Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-10 Thread Greg Kroah-Hartman 
On Tue, Jun 10, 2014 at 04:04:53PM +0800, Yijing Wang wrote:
> >> +struct page *kmap_to_page(void *vaddr)
> >> +{
> >> +  unsigned long addr = (unsigned long)vaddr;
> >> +
> >> +  if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
> >> +  int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
> >> +  return pte_page(pkmap_page_table[i]);
> >> +  }
> >> +
> >> +  return virt_to_page(addr);
> >> +}
> >> +
> >>  static void flush_all_zero_pkmaps(void)
> >>  {
> >>int i;
> > 
> > I think this needs the following on top:
> > 
> > commit 498c2280212327858e521e9d21345d4cc2637f54
> > Author: Will Deacon 
> > Date:   Fri Nov 16 14:15:00 2012 -0800
> > 
> 
> Thanks Hugh. Hi Greg, please pick up this fix patch, Thanks a lot!

Now applied, thanks!

greg k-h
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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-10 Thread Yijing Wang 
>> +struct page *kmap_to_page(void *vaddr)
>> +{
>> +unsigned long addr = (unsigned long)vaddr;
>> +
>> +if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
>> +int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
>> +return pte_page(pkmap_page_table[i]);
>> +}
>> +
>> +return virt_to_page(addr);
>> +}
>> +
>>  static void flush_all_zero_pkmaps(void)
>>  {
>>  int i;
> 
> I think this needs the following on top:
> 
> commit 498c2280212327858e521e9d21345d4cc2637f54
> Author: Will Deacon 
> Date:   Fri Nov 16 14:15:00 2012 -0800
> 

Thanks Hugh. Hi Greg, please pick up this fix patch, Thanks a lot!

Yijing.


> mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
> 
> kmap_to_page returns the corresponding struct page for a virtual address
> of an arbitrary mapping.  This works by checking whether the address
> falls in the pkmap region and using the pkmap page tables instead of the
> linear mapping if appropriate.
> 
> Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is
> incorrectly treated as a highmem address and we can end up walking off
> the end of pkmap_page_table and subsequently passing junk to pte_page.
> 
> This patch fixes the bound check to stay within the pkmap tables.
> 
> Signed-off-by: Will Deacon 
> Cc: Mel Gorman 
> Signed-off-by: Andrew Morton 
> Signed-off-by: Linus Torvalds 
> 
> diff --git a/mm/highmem.c b/mm/highmem.c
> index d517cd16a6eb..2da13a5c50e2 100644
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr)
>  {
>   unsigned long addr = (unsigned long)vaddr;
>  
> - if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
> + if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
>   int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
>   return pte_page(pkmap_page_table[i]);
>   }
> 
> 
> .
> 


-- 
Thanks!
Yijing

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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-10 Thread Yijing Wang 
 +struct page *kmap_to_page(void *vaddr)
 +{
 +unsigned long addr = (unsigned long)vaddr;
 +
 +if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
 +int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
 +return pte_page(pkmap_page_table[i]);
 +}
 +
 +return virt_to_page(addr);
 +}
 +
  static void flush_all_zero_pkmaps(void)
  {
  int i;
 
 I think this needs the following on top:
 
 commit 498c2280212327858e521e9d21345d4cc2637f54
 Author: Will Deacon will.dea...@arm.com
 Date:   Fri Nov 16 14:15:00 2012 -0800
 

Thanks Hugh. Hi Greg, please pick up this fix patch, Thanks a lot!

Yijing.


 mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
 
 kmap_to_page returns the corresponding struct page for a virtual address
 of an arbitrary mapping.  This works by checking whether the address
 falls in the pkmap region and using the pkmap page tables instead of the
 linear mapping if appropriate.
 
 Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is
 incorrectly treated as a highmem address and we can end up walking off
 the end of pkmap_page_table and subsequently passing junk to pte_page.
 
 This patch fixes the bound check to stay within the pkmap tables.
 
 Signed-off-by: Will Deacon will.dea...@arm.com
 Cc: Mel Gorman mgor...@suse.de
 Signed-off-by: Andrew Morton a...@linux-foundation.org
 Signed-off-by: Linus Torvalds torva...@linux-foundation.org
 
 diff --git a/mm/highmem.c b/mm/highmem.c
 index d517cd16a6eb..2da13a5c50e2 100644
 --- a/mm/highmem.c
 +++ b/mm/highmem.c
 @@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr)
  {
   unsigned long addr = (unsigned long)vaddr;
  
 - if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
 + if (addr = PKMAP_ADDR(0)  addr  PKMAP_ADDR(LAST_PKMAP)) {
   int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
   return pte_page(pkmap_page_table[i]);
   }
 
 
 .
 


-- 
Thanks!
Yijing

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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-10 Thread Greg Kroah-Hartman 
On Tue, Jun 10, 2014 at 04:04:53PM +0800, Yijing Wang wrote:
  +struct page *kmap_to_page(void *vaddr)
  +{
  +  unsigned long addr = (unsigned long)vaddr;
  +
  +  if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
  +  int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
  +  return pte_page(pkmap_page_table[i]);
  +  }
  +
  +  return virt_to_page(addr);
  +}
  +
   static void flush_all_zero_pkmaps(void)
   {
 int i;
  
  I think this needs the following on top:
  
  commit 498c2280212327858e521e9d21345d4cc2637f54
  Author: Will Deacon will.dea...@arm.com
  Date:   Fri Nov 16 14:15:00 2012 -0800
  
 
 Thanks Hugh. Hi Greg, please pick up this fix patch, Thanks a lot!

Now applied, thanks!

greg k-h
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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Ben Hutchings 
On Mon, 2014-06-09 at 18:15 -0700, Hugh Dickins wrote:
> On Mon, 9 Jun 2014, Greg Kroah-Hartman wrote:
> 
> > 3.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > --
> > 
> > From: Ben Hutchings 
> > 
> > commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.
> > 
> > This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
> > support for direct_IO to highmem pages') upstream.
> > 
> > Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
> > physical address to userspace for high pages').
> > 
> > Cc: Mel Gorman 
> > Cc: Rik van Riel 
> > Cc: Andrew Morton 
> > Signed-off-by: Ben Hutchings 
> > Cc: Yijing Wang 
> > Signed-off-by: Greg Kroah-Hartman 
> > 
> > ---
> >  include/linux/highmem.h |7 +++
> >  mm/highmem.c|   12 
> >  2 files changed, 19 insertions(+)
> > 
> > --- a/include/linux/highmem.h
> > +++ b/include/linux/highmem.h
> > @@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
> >  
> >  void kmap_flush_unused(void);
> >  
> > +struct page *kmap_to_page(void *addr);
> > +
> >  #else /* CONFIG_HIGHMEM */
> >  
> >  static inline unsigned int nr_free_highpages(void) { return 0; }
> >  
> > +static inline struct page *kmap_to_page(void *addr)
> > +{
> > +   return virt_to_page(addr);
> > +}
> > +
> >  #define totalhigh_pages 0UL
> >  
> >  #ifndef ARCH_HAS_KMAP
> > --- a/mm/highmem.c
> > +++ b/mm/highmem.c
> > @@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
> > do { spin_unlock(_lock); (void)(flags); } while (0)
> >  #endif
> >  
> > +struct page *kmap_to_page(void *vaddr)
> > +{
> > +   unsigned long addr = (unsigned long)vaddr;
> > +
> > +   if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
> > +   int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
> > +   return pte_page(pkmap_page_table[i]);
> > +   }
> > +
> > +   return virt_to_page(addr);
> > +}
> > +
> >  static void flush_all_zero_pkmaps(void)
> >  {
> > int i;
> 
> I think this needs the following on top:
> 
> commit 498c2280212327858e521e9d21345d4cc2637f54
> Author: Will Deacon 
> Date:   Fri Nov 16 14:15:00 2012 -0800
> 
> mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
[...]

Thanks Hugh, I've queued this up for 3.2 (where I previously added
kmap_to_page()).

Ben.

-- 
Ben Hutchings


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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Hugh Dickins 
On Mon, 9 Jun 2014, Greg Kroah-Hartman wrote:

> 3.4-stable review patch.  If anyone has any objections, please let me know.
> 
> --
> 
> From: Ben Hutchings 
> 
> commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.
> 
> This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
> support for direct_IO to highmem pages') upstream.
> 
> Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
> physical address to userspace for high pages').
> 
> Cc: Mel Gorman 
> Cc: Rik van Riel 
> Cc: Andrew Morton 
> Signed-off-by: Ben Hutchings 
> Cc: Yijing Wang 
> Signed-off-by: Greg Kroah-Hartman 
> 
> ---
>  include/linux/highmem.h |7 +++
>  mm/highmem.c|   12 
>  2 files changed, 19 insertions(+)
> 
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
>  
>  void kmap_flush_unused(void);
>  
> +struct page *kmap_to_page(void *addr);
> +
>  #else /* CONFIG_HIGHMEM */
>  
>  static inline unsigned int nr_free_highpages(void) { return 0; }
>  
> +static inline struct page *kmap_to_page(void *addr)
> +{
> + return virt_to_page(addr);
> +}
> +
>  #define totalhigh_pages 0UL
>  
>  #ifndef ARCH_HAS_KMAP
> --- a/mm/highmem.c
> +++ b/mm/highmem.c
> @@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
>   do { spin_unlock(_lock); (void)(flags); } while (0)
>  #endif
>  
> +struct page *kmap_to_page(void *vaddr)
> +{
> + unsigned long addr = (unsigned long)vaddr;
> +
> + if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
> + int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
> + return pte_page(pkmap_page_table[i]);
> + }
> +
> + return virt_to_page(addr);
> +}
> +
>  static void flush_all_zero_pkmaps(void)
>  {
>   int i;

I think this needs the following on top:

commit 498c2280212327858e521e9d21345d4cc2637f54
Author: Will Deacon 
Date:   Fri Nov 16 14:15:00 2012 -0800

mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address

kmap_to_page returns the corresponding struct page for a virtual address
of an arbitrary mapping.  This works by checking whether the address
falls in the pkmap region and using the pkmap page tables instead of the
linear mapping if appropriate.

Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is
incorrectly treated as a highmem address and we can end up walking off
the end of pkmap_page_table and subsequently passing junk to pte_page.

This patch fixes the bound check to stay within the pkmap tables.

Signed-off-by: Will Deacon 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 

diff --git a/mm/highmem.c b/mm/highmem.c
index d517cd16a6eb..2da13a5c50e2 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr)
 {
unsigned long addr = (unsigned long)vaddr;
 
-   if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
+   if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {
int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
return pte_page(pkmap_page_table[i]);
}

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[PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Greg Kroah-Hartman 
3.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Ben Hutchings 

commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.

This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
support for direct_IO to highmem pages') upstream.

Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
physical address to userspace for high pages').

Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Andrew Morton 
Signed-off-by: Ben Hutchings 
Cc: Yijing Wang 
Signed-off-by: Greg Kroah-Hartman 

---
 include/linux/highmem.h |7 +++
 mm/highmem.c|   12 
 2 files changed, 19 insertions(+)

--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
 
 void kmap_flush_unused(void);
 
+struct page *kmap_to_page(void *addr);
+
 #else /* CONFIG_HIGHMEM */
 
 static inline unsigned int nr_free_highpages(void) { return 0; }
 
+static inline struct page *kmap_to_page(void *addr)
+{
+   return virt_to_page(addr);
+}
+
 #define totalhigh_pages 0UL
 
 #ifndef ARCH_HAS_KMAP
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
do { spin_unlock(_lock); (void)(flags); } while (0)
 #endif
 
+struct page *kmap_to_page(void *vaddr)
+{
+   unsigned long addr = (unsigned long)vaddr;
+
+   if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) {
+   int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT;
+   return pte_page(pkmap_page_table[i]);
+   }
+
+   return virt_to_page(addr);
+}
+
 static void flush_all_zero_pkmaps(void)
 {
int i;


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[PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Greg Kroah-Hartman 
3.4-stable review patch.  If anyone has any objections, please let me know.

--

From: Ben Hutchings b...@decadent.org.uk

commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.

This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
support for direct_IO to highmem pages') upstream.

Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
physical address to userspace for high pages').

Cc: Mel Gorman mgor...@suse.de
Cc: Rik van Riel r...@redhat.com
Cc: Andrew Morton a...@linux-foundation.org
Signed-off-by: Ben Hutchings b...@decadent.org.uk
Cc: Yijing Wang wangyij...@huawei.com
Signed-off-by: Greg Kroah-Hartman gre...@linuxfoundation.org

---
 include/linux/highmem.h |7 +++
 mm/highmem.c|   12 
 2 files changed, 19 insertions(+)

--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
 
 void kmap_flush_unused(void);
 
+struct page *kmap_to_page(void *addr);
+
 #else /* CONFIG_HIGHMEM */
 
 static inline unsigned int nr_free_highpages(void) { return 0; }
 
+static inline struct page *kmap_to_page(void *addr)
+{
+   return virt_to_page(addr);
+}
+
 #define totalhigh_pages 0UL
 
 #ifndef ARCH_HAS_KMAP
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
do { spin_unlock(kmap_lock); (void)(flags); } while (0)
 #endif
 
+struct page *kmap_to_page(void *vaddr)
+{
+   unsigned long addr = (unsigned long)vaddr;
+
+   if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
+   int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
+   return pte_page(pkmap_page_table[i]);
+   }
+
+   return virt_to_page(addr);
+}
+
 static void flush_all_zero_pkmaps(void)
 {
int i;


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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Hugh Dickins 
On Mon, 9 Jun 2014, Greg Kroah-Hartman wrote:

 3.4-stable review patch.  If anyone has any objections, please let me know.
 
 --
 
 From: Ben Hutchings b...@decadent.org.uk
 
 commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.
 
 This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
 support for direct_IO to highmem pages') upstream.
 
 Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
 physical address to userspace for high pages').
 
 Cc: Mel Gorman mgor...@suse.de
 Cc: Rik van Riel r...@redhat.com
 Cc: Andrew Morton a...@linux-foundation.org
 Signed-off-by: Ben Hutchings b...@decadent.org.uk
 Cc: Yijing Wang wangyij...@huawei.com
 Signed-off-by: Greg Kroah-Hartman gre...@linuxfoundation.org
 
 ---
  include/linux/highmem.h |7 +++
  mm/highmem.c|   12 
  2 files changed, 19 insertions(+)
 
 --- a/include/linux/highmem.h
 +++ b/include/linux/highmem.h
 @@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
  
  void kmap_flush_unused(void);
  
 +struct page *kmap_to_page(void *addr);
 +
  #else /* CONFIG_HIGHMEM */
  
  static inline unsigned int nr_free_highpages(void) { return 0; }
  
 +static inline struct page *kmap_to_page(void *addr)
 +{
 + return virt_to_page(addr);
 +}
 +
  #define totalhigh_pages 0UL
  
  #ifndef ARCH_HAS_KMAP
 --- a/mm/highmem.c
 +++ b/mm/highmem.c
 @@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
   do { spin_unlock(kmap_lock); (void)(flags); } while (0)
  #endif
  
 +struct page *kmap_to_page(void *vaddr)
 +{
 + unsigned long addr = (unsigned long)vaddr;
 +
 + if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
 + int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
 + return pte_page(pkmap_page_table[i]);
 + }
 +
 + return virt_to_page(addr);
 +}
 +
  static void flush_all_zero_pkmaps(void)
  {
   int i;

I think this needs the following on top:

commit 498c2280212327858e521e9d21345d4cc2637f54
Author: Will Deacon will.dea...@arm.com
Date:   Fri Nov 16 14:15:00 2012 -0800

mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address

kmap_to_page returns the corresponding struct page for a virtual address
of an arbitrary mapping.  This works by checking whether the address
falls in the pkmap region and using the pkmap page tables instead of the
linear mapping if appropriate.

Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is
incorrectly treated as a highmem address and we can end up walking off
the end of pkmap_page_table and subsequently passing junk to pte_page.

This patch fixes the bound check to stay within the pkmap tables.

Signed-off-by: Will Deacon will.dea...@arm.com
Cc: Mel Gorman mgor...@suse.de
Signed-off-by: Andrew Morton a...@linux-foundation.org
Signed-off-by: Linus Torvalds torva...@linux-foundation.org

diff --git a/mm/highmem.c b/mm/highmem.c
index d517cd16a6eb..2da13a5c50e2 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr)
 {
unsigned long addr = (unsigned long)vaddr;
 
-   if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
+   if (addr = PKMAP_ADDR(0)  addr  PKMAP_ADDR(LAST_PKMAP)) {
int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
return pte_page(pkmap_page_table[i]);
}

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Re: [PATCH 3.4 47/88] mm: add kmap_to_page()

2014-06-09 Thread Ben Hutchings 
On Mon, 2014-06-09 at 18:15 -0700, Hugh Dickins wrote:
 On Mon, 9 Jun 2014, Greg Kroah-Hartman wrote:
 
  3.4-stable review patch.  If anyone has any objections, please let me know.
  
  --
  
  From: Ben Hutchings b...@decadent.org.uk
  
  commit fcb8996728fb59eddf84678df7cb213b2c9a2e26 upstream.
  
  This is extracted from Mel Gorman's commit 5a178119b0fb ('mm: add
  support for direct_IO to highmem pages') upstream.
  
  Required to backport commit b9cdc88df8e6 ('virtio: 9p: correctly pass
  physical address to userspace for high pages').
  
  Cc: Mel Gorman mgor...@suse.de
  Cc: Rik van Riel r...@redhat.com
  Cc: Andrew Morton a...@linux-foundation.org
  Signed-off-by: Ben Hutchings b...@decadent.org.uk
  Cc: Yijing Wang wangyij...@huawei.com
  Signed-off-by: Greg Kroah-Hartman gre...@linuxfoundation.org
  
  ---
   include/linux/highmem.h |7 +++
   mm/highmem.c|   12 
   2 files changed, 19 insertions(+)
  
  --- a/include/linux/highmem.h
  +++ b/include/linux/highmem.h
  @@ -39,10 +39,17 @@ extern unsigned long totalhigh_pages;
   
   void kmap_flush_unused(void);
   
  +struct page *kmap_to_page(void *addr);
  +
   #else /* CONFIG_HIGHMEM */
   
   static inline unsigned int nr_free_highpages(void) { return 0; }
   
  +static inline struct page *kmap_to_page(void *addr)
  +{
  +   return virt_to_page(addr);
  +}
  +
   #define totalhigh_pages 0UL
   
   #ifndef ARCH_HAS_KMAP
  --- a/mm/highmem.c
  +++ b/mm/highmem.c
  @@ -94,6 +94,18 @@ static DECLARE_WAIT_QUEUE_HEAD(pkmap_map
  do { spin_unlock(kmap_lock); (void)(flags); } while (0)
   #endif
   
  +struct page *kmap_to_page(void *vaddr)
  +{
  +   unsigned long addr = (unsigned long)vaddr;
  +
  +   if (addr = PKMAP_ADDR(0)  addr = PKMAP_ADDR(LAST_PKMAP)) {
  +   int i = (addr - PKMAP_ADDR(0))  PAGE_SHIFT;
  +   return pte_page(pkmap_page_table[i]);
  +   }
  +
  +   return virt_to_page(addr);
  +}
  +
   static void flush_all_zero_pkmaps(void)
   {
  int i;
 
 I think this needs the following on top:
 
 commit 498c2280212327858e521e9d21345d4cc2637f54
 Author: Will Deacon will.dea...@arm.com
 Date:   Fri Nov 16 14:15:00 2012 -0800
 
 mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address
[...]

Thanks Hugh, I've queued this up for 3.2 (where I previously added
kmap_to_page()).

Ben.

-- 
Ben Hutchings


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