[PATCH] mm/hugetlb: Fix build failure with HUGETLB_PAGE but not HUGEBTLBFS

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

In file included from arch/powerpc/mm/fault.c:33:0:
./include/linux/hugetlb.h: In function 'hstate_inode':
./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
  return HUGETLBFS_SB(i->i_sb)->hstate;
         ^
./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
  return HUGETLBFS_SB(i->i_sb)->hstate;
                              ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Reported-by: kbuild test robot <redacted>
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <redacted>
---
 include/linux/hugetlb.h | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 1e897e4168ac..dafb3d70ff81 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h

@@ -390,7 +390,10 @@ static inline bool is_file_hugepages(struct file *file)
 	return is_file_shm_hugepages(file);
 }
 
-
+static inline struct hstate *hstate_inode(struct inode *i)
+{
+	return HUGETLBFS_SB(i->i_sb)->hstate;
+}
 #else /* !CONFIG_HUGETLBFS */
 
 #define is_file_hugepages(file)			false

@@ -402,6 +405,10 @@ hugetlb_file_setup(const char *name, size_t size, vm_flags_t acctflag,
 	return ERR_PTR(-ENOSYS);
 }
 
+static inline struct hstate *hstate_inode(struct inode *i)
+{
+	return NULL;
+}
 #endif /* !CONFIG_HUGETLBFS */
 
 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA

@@ -472,11 +479,6 @@ extern unsigned int default_hstate_idx;
 
 #define default_hstate (hstates[default_hstate_idx])
 
-static inline struct hstate *hstate_inode(struct inode *i)
-{
-	return HUGETLBFS_SB(i->i_sb)->hstate;
-}
-
 static inline struct hstate *hstate_file(struct file *f)
 {
 	return hstate_inode(file_inode(f));

@@ -729,11 +731,6 @@ static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
 	return NULL;
 }
 
-static inline struct hstate *hstate_inode(struct inode *i)
-{
-	return NULL;
-}
-
 static inline struct hstate *page_hstate(struct page *page)
 {
 	return NULL;

-- 
2.25.0

On 03/17/20 at 08:04am, Christophe Leroy wrote:

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
I could misunderstand the def_bool, please correct me if I am wrong.

config HUGETLB_PAGE
        def_bool HUGETLBFS

Le 17/03/2020 à 09:25, Baoquan He a écrit :

On 03/17/20 at 08:04am, Christophe Leroy wrote:

quoted

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

 From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
I could misunderstand the def_bool, please correct me if I am wrong.

AFAIU, it means that HUGETLBFS rely on HUGETLB_PAGE, by default 
HUGETLB_PAGE is not selected when HUGETLBFS is not. But it is still 
possible for an arch to select HUGETLB_PAGE without selecting HUGETLBFS 
when it uses huge pages for other purpose than hugetlb file system.

Christophe

config HUGETLB_PAGE
         def_bool HUGETLBFS

quoted

In file included from arch/powerpc/mm/fault.c:33:0:
./include/linux/hugetlb.h: In function 'hstate_inode':
./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
   return HUGETLBFS_SB(i->i_sb)->hstate;
          ^
./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
   return HUGETLBFS_SB(i->i_sb)->hstate;
                               ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Reported-by: kbuild test robot <redacted>
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <redacted>
---
  include/linux/hugetlb.h | 19 ++++++++-----------
  1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 1e897e4168ac..dafb3d70ff81 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h

@@ -390,7 +390,10 @@ static inline bool is_file_hugepages(struct file *file)
  	return is_file_shm_hugepages(file);
  }
  
-
+static inline struct hstate *hstate_inode(struct inode *i)
+{
+	return HUGETLBFS_SB(i->i_sb)->hstate;
+}
  #else /* !CONFIG_HUGETLBFS */
  
  #define is_file_hugepages(file)			false

@@ -402,6 +405,10 @@ hugetlb_file_setup(const char *name, size_t size, vm_flags_t acctflag,
  	return ERR_PTR(-ENOSYS);
  }
  
+static inline struct hstate *hstate_inode(struct inode *i)
+{
+	return NULL;
+}
  #endif /* !CONFIG_HUGETLBFS */
  
  #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA

@@ -472,11 +479,6 @@ extern unsigned int default_hstate_idx;
  
  #define default_hstate (hstates[default_hstate_idx])
  
-static inline struct hstate *hstate_inode(struct inode *i)
-{
-	return HUGETLBFS_SB(i->i_sb)->hstate;
-}
-
  static inline struct hstate *hstate_file(struct file *f)
  {
  	return hstate_inode(file_inode(f));

@@ -729,11 +731,6 @@ static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
  	return NULL;
  }
  
-static inline struct hstate *hstate_inode(struct inode *i)
-{
-	return NULL;
-}
-
  static inline struct hstate *page_hstate(struct page *page)
  {
  	return NULL;

-- 
2.25.0

On 3/17/20 1:43 AM, Christophe Leroy wrote:

Le 17/03/2020 à 09:25, Baoquan He a écrit :

quoted

On 03/17/20 at 08:04am, Christophe Leroy wrote:

quoted

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

 From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
I could misunderstand the def_bool, please correct me if I am wrong.

AFAIU, it means that HUGETLBFS rely on HUGETLB_PAGE, by default HUGETLB_PAGE is not selected when HUGETLBFS is not. But it is still possible for an arch to select HUGETLB_PAGE without selecting HUGETLBFS when it uses huge pages for other purpose than hugetlb file system.

Hi Christophe,

Do you actually have a use case/example of using hugetlb pages without
hugetlbfs?  I can understand that there are some use cases which never
use the filesystem interface.  However, hugetlb support is so intertwined
with hugetlbfs, I am thinking there would be issues trying to use them
separately.  I will look into this further.

-- 
Mike Kravetz

Le 17/03/2020 à 17:40, Mike Kravetz a écrit :

On 3/17/20 1:43 AM, Christophe Leroy wrote:

quoted

Le 17/03/2020 à 09:25, Baoquan He a écrit :

quoted

On 03/17/20 at 08:04am, Christophe Leroy wrote:

quoted

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

  From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
I could misunderstand the def_bool, please correct me if I am wrong.

AFAIU, it means that HUGETLBFS rely on HUGETLB_PAGE, by default HUGETLB_PAGE is not selected when HUGETLBFS is not. But it is still possible for an arch to select HUGETLB_PAGE without selecting HUGETLBFS when it uses huge pages for other purpose than hugetlb file system.

Hi Christophe,

Do you actually have a use case/example of using hugetlb pages without
hugetlbfs?  I can understand that there are some use cases which never
use the filesystem interface.  However, hugetlb support is so intertwined
with hugetlbfs, I am thinking there would be issues trying to use them
separately.  I will look into this further.

Hi Mike,

Series https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=164620

And especially patch 39 to 41.

Thanks
Christophe

On 3/17/20 9:47 AM, Christophe Leroy wrote:

Le 17/03/2020 à 17:40, Mike Kravetz a écrit :

quoted

On 3/17/20 1:43 AM, Christophe Leroy wrote:

quoted

Le 17/03/2020 à 09:25, Baoquan He a écrit :

quoted

On 03/17/20 at 08:04am, Christophe Leroy wrote:

quoted

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

  From the definition of HUGETLB_PAGE, isn't it relying on HUGETLBFS?
I could misunderstand the def_bool, please correct me if I am wrong.

AFAIU, it means that HUGETLBFS rely on HUGETLB_PAGE, by default HUGETLB_PAGE is not selected when HUGETLBFS is not. But it is still possible for an arch to select HUGETLB_PAGE without selecting HUGETLBFS when it uses huge pages for other purpose than hugetlb file system.

Hi Christophe,

Do you actually have a use case/example of using hugetlb pages without
hugetlbfs?  I can understand that there are some use cases which never
use the filesystem interface.  However, hugetlb support is so intertwined
with hugetlbfs, I am thinking there would be issues trying to use them
separately.  I will look into this further.

Hi Mike,

Series https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=164620

And especially patch 39 to 41.

Ah, ok.  You are simply using a few interfaces in the hugetlb header files.
The huge pages created in your mappings are not PageHuge() pages.

-- 
Mike Kravetz

On 3/17/20 1:04 AM, Christophe Leroy wrote:

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

In file included from arch/powerpc/mm/fault.c:33:0:
./include/linux/hugetlb.h: In function 'hstate_inode':
./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
  return HUGETLBFS_SB(i->i_sb)->hstate;
         ^
./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
  return HUGETLBFS_SB(i->i_sb)->hstate;
                              ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Reported-by: kbuild test robot <redacted>
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <redacted>

As hugetlb.h evolved over time, I suspect nobody imagined a configuration
with CONFIG_HUGETLB_PAGE and not CONFIG_HUGETLBFS.  This patch does address
the build issues.  So,

Reviewed-by: Mike Kravetz <redacted>

However, there are many definitions in that file not behind #ifdef
CONFIG_HUGETLBFS that make no sense unless CONFIG_HUGETLBFS is defined.
Such cleanup is way beyond the scope of this patch/effort.  I will add
it to the list of hugetlb/hugetlbfs things that can be cleaned up.
-- 
Mike Kravetz

On Tue, 17 Mar 2020 08:04:14 +0000 (UTC) Christophe Leroy [off-list ref] wrote:

When CONFIG_HUGETLB_PAGE is set but not CONFIG_HUGETLBFS, the
following build failure is encoutered:

In file included from arch/powerpc/mm/fault.c:33:0:
./include/linux/hugetlb.h: In function 'hstate_inode':
./include/linux/hugetlb.h:477:9: error: implicit declaration of function 'HUGETLBFS_SB' [-Werror=implicit-function-declaration]
  return HUGETLBFS_SB(i->i_sb)->hstate;
         ^
./include/linux/hugetlb.h:477:30: error: invalid type argument of '->' (have 'int')
  return HUGETLBFS_SB(i->i_sb)->hstate;
                              ^

Gate hstate_inode() with CONFIG_HUGETLBFS instead of CONFIG_HUGETLB_PAGE.

Reported-by: kbuild test robot <redacted>
Link: https://patchwork.ozlabs.org/patch/1255548/#2386036
Fixes: a137e1cc6d6e ("hugetlbfs: per mount huge page sizes")

A 12 year old build error?  If accurate, that has to be a world record.

Cc: stable@vger.kernel.org

I think I'll remove this.  Obviously nobody is suffering from this problem!