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

[Suren Baghdasaryan <surenb@google.com>]

On Mon, Mar 16, 2026 at 7:44 AM Lorenzo Stoakes (Oracle) <ljs@kernel.org> wrote:
>
> On Sun, Mar 15, 2026 at 03:56:54PM -0700, Suren Baghdasaryan wrote:
> > On Thu, Mar 12, 2026 at 1:27 PM Lorenzo Stoakes (Oracle) <ljs@kernel.org> wrote:
> > >
> > > Rather than passing arbitrary fields, pass an mmap_action field directly to
> > > mmap prepare and complete helpers to put all the action-specific logic in
> > > the function actually doing the work.
> > >
> > > Additionally, allow mmap prepare functions to return an error so we can
> > > error out as soon as possible if there is something logically incorrect in
> > > the input.
> > >
> > > Update remap_pfn_range_prepare() to properly check the input range for the
> > > CoW case.
> >
> > By "properly check" do you mean the replacement of desc->start and
> > desc->end with action->remap.start and action->remap.start +
> > action->remap.size when calling get_remap_pgoff() from
> > remap_pfn_range_prepare()?
> >
> > >
> > > While we're here, make remap_pfn_range_prepare_vma() a little neater, and
> > > pass mmap_action directly to call_action_complete().
> > >
> > > Then, update compat_vma_mmap() to perform its logic directly, as
> > > __compat_vma_map() is not used by anything so we don't need to export it.
> >
> > Not directly related to this patch but while reviewing, I was also
> > checking vma locking rules in this mmap_prepare() + mmap() sequence
> > and I noticed that the new VMA flag modification functions like
> > vma_set_flags_mask() do assert vma_assert_locked(vma). It would be
>
> Do NOT? :)

Right :)

>
> I don't think it'd work, because in some cases you're setting flags for a
> VMA that is not yet inserted in the tree, etc.

Ah, I see. So, there won't be something similar to vm_flags_init()
that sets vm_flags before the VMA is added to the tree...
I'm a bit paranoid about catching the cases when a VMA is changed
without being locked. Maybe we can add such assert if
vma_is_attached() later. But this is really out of scope of this
patchset, so let's discuss it later. Sorry for the noise.

>
> I don't think it's hugely useful to split out these functions in some way
> in the way the vm_flags_*() stuff is split so we assert sometimes, not
> others.
>
> I'd rather keep this as clean an interface as possible.

Ack.

>
> In any case the majority of cases where flags are being set are not on the
> VMA, so really only core code, that would likely otherwise assert when it
> needs to, would already be asserting.
>
> The cases where drivers will do it, all of them will be using
> vma_desc_set_flags() etc.

That was my biggest worry as drivers might do some VMA modifications
without proper locking but you are right, with mmap_prepare() that
stops being a problem.

>
> > useful to add these but as a separate change. I will add it to my todo
> > list.
>
> So I don't think it'd be generally useful at this time.
>
> >
> > >
> > > Also update compat_vma_mmap() to use vfs_mmap_prepare() rather than calling
> > > the mmap_prepare op directly.
> > >
> > > Finally, update the VMA userland tests to reflect the changes.
> > >
> > > Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
> > > ---
> > >  include/linux/fs.h                |   2 -
> > >  include/linux/mm.h                |   8 +--
> > >  mm/internal.h                     |  28 +++++---
> > >  mm/memory.c                       |  45 +++++++-----
> > >  mm/util.c                         | 112 +++++++++++++-----------------
> > >  mm/vma.c                          |  21 +++---
> > >  tools/testing/vma/include/dup.h   |   9 ++-
> > >  tools/testing/vma/include/stubs.h |   9 +--
> > >  8 files changed, 123 insertions(+), 111 deletions(-)
> > >
> > > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > > index 8b3dd145b25e..a2628a12bd2b 100644
> > > --- a/include/linux/fs.h
> > > +++ b/include/linux/fs.h
> > > @@ -2058,8 +2058,6 @@ static inline bool can_mmap_file(struct file *file)
> > >         return true;
> > >  }
> > >
> > > -int __compat_vma_mmap(const struct file_operations *f_op,
> > > -               struct file *file, struct vm_area_struct *vma);
> > >  int compat_vma_mmap(struct file *file, struct vm_area_struct *vma);
> > >
> > >  static inline int vfs_mmap(struct file *file, struct vm_area_struct *vma)
> > > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > > index 4c4fd55fc823..cc5960a84382 100644
> > > --- 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);
> > > +       action->remap.start_pfn  = io_remap_pfn_range_pfn(orig_pfn, size);
> > > +       return remap_pfn_range_complete(vma, action);
> > >  }
> > >
> > >  #ifdef CONFIG_MMU_NOTIFIER
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index 6aa0ea4af1fc..364fa8a45360 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -3099,26 +3099,34 @@ static int do_remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
> > >  }
> > >  #endif
> > >
> > > -void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn)
> > > +int remap_pfn_range_prepare(struct vm_area_desc *desc,
> > > +                           struct mmap_action *action)
> > >  {
> > > -       /*
> > > -        * We set addr=VMA start, end=VMA end here, so this won't fail, but we
> > > -        * check it again on complete and will fail there if specified addr is
> > > -        * invalid.
> > > -        */
> > > -       get_remap_pgoff(vma_desc_is_cow_mapping(desc), desc->start, desc->end,
> > > -                       desc->start, desc->end, pfn, &desc->pgoff);
> > > +       const unsigned long start = action->remap.start;
> > > +       const unsigned long end = start + action->remap.size;
> > > +       const unsigned long pfn = action->remap.start_pfn;
> > > +       const bool is_cow = vma_desc_is_cow_mapping(desc);
> >
> > I was trying to figure out who sets action->remap.start and
> > action->remap.size and if they somehow guaranteed to be always equal
> > to desc->start and (desc->end - desc->start). My understanding is that
> > action->remap.start and action->remap.size are set by
> > f_op->mmap_prepare() but I'm not sure if they are always the same as
> > desc->start and (desc->end - desc->start) and if so, how do we enforce
> > that.
>
> They are set, and they might not always be the same, because the existing
> implementation does not set them the same.
>
> Once I've completed the change, I can check to ensure that nobody is doing
> anything crazy with this.
>
> I also plan to add specific discontiguous range handlers to handle the
> cases where drivers wish to map that way.
>
> In fact, I already implemented it (and DMA coherent stuff) but stripped it
> out the series for now for time (the original series was ~27 patches :) as
> I want to test that more etc.
>
> Users have access to mmap_action_remap_full() to specify that they want to
> remap the full range.

Got it. IOW [action->remap.start,
action->remap.start+action->remap.size] should be equal or contained
within [desc->start, desc->end] range.

>
> >
> > > +       int err;
> > > +
> > > +       err = get_remap_pgoff(is_cow, start, end, desc->start, desc->end, pfn,
> > > +                             &desc->pgoff);
> > > +       if (err)
> > > +               return err;
> > > +
> > >         vma_desc_set_flags_mask(desc, VMA_REMAP_FLAGS);
> > > +       return 0;
> > >  }
> > >
> > > -static int remap_pfn_range_prepare_vma(struct vm_area_struct *vma, unsigned long addr,
> > > -               unsigned long pfn, unsigned long size)
> > > +static int remap_pfn_range_prepare_vma(struct vm_area_struct *vma,
> > > +                                      unsigned long addr, unsigned long pfn,
> > > +                                      unsigned long size)
> > >  {
> > > -       unsigned long end = addr + PAGE_ALIGN(size);
> > > +       const unsigned long end = addr + PAGE_ALIGN(size);
> > > +       const bool is_cow = is_cow_mapping(vma->vm_flags);
> > >         int err;
> > >
> > > -       err = get_remap_pgoff(is_cow_mapping(vma->vm_flags), addr, end,
> > > -                             vma->vm_start, vma->vm_end, pfn, &vma->vm_pgoff);
> > > +       err = get_remap_pgoff(is_cow, addr, end, vma->vm_start, vma->vm_end,
> > > +                             pfn, &vma->vm_pgoff);
> > >         if (err)
> > >                 return err;
> > >
> > > @@ -3151,10 +3159,15 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
> > >  }
> > >  EXPORT_SYMBOL(remap_pfn_range);
> > >
> > > -int remap_pfn_range_complete(struct vm_area_struct *vma, unsigned long addr,
> > > -               unsigned long pfn, unsigned long size, pgprot_t prot)
> > > +int remap_pfn_range_complete(struct vm_area_struct *vma,
> > > +                            struct mmap_action *action)
> > >  {
> > > -       return do_remap_pfn_range(vma, addr, pfn, size, prot);
> > > +       const unsigned long start = action->remap.start;
> > > +       const unsigned long pfn = action->remap.start_pfn;
> > > +       const unsigned long size = action->remap.size;
> > > +       const pgprot_t prot = action->remap.pgprot;
> > > +
> > > +       return do_remap_pfn_range(vma, start, pfn, size, prot);
> > >  }
> > >
> > >  /**
> > > diff --git a/mm/util.c b/mm/util.c
> > > index ce7ae80047cf..dba1191725b6 100644
> > > --- a/mm/util.c
> > > +++ b/mm/util.c
> > > @@ -1163,43 +1163,6 @@ void flush_dcache_folio(struct folio *folio)
> > >  EXPORT_SYMBOL(flush_dcache_folio);
> > >  #endif
> > >
> > > -/**
> > > - * __compat_vma_mmap() - See description for compat_vma_mmap()
> > > - * for details. This is the same operation, only with a specific file operations
> > > - * struct which may or may not be the same as vma->vm_file->f_op.
> > > - * @f_op: The file operations whose .mmap_prepare() hook is specified.
> > > - * @file: The file which backs or will back the mapping.
> > > - * @vma: The VMA to apply the .mmap_prepare() hook to.
> > > - * Returns: 0 on success or error.
> > > - */
> > > -int __compat_vma_mmap(const struct file_operations *f_op,
> > > -               struct file *file, struct vm_area_struct *vma)
> > > -{
> > > -       struct vm_area_desc desc = {
> > > -               .mm = vma->vm_mm,
> > > -               .file = file,
> > > -               .start = vma->vm_start,
> > > -               .end = vma->vm_end,
> > > -
> > > -               .pgoff = vma->vm_pgoff,
> > > -               .vm_file = vma->vm_file,
> > > -               .vma_flags = vma->flags,
> > > -               .page_prot = vma->vm_page_prot,
> > > -
> > > -               .action.type = MMAP_NOTHING, /* Default */
> > > -       };
> > > -       int err;
> > > -
> > > -       err = f_op->mmap_prepare(&desc);
> > > -       if (err)
> > > -               return err;
> > > -
> > > -       mmap_action_prepare(&desc.action, &desc);
> > > -       set_vma_from_desc(vma, &desc);
> > > -       return mmap_action_complete(&desc.action, vma);
> > > -}
> > > -EXPORT_SYMBOL(__compat_vma_mmap);
> > > -
> > >  /**
> > >   * compat_vma_mmap() - Apply the file's .mmap_prepare() hook to an
> > >   * existing VMA and execute any requested actions.
> > > @@ -1228,7 +1191,31 @@ EXPORT_SYMBOL(__compat_vma_mmap);
> > >   */
> > >  int compat_vma_mmap(struct file *file, struct vm_area_struct *vma)
> > >  {
> > > -       return __compat_vma_mmap(file->f_op, file, vma);
> > > +       struct vm_area_desc desc = {
> > > +               .mm = vma->vm_mm,
> > > +               .file = file,
> > > +               .start = vma->vm_start,
> > > +               .end = vma->vm_end,
> > > +
> > > +               .pgoff = vma->vm_pgoff,
> > > +               .vm_file = vma->vm_file,
> > > +               .vma_flags = vma->flags,
> > > +               .page_prot = vma->vm_page_prot,
> > > +
> > > +               .action.type = MMAP_NOTHING, /* Default */
> > > +       };
> > > +       int err;
> > > +
> > > +       err = vfs_mmap_prepare(file, &desc);
> > > +       if (err)
> > > +               return err;
> > > +
> > > +       err = mmap_action_prepare(&desc, &desc.action);
> > > +       if (err)
> > > +               return err;
> > > +
> > > +       set_vma_from_desc(vma, &desc);
> > > +       return mmap_action_complete(vma, &desc.action);
> > >  }
> > >  EXPORT_SYMBOL(compat_vma_mmap);
> > >
> > > @@ -1320,8 +1307,8 @@ void snapshot_page(struct page_snapshot *ps, const struct page *page)
> > >         }
> > >  }
> > >
> > > -static int mmap_action_finish(struct mmap_action *action,
> > > -               const struct vm_area_struct *vma, int err)
> > > +static int mmap_action_finish(struct vm_area_struct *vma,
> > > +                             struct mmap_action *action, int err)
> > >  {
> > >         /*
> > >          * If an error occurs, unmap the VMA altogether and return an error. We
> > > @@ -1355,35 +1342,36 @@ static int mmap_action_finish(struct mmap_action *action,
> > >   * action which need to be performed.
> > >   * @desc: The VMA descriptor to prepare for @action.
> > >   * @action: The action to perform.
> > > + *
> > > + * Returns: 0 on success, otherwise error.
> > >   */
> > > -void mmap_action_prepare(struct mmap_action *action,
> > > -                        struct vm_area_desc *desc)
> > > +int mmap_action_prepare(struct vm_area_desc *desc,
> > > +                       struct mmap_action *action)
> >
> > Any reason you are swapping the arguments?
>
> For consistency with other functions to be added.
>
> > It also looks like we always call mmap_action_prepare() with action ==
> > desc->action, like this: mmap_action_prepare(&desc.action, &desc). Why
> > don't we eliminate the action parameter altogether and use desc.action
> > from inside the function?
>
> I think in previous iterations I thought about overriding one action with
> another and wanted to keep that flexibility, but then have never done that
> in practice.
>
> So probably I can just drop that yes, will try it on respin.

Thanks.

>
> >
> > > +
> >
> > extra new line.
>
> Ack will fix

Thanks.

>
> >
> > >  {
> > >         switch (action->type) {
> > >         case MMAP_NOTHING:
> > > -               break;
> > > +               return 0;
> > >         case MMAP_REMAP_PFN:
> > > -               remap_pfn_range_prepare(desc, action->remap.start_pfn);
> > > -               break;
> > > +               return remap_pfn_range_prepare(desc, action);
> > >         case MMAP_IO_REMAP_PFN:
> > > -               io_remap_pfn_range_prepare(desc, action->remap.start_pfn,
> > > -                                          action->remap.size);
> > > -               break;
> > > +               return io_remap_pfn_range_prepare(desc, action);
> > >         }
> > >  }
> > >  EXPORT_SYMBOL(mmap_action_prepare);
> > >
> > >  /**
> > >   * mmap_action_complete - Execute VMA descriptor action.
> > > - * @action: The action to perform.
> > >   * @vma: The VMA to perform the action upon.
> > > + * @action: The action to perform.
> > >   *
>
> > >   * Similar to mmap_action_prepare().
> > >   *
> > >   * Return: 0 on success, or error, at which point the VMA will be unmapped.
> > >   */
> > > -int mmap_action_complete(struct mmap_action *action,
> > > -                        struct vm_area_struct *vma)
> > > +int mmap_action_complete(struct vm_area_struct *vma,
> > > +                        struct mmap_action *action)
> > > +
> > >  {
> > >         int err = 0;
> > >
> > > @@ -1391,23 +1379,19 @@ int mmap_action_complete(struct mmap_action *action,
> > >         case MMAP_NOTHING:
> > >                 break;
> > >         case MMAP_REMAP_PFN:
> > > -               err = remap_pfn_range_complete(vma, action->remap.start,
> > > -                               action->remap.start_pfn, action->remap.size,
> > > -                               action->remap.pgprot);
> > > +               err = remap_pfn_range_complete(vma, action);
> > >                 break;
> > >         case MMAP_IO_REMAP_PFN:
> > > -               err = io_remap_pfn_range_complete(vma, action->remap.start,
> > > -                               action->remap.start_pfn, action->remap.size,
> > > -                               action->remap.pgprot);
> > > +               err = io_remap_pfn_range_complete(vma, action);
> > >                 break;
> > >         }
> > >
> > > -       return mmap_action_finish(action, vma, err);
> > > +       return mmap_action_finish(vma, action, err);
> > >  }
> > >  EXPORT_SYMBOL(mmap_action_complete);
> > >  #else
> > > -void mmap_action_prepare(struct mmap_action *action,
> > > -                       struct vm_area_desc *desc)
> > > +int mmap_action_prepare(struct vm_area_desc *desc,
> > > +                       struct mmap_action *action)
> > >  {
> > >         switch (action->type) {
> > >         case MMAP_NOTHING:
> > > @@ -1417,11 +1401,13 @@ void mmap_action_prepare(struct mmap_action *action,
> > >                 WARN_ON_ONCE(1); /* nommu cannot handle these. */
> > >                 break;
> > >         }
> > > +
> > > +       return 0;
> > >  }
> > >  EXPORT_SYMBOL(mmap_action_prepare);
> > >
> > > -int mmap_action_complete(struct mmap_action *action,
> > > -                       struct vm_area_struct *vma)
> > > +int mmap_action_complete(struct vm_area_struct *vma,
> > > +                        struct mmap_action *action)
> > >  {
> > >         int err = 0;
> > >
> > > @@ -1436,7 +1422,7 @@ int mmap_action_complete(struct mmap_action *action,
> > >                 break;
> > >         }
> > >
> > > -       return mmap_action_finish(action, vma, err);
> > > +       return mmap_action_finish(vma, action, err);
> > >  }
> > >  EXPORT_SYMBOL(mmap_action_complete);
> > >  #endif
> > > diff --git a/mm/vma.c b/mm/vma.c
> > > index be64f781a3aa..054cf1d262fb 100644
> > > --- a/mm/vma.c
> > > +++ b/mm/vma.c
> > > @@ -2613,15 +2613,19 @@ static void __mmap_complete(struct mmap_state *map, struct vm_area_struct *vma)
> > >         vma_set_page_prot(vma);
> > >  }
> > >
> > > -static void call_action_prepare(struct mmap_state *map,
> > > -                               struct vm_area_desc *desc)
> > > +static int call_action_prepare(struct mmap_state *map,
> > > +                              struct vm_area_desc *desc)
> > >  {
> > >         struct mmap_action *action = &desc->action;
> > > +       int err;
> > >
> > > -       mmap_action_prepare(action, desc);
> > > +       err = mmap_action_prepare(desc, action);
> > > +       if (err)
> > > +               return err;
> > >
> > >         if (action->hide_from_rmap_until_complete)
> > >                 map->hold_file_rmap_lock = true;
> > > +       return 0;
> > >  }
> > >
> > >  /*
> > > @@ -2645,7 +2649,9 @@ static int call_mmap_prepare(struct mmap_state *map,
> > >         if (err)
> > >                 return err;
> > >
> > > -       call_action_prepare(map, desc);
> > > +       err = call_action_prepare(map, desc);
> > > +       if (err)
> > > +               return err;
> > >
> > >         /* Update fields permitted to be changed. */
> > >         map->pgoff = desc->pgoff;
> > > @@ -2700,13 +2706,12 @@ static bool can_set_ksm_flags_early(struct mmap_state *map)
> > >  }
> > >
> > >  static int call_action_complete(struct mmap_state *map,
> > > -                               struct vm_area_desc *desc,
> > > +                               struct mmap_action *action,
> > >                                 struct vm_area_struct *vma)
> > >  {
> > > -       struct mmap_action *action = &desc->action;
> > >         int ret;
> > >
> > > -       ret = mmap_action_complete(action, vma);
> > > +       ret = mmap_action_complete(vma, action);
> > >
> > >         /* If we held the file rmap we need to release it. */
> > >         if (map->hold_file_rmap_lock) {
> > > @@ -2768,7 +2773,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr,
> > >         __mmap_complete(&map, vma);
> > >
> > >         if (have_mmap_prepare && allocated_new) {
> > > -               error = call_action_complete(&map, &desc, vma);
> > > +               error = call_action_complete(&map, &desc.action, vma);
> > >
> > >                 if (error)
> > >                         return error;
> > > diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h
> > > index 5eb313beb43d..908beb263307 100644
> > > --- a/tools/testing/vma/include/dup.h
> > > +++ b/tools/testing/vma/include/dup.h
> > > @@ -1106,7 +1106,7 @@ static inline int __compat_vma_mmap(const struct file_operations *f_op,
> > >
> > >                 .pgoff = vma->vm_pgoff,
> > >                 .vm_file = vma->vm_file,
> > > -               .vm_flags = vma->vm_flags,
> > > +               .vma_flags = vma->flags,
> > >                 .page_prot = vma->vm_page_prot,
> > >
> > >                 .action.type = MMAP_NOTHING, /* Default */
> > > @@ -1117,9 +1117,12 @@ static inline int __compat_vma_mmap(const struct file_operations *f_op,
> > >         if (err)
> > >                 return err;
> > >
> > > -       mmap_action_prepare(&desc.action, &desc);
> > > +       err = mmap_action_prepare(&desc, &desc.action);
> > > +       if (err)
> > > +               return err;
> > > +
> > >         set_vma_from_desc(vma, &desc);
> > > -       return mmap_action_complete(&desc.action, vma);
> > > +       return mmap_action_complete(vma, &desc.action);
> > >  }
> > >
> > >  static inline int compat_vma_mmap(struct file *file,
> > > diff --git a/tools/testing/vma/include/stubs.h b/tools/testing/vma/include/stubs.h
> > > index 947a3a0c2566..76c4b668bc62 100644
> > > --- a/tools/testing/vma/include/stubs.h
> > > +++ b/tools/testing/vma/include/stubs.h
> > > @@ -81,13 +81,14 @@ static inline void free_anon_vma_name(struct vm_area_struct *vma)
> > >  {
> > >  }
> > >
> > > -static inline void mmap_action_prepare(struct mmap_action *action,
> > > -                                          struct vm_area_desc *desc)
> > > +static inline int mmap_action_prepare(struct vm_area_desc *desc,
> > > +                                     struct mmap_action *action)
> > >  {
> > > +       return 0;
> > >  }
> > >
> > > -static inline int mmap_action_complete(struct mmap_action *action,
> > > -                                          struct vm_area_struct *vma)
> > > +static inline int mmap_action_complete(struct vm_area_struct *vma,
> > > +                                      struct mmap_action *action)
> > >  {
> > >         return 0;
> > >  }
> > > --
> > > 2.53.0
> > >