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

[Uladzislau Rezki]

On Mon, Aug 11, 2025 at 11:05:51AM +0300, Mike Rapoport wrote:
> 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@xxxxxxxxxxxxxxx>
> > Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
> > Signed-off-by: Harry Yoo <harry.yoo@xxxxxxxxxx>
> > ---
> >  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@xxxxxxxxxx>
> 
> > + * 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
> > 
> 
LGTM,

Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>

--
Uladzislau Rezki