linux-kernel - Re: [PATCH V4 mm-hotfixes 1/3] mm: move page table sync declarations to linux/pgtable.h

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Message-ID: <aJmkX3JBhH3F0PEC@kernel.org>
Date: Mon, 11 Aug 2025 11:05:51 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Harry Yoo <harry.yoo@...cle.com>
Cc: Dennis Zhou <dennis@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>, x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Tejun Heo <tj@...nel.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Christoph Lameter <cl@...two.org>,
	David Hildenbrand <david@...hat.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	"H. Peter Anvin" <hpa@...or.com>, kasan-dev@...glegroups.com,
	Ard Biesheuvel <ardb@...nel.org>, linux-kernel@...r.kernel.org,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Thomas Huth <thuth@...hat.com>, John Hubbard <jhubbard@...dia.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Michal Hocko <mhocko@...e.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, linux-mm@...ck.org,
	"Kirill A. Shutemov" <kas@...nel.org>,
	Oscar Salvador <osalvador@...e.de>, Jane Chu <jane.chu@...cle.com>,
	Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
	Joerg Roedel <joro@...tes.org>,
	Alistair Popple <apopple@...dia.com>,
	Joao Martins <joao.m.martins@...cle.com>,
	linux-arch@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH V4 mm-hotfixes 1/3] mm: move page table sync declarations
 to linux/pgtable.h

On Mon, Aug 11, 2025 at 02:34:18PM +0900, Harry Yoo wrote:
> Move ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to
> linux/pgtable.h so that they can be used outside of vmalloc and ioremap.
> 
> Cc: <stable@...r.kernel.org>
> Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
> Signed-off-by: Harry Yoo <harry.yoo@...cle.com>
> ---
>  include/linux/pgtable.h | 16 ++++++++++++++++
>  include/linux/vmalloc.h | 16 ----------------
>  2 files changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 4c035637eeb7..ba699df6ef69 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -1467,6 +1467,22 @@ static inline void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned
>  }
>  #endif
>  
> +/*
> + * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
> + * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()

If ARCH_PAGE_TABLE_SYNC_MASK can be used outside vmalloc(), the comment
needs an update, maybe

... and let the generic code that modifies kernel page tables

Other than that

Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>

> + * needs to be called.
> + */
> +#ifndef ARCH_PAGE_TABLE_SYNC_MASK
> +#define ARCH_PAGE_TABLE_SYNC_MASK 0
> +#endif
> +
> +/*
> + * There is no default implementation for arch_sync_kernel_mappings(). It is
> + * relied upon the compiler to optimize calls out if ARCH_PAGE_TABLE_SYNC_MASK
> + * is 0.
> + */
> +void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
> +
>  #endif /* CONFIG_MMU */
>  
>  /*
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index fdc9aeb74a44..2759dac6be44 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -219,22 +219,6 @@ extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
>  int vmap_pages_range(unsigned long addr, unsigned long end, pgprot_t prot,
>  		     struct page **pages, unsigned int page_shift);
>  
> -/*
> - * Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
> - * and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
> - * needs to be called.
> - */
> -#ifndef ARCH_PAGE_TABLE_SYNC_MASK
> -#define ARCH_PAGE_TABLE_SYNC_MASK 0
> -#endif
> -
> -/*
> - * There is no default implementation for arch_sync_kernel_mappings(). It is
> - * relied upon the compiler to optimize calls out if ARCH_PAGE_TABLE_SYNC_MASK
> - * is 0.
> - */
> -void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
> -
>  /*
>   *	Lowlevel-APIs (not for driver use!)
>   */
> -- 
> 2.43.0
> 

-- 
Sincerely yours,
Mike.