LinuxTV Patchwork [v2,1/9] mm: Introduce new vm_insert_range API

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Submitter Souptick Joarder
Date Dec. 2, 2018, 6:19 a.m.
Message ID <20181202061944.GA3094@jordon-HP-15-Notebook-PC>
Download mbox | patch
Permalink /patch/53242/
State Superseded
Headers show

Comments

Souptick Joarder - Dec. 2, 2018, 6:19 a.m.
Previouly drivers have their own way of mapping range of
kernel pages/memory into user vma and this was done by
invoking vm_insert_page() within a loop.

As this pattern is common across different drivers, it can
be generalized by creating a new function and use it across
the drivers.

vm_insert_range is the new API which will be used to map a
range of kernel memory/pages to user vma.

This API is tested by Heiko for Rockchip drm driver, on rk3188,
rk3288, rk3328 and rk3399 with graphics.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
---
 include/linux/mm_types.h |  3 +++
 mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
 mm/nommu.c               |  7 +++++++
 3 files changed, 48 insertions(+)
Mike Rapoport - Dec. 2, 2018, 11:13 a.m.
On Sun, Dec 02, 2018 at 11:49:44AM +0530, Souptick Joarder wrote:
> Previouly drivers have their own way of mapping range of
> kernel pages/memory into user vma and this was done by
> invoking vm_insert_page() within a loop.
> 
> As this pattern is common across different drivers, it can
> be generalized by creating a new function and use it across
> the drivers.
> 
> vm_insert_range is the new API which will be used to map a
> range of kernel memory/pages to user vma.
> 
> This API is tested by Heiko for Rockchip drm driver, on rk3188,
> rk3288, rk3328 and rk3399 with graphics.
> 
> Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> Reviewed-by: Matthew Wilcox <willy@infradead.org>
> Tested-by: Heiko Stuebner <heiko@sntech.de>
> ---
>  include/linux/mm_types.h |  3 +++
>  mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
>  mm/nommu.c               |  7 +++++++
>  3 files changed, 48 insertions(+)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 5ed8f62..15ae24f 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -523,6 +523,9 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
>  extern void tlb_finish_mmu(struct mmu_gather *tlb,
>  				unsigned long start, unsigned long end);
> 
> +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> +			struct page **pages, unsigned long page_count);
> +

This seem to belong to include/linux/mm.h, near vm_insert_page()

>  static inline void init_tlb_flush_pending(struct mm_struct *mm)
>  {
>  	atomic_set(&mm->tlb_flush_pending, 0);
> diff --git a/mm/memory.c b/mm/memory.c
> index 15c417e..84ea46c 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
>  }
> 
>  /**
> + * vm_insert_range - insert range of kernel pages into user vma
> + * @vma: user vma to map to
> + * @addr: target user address of this page
> + * @pages: pointer to array of source kernel pages
> + * @page_count: number of pages need to insert into user vma
> + *
> + * This allows drivers to insert range of kernel pages they've allocated
> + * into a user vma. This is a generic function which drivers can use
> + * rather than using their own way of mapping range of kernel pages into
> + * user vma.
> + *
> + * If we fail to insert any page into the vma, the function will return
> + * immediately leaving any previously-inserted pages present.  Callers
> + * from the mmap handler may immediately return the error as their caller
> + * will destroy the vma, removing any successfully-inserted pages. Other
> + * callers should make their own arrangements for calling unmap_region().
> + *
> + * Context: Process context. Called by mmap handlers.
> + * Return: 0 on success and error code otherwise
> + */
> +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> +			struct page **pages, unsigned long page_count)
> +{
> +	unsigned long uaddr = addr;
> +	int ret = 0, i;
> +
> +	for (i = 0; i < page_count; i++) {
> +		ret = vm_insert_page(vma, uaddr, pages[i]);
> +		if (ret < 0)
> +			return ret;
> +		uaddr += PAGE_SIZE;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(vm_insert_range);
> +
> +/**
>   * vm_insert_page - insert single page into user vma
>   * @vma: user vma to map to
>   * @addr: target user address of this page
> diff --git a/mm/nommu.c b/mm/nommu.c
> index 749276b..d6ef5c7 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
>  }
>  EXPORT_SYMBOL(vm_insert_page);
> 
> +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> +			struct page **pages, unsigned long page_count)
> +{
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL(vm_insert_range);
> +
>  /*
>   *  sys_brk() for the most part doesn't need the global kernel
>   *  lock, except when an application is doing something nasty
> -- 
> 1.9.1
>
Souptick Joarder - Dec. 3, 2018, 4:21 a.m.
Hi Mike,

On Sun, Dec 2, 2018 at 4:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
>
> On Sun, Dec 02, 2018 at 11:49:44AM +0530, Souptick Joarder wrote:
> > Previouly drivers have their own way of mapping range of
> > kernel pages/memory into user vma and this was done by
> > invoking vm_insert_page() within a loop.
> >
> > As this pattern is common across different drivers, it can
> > be generalized by creating a new function and use it across
> > the drivers.
> >
> > vm_insert_range is the new API which will be used to map a
> > range of kernel memory/pages to user vma.
> >
> > This API is tested by Heiko for Rockchip drm driver, on rk3188,
> > rk3288, rk3328 and rk3399 with graphics.
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > Reviewed-by: Matthew Wilcox <willy@infradead.org>
> > Tested-by: Heiko Stuebner <heiko@sntech.de>
> > ---
> >  include/linux/mm_types.h |  3 +++
> >  mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
> >  mm/nommu.c               |  7 +++++++
> >  3 files changed, 48 insertions(+)
> >
> > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > index 5ed8f62..15ae24f 100644
> > --- a/include/linux/mm_types.h
> > +++ b/include/linux/mm_types.h
> > @@ -523,6 +523,9 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
> >  extern void tlb_finish_mmu(struct mmu_gather *tlb,
> >                               unsigned long start, unsigned long end);
> >
> > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > +                     struct page **pages, unsigned long page_count);
> > +
>
> This seem to belong to include/linux/mm.h, near vm_insert_page()

Ok, I will change it. Apart from this change does it looks good ?

>
> >  static inline void init_tlb_flush_pending(struct mm_struct *mm)
> >  {
> >       atomic_set(&mm->tlb_flush_pending, 0);
> > diff --git a/mm/memory.c b/mm/memory.c
> > index 15c417e..84ea46c 100644
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
> >  }
> >
> >  /**
> > + * vm_insert_range - insert range of kernel pages into user vma
> > + * @vma: user vma to map to
> > + * @addr: target user address of this page
> > + * @pages: pointer to array of source kernel pages
> > + * @page_count: number of pages need to insert into user vma
> > + *
> > + * This allows drivers to insert range of kernel pages they've allocated
> > + * into a user vma. This is a generic function which drivers can use
> > + * rather than using their own way of mapping range of kernel pages into
> > + * user vma.
> > + *
> > + * If we fail to insert any page into the vma, the function will return
> > + * immediately leaving any previously-inserted pages present.  Callers
> > + * from the mmap handler may immediately return the error as their caller
> > + * will destroy the vma, removing any successfully-inserted pages. Other
> > + * callers should make their own arrangements for calling unmap_region().
> > + *
> > + * Context: Process context. Called by mmap handlers.
> > + * Return: 0 on success and error code otherwise
> > + */
> > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > +                     struct page **pages, unsigned long page_count)
> > +{
> > +     unsigned long uaddr = addr;
> > +     int ret = 0, i;
> > +
> > +     for (i = 0; i < page_count; i++) {
> > +             ret = vm_insert_page(vma, uaddr, pages[i]);
> > +             if (ret < 0)
> > +                     return ret;
> > +             uaddr += PAGE_SIZE;
> > +     }
> > +
> > +     return ret;
> > +}
> > +EXPORT_SYMBOL(vm_insert_range);
> > +
> > +/**
> >   * vm_insert_page - insert single page into user vma
> >   * @vma: user vma to map to
> >   * @addr: target user address of this page
> > diff --git a/mm/nommu.c b/mm/nommu.c
> > index 749276b..d6ef5c7 100644
> > --- a/mm/nommu.c
> > +++ b/mm/nommu.c
> > @@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
> >  }
> >  EXPORT_SYMBOL(vm_insert_page);
> >
> > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > +                     struct page **pages, unsigned long page_count)
> > +{
> > +     return -EINVAL;
> > +}
> > +EXPORT_SYMBOL(vm_insert_range);
> > +
> >  /*
> >   *  sys_brk() for the most part doesn't need the global kernel
> >   *  lock, except when an application is doing something nasty
> > --
> > 1.9.1
> >
>
> --
> Sincerely yours,
> Mike.
>
Mike Rapoport - Dec. 3, 2018, 6:22 a.m.
On Mon, Dec 03, 2018 at 09:51:45AM +0530, Souptick Joarder wrote:
> Hi Mike,
> 
> On Sun, Dec 2, 2018 at 4:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
> >
> > On Sun, Dec 02, 2018 at 11:49:44AM +0530, Souptick Joarder wrote:
> > > Previouly drivers have their own way of mapping range of
> > > kernel pages/memory into user vma and this was done by
> > > invoking vm_insert_page() within a loop.
> > >
> > > As this pattern is common across different drivers, it can
> > > be generalized by creating a new function and use it across
> > > the drivers.
> > >
> > > vm_insert_range is the new API which will be used to map a
> > > range of kernel memory/pages to user vma.
> > >
> > > This API is tested by Heiko for Rockchip drm driver, on rk3188,
> > > rk3288, rk3328 and rk3399 with graphics.
> > >
> > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > > Reviewed-by: Matthew Wilcox <willy@infradead.org>
> > > Tested-by: Heiko Stuebner <heiko@sntech.de>
> > > ---
> > >  include/linux/mm_types.h |  3 +++
> > >  mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
> > >  mm/nommu.c               |  7 +++++++
> > >  3 files changed, 48 insertions(+)
> > >
> > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > > index 5ed8f62..15ae24f 100644
> > > --- a/include/linux/mm_types.h
> > > +++ b/include/linux/mm_types.h
> > > @@ -523,6 +523,9 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
> > >  extern void tlb_finish_mmu(struct mmu_gather *tlb,
> > >                               unsigned long start, unsigned long end);
> > >
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count);
> > > +
> >
> > This seem to belong to include/linux/mm.h, near vm_insert_page()
> 
> Ok, I will change it. Apart from this change does it looks good ?

With this change you can add

Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
 
> >
> > >  static inline void init_tlb_flush_pending(struct mm_struct *mm)
> > >  {
> > >       atomic_set(&mm->tlb_flush_pending, 0);
> > > diff --git a/mm/memory.c b/mm/memory.c
> > > index 15c417e..84ea46c 100644
> > > --- a/mm/memory.c
> > > +++ b/mm/memory.c
> > > @@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
> > >  }
> > >
> > >  /**
> > > + * vm_insert_range - insert range of kernel pages into user vma
> > > + * @vma: user vma to map to
> > > + * @addr: target user address of this page
> > > + * @pages: pointer to array of source kernel pages
> > > + * @page_count: number of pages need to insert into user vma
> > > + *
> > > + * This allows drivers to insert range of kernel pages they've allocated
> > > + * into a user vma. This is a generic function which drivers can use
> > > + * rather than using their own way of mapping range of kernel pages into
> > > + * user vma.
> > > + *
> > > + * If we fail to insert any page into the vma, the function will return
> > > + * immediately leaving any previously-inserted pages present.  Callers
> > > + * from the mmap handler may immediately return the error as their caller
> > > + * will destroy the vma, removing any successfully-inserted pages. Other
> > > + * callers should make their own arrangements for calling unmap_region().
> > > + *
> > > + * Context: Process context. Called by mmap handlers.
> > > + * Return: 0 on success and error code otherwise
> > > + */
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count)
> > > +{
> > > +     unsigned long uaddr = addr;
> > > +     int ret = 0, i;
> > > +
> > > +     for (i = 0; i < page_count; i++) {
> > > +             ret = vm_insert_page(vma, uaddr, pages[i]);
> > > +             if (ret < 0)
> > > +                     return ret;
> > > +             uaddr += PAGE_SIZE;
> > > +     }
> > > +
> > > +     return ret;
> > > +}
> > > +EXPORT_SYMBOL(vm_insert_range);
> > > +
> > > +/**
> > >   * vm_insert_page - insert single page into user vma
> > >   * @vma: user vma to map to
> > >   * @addr: target user address of this page
> > > diff --git a/mm/nommu.c b/mm/nommu.c
> > > index 749276b..d6ef5c7 100644
> > > --- a/mm/nommu.c
> > > +++ b/mm/nommu.c
> > > @@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
> > >  }
> > >  EXPORT_SYMBOL(vm_insert_page);
> > >
> > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > +                     struct page **pages, unsigned long page_count)
> > > +{
> > > +     return -EINVAL;
> > > +}
> > > +EXPORT_SYMBOL(vm_insert_range);
> > > +
> > >  /*
> > >   *  sys_brk() for the most part doesn't need the global kernel
> > >   *  lock, except when an application is doing something nasty
> > > --
> > > 1.9.1
> > >
> >
> > --
> > Sincerely yours,
> > Mike.
> >
>
Souptick Joarder - Dec. 4, 2018, 6:46 a.m.
On Mon, Dec 3, 2018 at 11:52 AM Mike Rapoport <rppt@linux.ibm.com> wrote:
>
> On Mon, Dec 03, 2018 at 09:51:45AM +0530, Souptick Joarder wrote:
> > Hi Mike,
> >
> > On Sun, Dec 2, 2018 at 4:43 PM Mike Rapoport <rppt@linux.ibm.com> wrote:
> > >
> > > On Sun, Dec 02, 2018 at 11:49:44AM +0530, Souptick Joarder wrote:
> > > > Previouly drivers have their own way of mapping range of
> > > > kernel pages/memory into user vma and this was done by
> > > > invoking vm_insert_page() within a loop.
> > > >
> > > > As this pattern is common across different drivers, it can
> > > > be generalized by creating a new function and use it across
> > > > the drivers.
> > > >
> > > > vm_insert_range is the new API which will be used to map a
> > > > range of kernel memory/pages to user vma.
> > > >
> > > > This API is tested by Heiko for Rockchip drm driver, on rk3188,
> > > > rk3288, rk3328 and rk3399 with graphics.
> > > >
> > > > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > > > Reviewed-by: Matthew Wilcox <willy@infradead.org>
> > > > Tested-by: Heiko Stuebner <heiko@sntech.de>
> > > > ---
> > > >  include/linux/mm_types.h |  3 +++
> > > >  mm/memory.c              | 38 ++++++++++++++++++++++++++++++++++++++
> > > >  mm/nommu.c               |  7 +++++++
> > > >  3 files changed, 48 insertions(+)
> > > >
> > > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> > > > index 5ed8f62..15ae24f 100644
> > > > --- a/include/linux/mm_types.h
> > > > +++ b/include/linux/mm_types.h
> > > > @@ -523,6 +523,9 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
> > > >  extern void tlb_finish_mmu(struct mmu_gather *tlb,
> > > >                               unsigned long start, unsigned long end);
> > > >
> > > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > > +                     struct page **pages, unsigned long page_count);
> > > > +
> > >
> > > This seem to belong to include/linux/mm.h, near vm_insert_page()
> >
> > Ok, I will change it. Apart from this change does it looks good ?
>
> With this change you can add
>
> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

Thanks Mike.

>
> > >
> > > >  static inline void init_tlb_flush_pending(struct mm_struct *mm)
> > > >  {
> > > >       atomic_set(&mm->tlb_flush_pending, 0);
> > > > diff --git a/mm/memory.c b/mm/memory.c
> > > > index 15c417e..84ea46c 100644
> > > > --- a/mm/memory.c
> > > > +++ b/mm/memory.c
> > > > @@ -1478,6 +1478,44 @@ static int insert_page(struct vm_area_struct *vma, unsigned long addr,
> > > >  }
> > > >
> > > >  /**
> > > > + * vm_insert_range - insert range of kernel pages into user vma
> > > > + * @vma: user vma to map to
> > > > + * @addr: target user address of this page
> > > > + * @pages: pointer to array of source kernel pages
> > > > + * @page_count: number of pages need to insert into user vma
> > > > + *
> > > > + * This allows drivers to insert range of kernel pages they've allocated
> > > > + * into a user vma. This is a generic function which drivers can use
> > > > + * rather than using their own way of mapping range of kernel pages into
> > > > + * user vma.
> > > > + *
> > > > + * If we fail to insert any page into the vma, the function will return
> > > > + * immediately leaving any previously-inserted pages present.  Callers
> > > > + * from the mmap handler may immediately return the error as their caller
> > > > + * will destroy the vma, removing any successfully-inserted pages. Other
> > > > + * callers should make their own arrangements for calling unmap_region().
> > > > + *
> > > > + * Context: Process context. Called by mmap handlers.
> > > > + * Return: 0 on success and error code otherwise
> > > > + */
> > > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > > +                     struct page **pages, unsigned long page_count)
> > > > +{
> > > > +     unsigned long uaddr = addr;
> > > > +     int ret = 0, i;
> > > > +
> > > > +     for (i = 0; i < page_count; i++) {
> > > > +             ret = vm_insert_page(vma, uaddr, pages[i]);
> > > > +             if (ret < 0)
> > > > +                     return ret;
> > > > +             uaddr += PAGE_SIZE;
> > > > +     }
> > > > +
> > > > +     return ret;
> > > > +}
> > > > +EXPORT_SYMBOL(vm_insert_range);
> > > > +
> > > > +/**
> > > >   * vm_insert_page - insert single page into user vma
> > > >   * @vma: user vma to map to
> > > >   * @addr: target user address of this page
> > > > diff --git a/mm/nommu.c b/mm/nommu.c
> > > > index 749276b..d6ef5c7 100644
> > > > --- a/mm/nommu.c
> > > > +++ b/mm/nommu.c
> > > > @@ -473,6 +473,13 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
> > > >  }
> > > >  EXPORT_SYMBOL(vm_insert_page);
> > > >
> > > > +int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
> > > > +                     struct page **pages, unsigned long page_count)
> > > > +{
> > > > +     return -EINVAL;
> > > > +}
> > > > +EXPORT_SYMBOL(vm_insert_range);
> > > > +
> > > >  /*
> > > >   *  sys_brk() for the most part doesn't need the global kernel
> > > >   *  lock, except when an application is doing something nasty
> > > > --
> > > > 1.9.1
> > > >
> > >
> > > --
> > > Sincerely yours,
> > > Mike.
> > >
> >
>
> --
> Sincerely yours,
> Mike.
>

Patch

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 5ed8f62..15ae24f 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -523,6 +523,9 @@  extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
 extern void tlb_finish_mmu(struct mmu_gather *tlb,
 				unsigned long start, unsigned long end);
 
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+			struct page **pages, unsigned long page_count);
+
 static inline void init_tlb_flush_pending(struct mm_struct *mm)
 {
 	atomic_set(&mm->tlb_flush_pending, 0);
diff --git a/mm/memory.c b/mm/memory.c
index 15c417e..84ea46c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1478,6 +1478,44 @@  static int insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 
 /**
+ * vm_insert_range - insert range of kernel pages into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pages: pointer to array of source kernel pages
+ * @page_count: number of pages need to insert into user vma
+ *
+ * This allows drivers to insert range of kernel pages they've allocated
+ * into a user vma. This is a generic function which drivers can use
+ * rather than using their own way of mapping range of kernel pages into
+ * user vma.
+ *
+ * If we fail to insert any page into the vma, the function will return
+ * immediately leaving any previously-inserted pages present.  Callers
+ * from the mmap handler may immediately return the error as their caller
+ * will destroy the vma, removing any successfully-inserted pages. Other
+ * callers should make their own arrangements for calling unmap_region().
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise
+ */
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+			struct page **pages, unsigned long page_count)
+{
+	unsigned long uaddr = addr;
+	int ret = 0, i;
+
+	for (i = 0; i < page_count; i++) {
+		ret = vm_insert_page(vma, uaddr, pages[i]);
+		if (ret < 0)
+			return ret;
+		uaddr += PAGE_SIZE;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(vm_insert_range);
+
+/**
  * vm_insert_page - insert single page into user vma
  * @vma: user vma to map to
  * @addr: target user address of this page
diff --git a/mm/nommu.c b/mm/nommu.c
index 749276b..d6ef5c7 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -473,6 +473,13 @@  int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_page);
 
+int vm_insert_range(struct vm_area_struct *vma, unsigned long addr,
+			struct page **pages, unsigned long page_count)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vm_insert_range);
+
 /*
  *  sys_brk() for the most part doesn't need the global kernel
  *  lock, except when an application is doing something nasty

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