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

Mike Rapoport
2025-08-11T08:06:09Z

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@vger.kernel.org>
> Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
> Signed-off-by: Harry Yoo <harry.yoo@oracle.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@kernel.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.