linux-kernel - Re: [PATCH] mm: Remove pud_user() from asm-generic/pgtable-nopmd.h

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Message-ID: <aJtr38x3A1o1Q7dH@arm.com>
Date: Tue, 12 Aug 2025 17:29:19 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Will Deacon <will@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
	Arnd Bergmann <arnd@...db.de>, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
	linux-arch@...r.kernel.org, Peter Xu <peterx@...hat.com>,
	Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH] mm: Remove pud_user() from asm-generic/pgtable-nopmd.h

On Tue, Aug 12, 2025 at 01:14:19PM +0200, Christophe Leroy wrote:
> Commit 2c8a81dc0cc5 ("riscv/mm: fix two page table check related
> issues") added pud_user() in include/asm-generic/pgtable-nopmd.h
> 
> But pud_user() only exists on ARM64 and RISCV and is not expected
> by any part of MM.
> 
> Add the missing definition in arch/riscv/include/asm/pgtable-32.h
> and remove it from asm-generic/pgtable-nopmd.h
> 
> A stub pud_user() is also required for ARM64 after
> commit ed928a3402d8 ("arm64/mm: fix page table check compile
> error for CONFIG_PGTABLE_LEVELS=2")
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> Reviewed-by: Peter Xu <peterx@...hat.com>
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> ---
>  arch/arm64/include/asm/pgtable.h    | 1 +
>  arch/riscv/include/asm/pgtable-32.h | 5 +++++
>  include/asm-generic/pgtable-nopmd.h | 1 -
>  3 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index abd2dee416b3b..fef7cc7a340d8 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -955,6 +955,7 @@ static inline pmd_t *pud_pgtable(pud_t pud)
>  
>  #define pud_valid(pud)		false
>  #define pud_page_paddr(pud)	({ BUILD_BUG(); 0; })
> +#define pud_user		false /* Always 0 with folding */

Doesn't pud_user take an argument? With that fixed:

Acked-by: Catalin Marinas <catalin.marinas@....com>

(strangely I couldn't get the build to fail without a pud_user
definition, even with the PGTABLE_LEVELS=2 and PAGE_TABLE_CHECK=y
configuration)