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Subject: Re: [PATCH] mm/thp: Make ARCH_ENABLE_SPLIT_PMD_PTLOCK dependent on
 PGTABLE_LEVELS > 2
To:     linux-mm@kvack.org, akpm@linux-foundation.org
Cc:     Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, x86@kernel.org,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
References: <1620621345-29176-1-git-send-email-anshuman.khandual@arm.com>
From:   Anshuman Khandual <anshuman.khandual@arm.com>
Message-ID: <a4403be6-5b74-2c86-bc4c-42ae4f0764dc@arm.com>
Date:   Mon, 17 May 2021 09:45:31 +0530
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On 5/10/21 10:05 AM, Anshuman Khandual wrote:
> ARCH_ENABLE_SPLIT_PMD_PTLOCK is irrelevant unless there are two page table
> levels including PMD (also per Documentation/vm/split_page_table_lock.rst).
> Make this dependency explicit on remaining platforms i.e x86 and s390 where
> ARCH_ENABLE_SPLIT_PMD_PTLOCK is subscribed.
> 
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: x86@kernel.org
> Cc: linux-s390@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>  arch/s390/Kconfig | 2 +-
>  arch/x86/Kconfig  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index b4c7c34069f8..fcc1ea339a9d 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -62,7 +62,7 @@ config S390
>  	select ARCH_BINFMT_ELF_STATE
>  	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM
>  	select ARCH_ENABLE_MEMORY_HOTREMOVE
> -	select ARCH_ENABLE_SPLIT_PMD_PTLOCK
> +	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
>  	select ARCH_HAS_DEBUG_VM_PGTABLE
>  	select ARCH_HAS_DEBUG_WX
>  	select ARCH_HAS_DEVMEM_IS_ALLOWED
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 0045e1b44190..ec9e9d3d7e3f 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -63,7 +63,7 @@ config X86
>  	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
>  	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 || (X86_32 && HIGHMEM)
>  	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
> -	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if X86_64 || X86_PAE
> +	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
>  	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
>  	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
>  	select ARCH_HAS_CACHE_LINE_SIZE
> 


Gentle ping.

Any updates or objections ?