Re: [PATCH 01/15] mm: various small mmap_prepare cleanups

["Lorenzo Stoakes (Oracle)" <ljs@kernel.org>]

On Sun, Mar 15, 2026 at 04:06:48PM -0700, Suren Baghdasaryan wrote:
> > > --- a/include/linux/mm.h
> > > +++ b/include/linux/mm.h
> > > @@ -4116,10 +4116,10 @@ static inline void mmap_action_ioremap_full(struct vm_area_desc *desc,
> > >         mmap_action_ioremap(desc, desc->start, start_pfn, vma_desc_size(desc));
> > >  }
> > >
> > > -void mmap_action_prepare(struct mmap_action *action,
> > > -                        struct vm_area_desc *desc);
> > > -int mmap_action_complete(struct mmap_action *action,
> > > -                        struct vm_area_struct *vma);
> > > +int mmap_action_prepare(struct vm_area_desc *desc,
> > > +                       struct mmap_action *action);
> > > +int mmap_action_complete(struct vm_area_struct *vma,
> > > +                        struct mmap_action *action);
> > >
> > >  /* Look up the first VMA which exactly match the interval vm_start ... vm_end */
> > >  static inline struct vm_area_struct *find_exact_vma(struct mm_struct *mm,
> > > diff --git a/mm/internal.h b/mm/internal.h
> > > index 95b583e7e4f7..7bfa85b5e78b 100644
> > > --- a/mm/internal.h
> > > +++ b/mm/internal.h
> > > @@ -1775,26 +1775,32 @@ int walk_page_range_debug(struct mm_struct *mm, unsigned long start,
> > >  void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm);
> > >  int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm);
> > >
> > > -void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn);
> > > -int remap_pfn_range_complete(struct vm_area_struct *vma, unsigned long addr,
> > > -               unsigned long pfn, unsigned long size, pgprot_t pgprot);
> > > +int remap_pfn_range_prepare(struct vm_area_desc *desc,
> > > +                           struct mmap_action *action);
> > > +int remap_pfn_range_complete(struct vm_area_struct *vma,
> > > +                            struct mmap_action *action);
> > >
> > > -static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc,
> > > -               unsigned long orig_pfn, unsigned long size)
> > > +static inline int io_remap_pfn_range_prepare(struct vm_area_desc *desc,
> > > +                                            struct mmap_action *action)
> > >  {
> > > +       const unsigned long orig_pfn = action->remap.start_pfn;
> > > +       const unsigned long size = action->remap.size;
> > >         const unsigned long pfn = io_remap_pfn_range_pfn(orig_pfn, size);
> > >
> > > -       return remap_pfn_range_prepare(desc, pfn);
> > > +       action->remap.start_pfn = pfn;
> > > +       return remap_pfn_range_prepare(desc, action);
> > >  }
> > >
> > >  static inline int io_remap_pfn_range_complete(struct vm_area_struct *vma,
> > > -               unsigned long addr, unsigned long orig_pfn, unsigned long size,
> > > -               pgprot_t orig_prot)
> > > +                                             struct mmap_action *action)
> > >  {
> > > -       const unsigned long pfn = io_remap_pfn_range_pfn(orig_pfn, size);
> > > -       const pgprot_t prot = pgprot_decrypted(orig_prot);
> > > +       const unsigned long size = action->remap.size;
> > > +       const unsigned long orig_pfn = action->remap.start_pfn;
> > > +       const pgprot_t orig_prot = vma->vm_page_prot;
> > >
> > > -       return remap_pfn_range_complete(vma, addr, pfn, size, prot);
> > > +       action->remap.pgprot = pgprot_decrypted(orig_prot);
>
> I'm guessing it doesn't really matter but after this change
> action->remap.pgprot will store the decrypted value while before this
> change it was kept the way mmap_prepare() originally set it. We pass
> the action structure later to mmap_actpion_finish() but it does not use
> action->remap.pgprot, so this probably doesn't matter.

Yeah it doesn't really matter either way.

Cheers, Lorenzo