marinas@....com>,
 Christophe Leroy <christophe.leroy@...roup.eu>,
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 linux-arm-kernel@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
 sparclinux@...r.kernel.org, xen-devel@...ts.xenproject.org, x86@...nel.org
Subject: Re: [PATCH v3 05/13] mm: introduce CONFIG_ARCH_LAZY_MMU

On 18/10/2025 11:52, Mike Rapoport wrote:
>> @@ -231,7 +231,7 @@ static inline int pmd_dirty(pmd_t pmd)
>>   * held, but for kernel PTE updates, no lock is held). Nesting is not permitted
>>   * and the mode cannot be used in interrupt context.
>>   */
>> -#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
>> +#ifndef CONFIG_ARCH_LAZY_MMU
>>  static inline void arch_enter_lazy_mmu_mode(void) {}
>>  static inline void arch_leave_lazy_mmu_mode(void) {}
>>  static inline void arch_flush_lazy_mmu_mode(void) {}
>> diff --git a/mm/Kconfig b/mm/Kconfig
>> index 0e26f4fc8717..2fdcb42ca1a1 100644
>> --- a/mm/Kconfig
>> +++ b/mm/Kconfig
>> @@ -1372,6 +1372,9 @@ config PT_RECLAIM
>>  config FIND_NORMAL_PAGE
>>  	def_bool n
>>  
>> +config ARCH_LAZY_MMU
>> +	bool
>> +
> I think a better name would be ARCH_HAS_LAZY_MMU and the config option fits
> better to arch/Kconfig.

Sounds fine by me - I'm inclined to make it slightly longer still,
ARCH_HAS_LAZY_MMU_MODE, to avoid making "LAZY_MMU" sound like some HW
feature.

- Kevin