diff mbox series

[13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step

Message ID 20230105101844.1893104-14-jthoughton@google.com (mailing list archive)
State New
Headers show
Series Based on latest mm-unstable (85b44c25cd1e). | expand

Commit Message

James Houghton Jan. 5, 2023, 10:18 a.m. UTC
hugetlb_hgm_walk implements high-granularity page table walks for
HugeTLB. It is safe to call on non-HGM enabled VMAs; it will return
immediately.

hugetlb_walk_step implements how we step forwards in the walk. For
architectures that don't use GENERAL_HUGETLB, they will need to provide
their own implementation.

Signed-off-by: James Houghton <jthoughton@google.com>
---
 include/linux/hugetlb.h |  35 +++++--
 mm/hugetlb.c            | 213 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 242 insertions(+), 6 deletions(-)

Comments

kernel test robot Jan. 5, 2023, 4:57 p.m. UTC | #1
Hi James,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20230105]
[cannot apply to kvm/queue shuah-kselftest/next shuah-kselftest/fixes arnd-asm-generic/master linus/master kvm/linux-next v6.2-rc2 v6.2-rc1 v6.1 v6.2-rc2]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230105-182428
patch link:    https://lore.kernel.org/r/20230105101844.1893104-14-jthoughton%40google.com
patch subject: [PATCH 13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step
config: m68k-allmodconfig
compiler: m68k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/5395f068d45f39d202240799d3a8146226387f5c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230105-182428
        git checkout 5395f068d45f39d202240799d3a8146226387f5c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash fs/proc/ mm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from include/linux/migrate.h:8,
                    from mm/zsmalloc.c:60:
>> include/linux/hugetlb.h:1275:34: error: return type is an incomplete type
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hpage_size_to_level':
>> include/linux/hugetlb.h:1277:16: error: 'HUGETLB_LEVEL_PTE' undeclared (first use in this function)
    1277 |         return HUGETLB_LEVEL_PTE;
         |                ^~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h:1277:16: note: each undeclared identifier is reported only once for each function it appears in
   include/linux/hugetlb.h:1277:16: error: 'return' with a value, in function returning void [-Werror=return-type]
   include/linux/hugetlb.h:1275:34: note: declared here
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1306:40: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                        ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lockptr':
   include/linux/hugetlb.h:1308:20: error: invalid use of undefined type 'struct hugetlb_pte'
    1308 |         return hpte->ptl;
         |                    ^~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1312:37: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1312 | spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
         |                                     ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lock':
   include/linux/hugetlb.h:1314:47: error: passing argument 1 of 'hugetlb_pte_lockptr' from incompatible pointer type [-Werror=incompatible-pointer-types]
    1314 |         spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
         |                                               ^~~~
         |                                               |
         |                                               struct hugetlb_pte *
   include/linux/hugetlb.h:1306:53: note: expected 'struct hugetlb_pte *' but argument is of type 'struct hugetlb_pte *'
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                 ~~~~~~~~~~~~~~~~~~~~^~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1321:56: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |                                                        ^~~~~~~~~~~
   include/linux/hugetlb.h:1323:46: error: parameter 5 ('level') has incomplete type
    1323 |                           enum hugetlb_level level)
         |                           ~~~~~~~~~~~~~~~~~~~^~~~~
   include/linux/hugetlb.h:1321:6: error: function declaration isn't a prototype [-Werror=strict-prototypes]
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |      ^~~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_populate':
   include/linux/hugetlb.h:1325:9: error: implicit declaration of function '__hugetlb_pte_populate'; did you mean 'hugetlb_pte_populate'? [-Werror=implicit-function-declaration]
    1325 |         __hugetlb_pte_populate(hpte, ptep, shift, level,
         |         ^~~~~~~~~~~~~~~~~~~~~~
         |         hugetlb_pte_populate
   cc1: some warnings being treated as errors
--
   In file included from mm/madvise.c:16:
>> include/linux/hugetlb.h:1275:34: error: return type is an incomplete type
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hpage_size_to_level':
>> include/linux/hugetlb.h:1277:16: error: 'HUGETLB_LEVEL_PTE' undeclared (first use in this function)
    1277 |         return HUGETLB_LEVEL_PTE;
         |                ^~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h:1277:16: note: each undeclared identifier is reported only once for each function it appears in
   include/linux/hugetlb.h:1277:16: error: 'return' with a value, in function returning void [-Werror=return-type]
   include/linux/hugetlb.h:1275:34: note: declared here
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1306:40: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                        ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lockptr':
   include/linux/hugetlb.h:1308:20: error: invalid use of undefined type 'struct hugetlb_pte'
    1308 |         return hpte->ptl;
         |                    ^~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1312:37: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1312 | spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
         |                                     ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lock':
   include/linux/hugetlb.h:1314:47: error: passing argument 1 of 'hugetlb_pte_lockptr' from incompatible pointer type [-Werror=incompatible-pointer-types]
    1314 |         spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
         |                                               ^~~~
         |                                               |
         |                                               struct hugetlb_pte *
   include/linux/hugetlb.h:1306:53: note: expected 'struct hugetlb_pte *' but argument is of type 'struct hugetlb_pte *'
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                 ~~~~~~~~~~~~~~~~~~~~^~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1321:56: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |                                                        ^~~~~~~~~~~
   include/linux/hugetlb.h:1323:46: error: parameter 5 ('level') has incomplete type
    1323 |                           enum hugetlb_level level)
         |                           ~~~~~~~~~~~~~~~~~~~^~~~~
   include/linux/hugetlb.h:1321:6: error: function declaration isn't a prototype [-Werror=strict-prototypes]
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |      ^~~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_populate':
   include/linux/hugetlb.h:1325:9: error: implicit declaration of function '__hugetlb_pte_populate'; did you mean 'hugetlb_pte_populate'? [-Werror=implicit-function-declaration]
    1325 |         __hugetlb_pte_populate(hpte, ptep, shift, level,
         |         ^~~~~~~~~~~~~~~~~~~~~~
         |         hugetlb_pte_populate
   mm/madvise.c: In function 'madvise_split':
   mm/madvise.c:1023:9: error: implicit declaration of function 'hugetlb_vma_lock_alloc'; did you mean 'hugetlb_vma_lock_write'? [-Werror=implicit-function-declaration]
    1023 |         hugetlb_vma_lock_alloc(vma);
         |         ^~~~~~~~~~~~~~~~~~~~~~
         |         hugetlb_vma_lock_write
   cc1: some warnings being treated as errors
--
   In file included from fs/proc/meminfo.c:6:
>> include/linux/hugetlb.h:1275:34: error: return type is an incomplete type
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hpage_size_to_level':
>> include/linux/hugetlb.h:1277:16: error: 'HUGETLB_LEVEL_PTE' undeclared (first use in this function)
    1277 |         return HUGETLB_LEVEL_PTE;
         |                ^~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h:1277:16: note: each undeclared identifier is reported only once for each function it appears in
   include/linux/hugetlb.h:1277:16: error: 'return' with a value, in function returning void [-Werror=return-type]
   include/linux/hugetlb.h:1275:34: note: declared here
    1275 | static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
         |                                  ^~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1306:40: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                        ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lockptr':
   include/linux/hugetlb.h:1308:20: error: invalid use of undefined type 'struct hugetlb_pte'
    1308 |         return hpte->ptl;
         |                    ^~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1312:37: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1312 | spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
         |                                     ^~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_lock':
   include/linux/hugetlb.h:1314:47: error: passing argument 1 of 'hugetlb_pte_lockptr' from incompatible pointer type [-Werror=incompatible-pointer-types]
    1314 |         spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
         |                                               ^~~~
         |                                               |
         |                                               struct hugetlb_pte *
   include/linux/hugetlb.h:1306:53: note: expected 'struct hugetlb_pte *' but argument is of type 'struct hugetlb_pte *'
    1306 | spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
         |                                 ~~~~~~~~~~~~~~~~~~~~^~~~
   include/linux/hugetlb.h: At top level:
   include/linux/hugetlb.h:1321:56: warning: 'struct hugetlb_pte' declared inside parameter list will not be visible outside of this definition or declaration
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |                                                        ^~~~~~~~~~~
   include/linux/hugetlb.h:1323:46: error: parameter 5 ('level') has incomplete type
    1323 |                           enum hugetlb_level level)
         |                           ~~~~~~~~~~~~~~~~~~~^~~~~
   include/linux/hugetlb.h:1321:6: error: function declaration isn't a prototype [-Werror=strict-prototypes]
    1321 | void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
         |      ^~~~~~~~~~~~~~~~~~~~
   include/linux/hugetlb.h: In function 'hugetlb_pte_populate':
   include/linux/hugetlb.h:1325:9: error: implicit declaration of function '__hugetlb_pte_populate'; did you mean 'hugetlb_pte_populate'? [-Werror=implicit-function-declaration]
    1325 |         __hugetlb_pte_populate(hpte, ptep, shift, level,
         |         ^~~~~~~~~~~~~~~~~~~~~~
         |         hugetlb_pte_populate
   fs/proc/meminfo.c: At top level:
   fs/proc/meminfo.c:22:28: warning: no previous prototype for 'arch_report_meminfo' [-Wmissing-prototypes]
      22 | void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
         |                            ^~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +1275 include/linux/hugetlb.h

  1274	
> 1275	static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
  1276	{
> 1277		return HUGETLB_LEVEL_PTE;
  1278	}
  1279	#endif	/* CONFIG_HUGETLB_PAGE */
  1280
kernel test robot Jan. 5, 2023, 6:58 p.m. UTC | #2
Hi James,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20230105]
[cannot apply to kvm/queue shuah-kselftest/next shuah-kselftest/fixes arnd-asm-generic/master linus/master kvm/linux-next v6.2-rc2 v6.2-rc1 v6.1 v6.2-rc2]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230105-182428
patch link:    https://lore.kernel.org/r/20230105101844.1893104-14-jthoughton%40google.com
patch subject: [PATCH 13/46] hugetlb: add hugetlb_hgm_walk and hugetlb_walk_step
config: powerpc-randconfig-r005-20230105
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 8d9828ef5aa9688500657d36cd2aefbe12bbd162)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # https://github.com/intel-lab-lkp/linux/commit/5395f068d45f39d202240799d3a8146226387f5c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review James-Houghton/hugetlb-don-t-set-PageUptodate-for-UFFDIO_CONTINUE/20230105-182428
        git checkout 5395f068d45f39d202240799d3a8146226387f5c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash fs/proc/ mm/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from mm/filemap.c:36:
>> include/linux/hugetlb.h:1275:34: error: incomplete result type 'enum hugetlb_level' in function definition
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                                    ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
>> include/linux/hugetlb.h:1277:9: error: use of undeclared identifier 'HUGETLB_LEVEL_PTE'
           return HUGETLB_LEVEL_PTE;
                  ^
   include/linux/hugetlb.h:1306:40: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1308:13: error: incomplete definition of type 'struct hugetlb_pte'
           return hpte->ptl;
                  ~~~~^
   include/linux/hugetlb.h:1306:40: note: forward declaration of 'struct hugetlb_pte'
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1312:37: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
                                       ^
   include/linux/hugetlb.h:1314:40: error: incompatible pointer types passing 'struct hugetlb_pte *' to parameter of type 'struct hugetlb_pte *' [-Werror,-Wincompatible-pointer-types]
           spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
                                                 ^~~~
   include/linux/hugetlb.h:1306:53: note: passing argument to parameter 'hpte' here
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                                       ^
   include/linux/hugetlb.h:1321:56: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
                                                          ^
   include/linux/hugetlb.h:1323:25: error: variable has incomplete type 'enum hugetlb_level'
                             enum hugetlb_level level)
                                                ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
   include/linux/hugetlb.h:1325:2: error: call to undeclared function '__hugetlb_pte_populate'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           __hugetlb_pte_populate(hpte, ptep, shift, level,
           ^
   include/linux/hugetlb.h:1325:2: note: did you mean 'hugetlb_pte_populate'?
   include/linux/hugetlb.h:1321:6: note: 'hugetlb_pte_populate' declared here
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
        ^
   3 warnings and 6 errors generated.
--
   In file included from mm/shmem.c:38:
>> include/linux/hugetlb.h:1275:34: error: incomplete result type 'enum hugetlb_level' in function definition
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                                    ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
>> include/linux/hugetlb.h:1277:9: error: use of undeclared identifier 'HUGETLB_LEVEL_PTE'
           return HUGETLB_LEVEL_PTE;
                  ^
   include/linux/hugetlb.h:1306:40: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1308:13: error: incomplete definition of type 'struct hugetlb_pte'
           return hpte->ptl;
                  ~~~~^
   include/linux/hugetlb.h:1306:40: note: forward declaration of 'struct hugetlb_pte'
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1312:37: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
                                       ^
   include/linux/hugetlb.h:1314:40: error: incompatible pointer types passing 'struct hugetlb_pte *' to parameter of type 'struct hugetlb_pte *' [-Werror,-Wincompatible-pointer-types]
           spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
                                                 ^~~~
   include/linux/hugetlb.h:1306:53: note: passing argument to parameter 'hpte' here
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                                       ^
   include/linux/hugetlb.h:1321:56: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
                                                          ^
   include/linux/hugetlb.h:1323:25: error: variable has incomplete type 'enum hugetlb_level'
                             enum hugetlb_level level)
                                                ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
   include/linux/hugetlb.h:1325:2: error: call to undeclared function '__hugetlb_pte_populate'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           __hugetlb_pte_populate(hpte, ptep, shift, level,
           ^
   include/linux/hugetlb.h:1325:2: note: did you mean 'hugetlb_pte_populate'?
   include/linux/hugetlb.h:1321:6: note: 'hugetlb_pte_populate' declared here
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
        ^
   In file included from mm/shmem.c:57:
   include/linux/mman.h:153:9: warning: division by zero is undefined [-Wdivision-by-zero]
                  _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/mman.h:132:21: note: expanded from macro '_calc_vm_trans'
      : ((x) & (bit1)) / ((bit1) / (bit2))))
                       ^ ~~~~~~~~~~~~~~~~~
   include/linux/mman.h:154:9: warning: division by zero is undefined [-Wdivision-by-zero]
                  _calc_vm_trans(flags, MAP_SYNC,       VM_SYNC      ) |
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/mman.h:132:21: note: expanded from macro '_calc_vm_trans'
      : ((x) & (bit1)) / ((bit1) / (bit2))))
                       ^ ~~~~~~~~~~~~~~~~~
   5 warnings and 6 errors generated.
--
   In file included from fs/proc/meminfo.c:6:
>> include/linux/hugetlb.h:1275:34: error: incomplete result type 'enum hugetlb_level' in function definition
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                                    ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
>> include/linux/hugetlb.h:1277:9: error: use of undeclared identifier 'HUGETLB_LEVEL_PTE'
           return HUGETLB_LEVEL_PTE;
                  ^
   include/linux/hugetlb.h:1306:40: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1308:13: error: incomplete definition of type 'struct hugetlb_pte'
           return hpte->ptl;
                  ~~~~^
   include/linux/hugetlb.h:1306:40: note: forward declaration of 'struct hugetlb_pte'
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                          ^
   include/linux/hugetlb.h:1312:37: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   spinlock_t *hugetlb_pte_lock(struct hugetlb_pte *hpte)
                                       ^
   include/linux/hugetlb.h:1314:40: error: incompatible pointer types passing 'struct hugetlb_pte *' to parameter of type 'struct hugetlb_pte *' [-Werror,-Wincompatible-pointer-types]
           spinlock_t *ptl = hugetlb_pte_lockptr(hpte);
                                                 ^~~~
   include/linux/hugetlb.h:1306:53: note: passing argument to parameter 'hpte' here
   spinlock_t *hugetlb_pte_lockptr(struct hugetlb_pte *hpte)
                                                       ^
   include/linux/hugetlb.h:1321:56: warning: declaration of 'struct hugetlb_pte' will not be visible outside of this function [-Wvisibility]
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
                                                          ^
   include/linux/hugetlb.h:1323:25: error: variable has incomplete type 'enum hugetlb_level'
                             enum hugetlb_level level)
                                                ^
   include/linux/hugetlb.h:1275:20: note: forward declaration of 'enum hugetlb_level'
   static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
                      ^
   include/linux/hugetlb.h:1325:2: error: call to undeclared function '__hugetlb_pte_populate'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           __hugetlb_pte_populate(hpte, ptep, shift, level,
           ^
   include/linux/hugetlb.h:1325:2: note: did you mean 'hugetlb_pte_populate'?
   include/linux/hugetlb.h:1321:6: note: 'hugetlb_pte_populate' declared here
   void hugetlb_pte_populate(struct mm_struct *mm, struct hugetlb_pte *hpte,
        ^
   In file included from fs/proc/meminfo.c:7:
   include/linux/mman.h:153:9: warning: division by zero is undefined [-Wdivision-by-zero]
                  _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/mman.h:132:21: note: expanded from macro '_calc_vm_trans'
      : ((x) & (bit1)) / ((bit1) / (bit2))))
                       ^ ~~~~~~~~~~~~~~~~~
   include/linux/mman.h:154:9: warning: division by zero is undefined [-Wdivision-by-zero]
                  _calc_vm_trans(flags, MAP_SYNC,       VM_SYNC      ) |
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/mman.h:132:21: note: expanded from macro '_calc_vm_trans'
      : ((x) & (bit1)) / ((bit1) / (bit2))))
                       ^ ~~~~~~~~~~~~~~~~~
   fs/proc/meminfo.c:22:28: warning: no previous prototype for function 'arch_report_meminfo' [-Wmissing-prototypes]
   void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
                              ^
   fs/proc/meminfo.c:22:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
   ^
   static 
   6 warnings and 6 errors generated.


vim +1275 include/linux/hugetlb.h

  1274	
> 1275	static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
  1276	{
> 1277		return HUGETLB_LEVEL_PTE;
  1278	}
  1279	#endif	/* CONFIG_HUGETLB_PAGE */
  1280
Peter Xu Jan. 11, 2023, 9:51 p.m. UTC | #3
On Thu, Jan 05, 2023 at 10:18:11AM +0000, James Houghton wrote:

[...]

> +static int hugetlb_hgm_walk_uninit(struct hugetlb_pte *hpte,

Nitpick on the name: the "uninit" can be misread into pairing with some
other "init()" calls..

How about just call it hugetlb_hgm_walk (since it's the higher level API
comparing to the existing one)?  Then the existing hugetlb_hgm_walk can be
called hugetlb_hgm_do_walk/__hugetlb_hgm_walk since it's one level down.

> +				   pte_t *ptep,
> +				   struct vm_area_struct *vma,
> +				   unsigned long addr,
> +				   unsigned long target_sz,
> +				   bool alloc)
> +{
> +	struct hstate *h = hstate_vma(vma);
> +
> +	hugetlb_pte_populate(vma->vm_mm, hpte, ptep, huge_page_shift(h),
> +			     hpage_size_to_level(huge_page_size(h)));

Another nitpick on name: I remembered we used to reach a consensus of using
hugetlb_pte_init before?  Can we still avoid the word "populate" (if "init"
is not suitable since it can be updated during stepping, how about "setup")?

[...]

> +int hugetlb_walk_step(struct mm_struct *mm, struct hugetlb_pte *hpte,
> +		      unsigned long addr, unsigned long sz)
> +{
> +	pte_t *ptep;
> +	spinlock_t *ptl;
> +
> +	switch (hpte->level) {
> +	case HUGETLB_LEVEL_PUD:
> +		ptep = (pte_t *)hugetlb_alloc_pmd(mm, hpte, addr);
> +		if (IS_ERR(ptep))
> +			return PTR_ERR(ptep);
> +		hugetlb_pte_populate(mm, hpte, ptep, PMD_SHIFT,
> +				     HUGETLB_LEVEL_PMD);
> +		break;
> +	case HUGETLB_LEVEL_PMD:
> +		ptep = hugetlb_alloc_pte(mm, hpte, addr);
> +		if (IS_ERR(ptep))
> +			return PTR_ERR(ptep);
> +		ptl = pte_lockptr(mm, (pmd_t *)hpte->ptep);
> +		__hugetlb_pte_populate(hpte, ptep, PAGE_SHIFT,
> +				       HUGETLB_LEVEL_PTE, ptl);
> +		hpte->ptl = ptl;

This line seems to be superfluous (even if benign).

> +		break;
> +	default:
> +		WARN_ONCE(1, "%s: got invalid level: %d (shift: %d)\n",
> +				__func__, hpte->level, hpte->shift);
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
>  /*
>   * Return a mask that can be used to update an address to the last huge
>   * page in a page table page mapping size.  Used to skip non-present
> -- 
> 2.39.0.314.g84b9a713c41-goog
>
James Houghton Jan. 12, 2023, 1:38 p.m. UTC | #4
On Wed, Jan 11, 2023 at 4:51 PM Peter Xu <peterx@redhat.com> wrote:
>
> On Thu, Jan 05, 2023 at 10:18:11AM +0000, James Houghton wrote:
>
> [...]
>
> > +static int hugetlb_hgm_walk_uninit(struct hugetlb_pte *hpte,
>
> Nitpick on the name: the "uninit" can be misread into pairing with some
> other "init()" calls..
>
> How about just call it hugetlb_hgm_walk (since it's the higher level API
> comparing to the existing one)?  Then the existing hugetlb_hgm_walk can be
> called hugetlb_hgm_do_walk/__hugetlb_hgm_walk since it's one level down.
>
> > +                                pte_t *ptep,
> > +                                struct vm_area_struct *vma,
> > +                                unsigned long addr,
> > +                                unsigned long target_sz,
> > +                                bool alloc)
> > +{
> > +     struct hstate *h = hstate_vma(vma);
> > +
> > +     hugetlb_pte_populate(vma->vm_mm, hpte, ptep, huge_page_shift(h),
> > +                          hpage_size_to_level(huge_page_size(h)));
>
> Another nitpick on name: I remembered we used to reach a consensus of using
> hugetlb_pte_init before?  Can we still avoid the word "populate" (if "init"
> is not suitable since it can be updated during stepping, how about "setup")?

Right, we did talk about this, sorry. Ok I'll go ahead with this name change.
- hugetlb_hgm_walk => __hugetlb_hgm_walk
- hugetlb_hgm_walk_uninit => hugetlb_hgm_walk
- [__,]hugetlb_pte_populate => [__,]hugetlb_pte_init

>
> [...]
>
> > +int hugetlb_walk_step(struct mm_struct *mm, struct hugetlb_pte *hpte,
> > +                   unsigned long addr, unsigned long sz)
> > +{
> > +     pte_t *ptep;
> > +     spinlock_t *ptl;
> > +
> > +     switch (hpte->level) {
> > +     case HUGETLB_LEVEL_PUD:
> > +             ptep = (pte_t *)hugetlb_alloc_pmd(mm, hpte, addr);
> > +             if (IS_ERR(ptep))
> > +                     return PTR_ERR(ptep);
> > +             hugetlb_pte_populate(mm, hpte, ptep, PMD_SHIFT,
> > +                                  HUGETLB_LEVEL_PMD);
> > +             break;
> > +     case HUGETLB_LEVEL_PMD:
> > +             ptep = hugetlb_alloc_pte(mm, hpte, addr);
> > +             if (IS_ERR(ptep))
> > +                     return PTR_ERR(ptep);
> > +             ptl = pte_lockptr(mm, (pmd_t *)hpte->ptep);
> > +             __hugetlb_pte_populate(hpte, ptep, PAGE_SHIFT,
> > +                                    HUGETLB_LEVEL_PTE, ptl);
> > +             hpte->ptl = ptl;
>
> This line seems to be superfluous (even if benign).

Nice catch! It shouldn't be there; I accidentally left it in when I
changed how `ptl` was handled.

Thanks Peter!
diff mbox series

Patch

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ad9d19f0d1b9..2fcd8f313628 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -239,6 +239,14 @@  u32 hugetlb_fault_mutex_hash(struct address_space *mapping, pgoff_t idx);
 pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long addr, pud_t *pud);
 
+int hugetlb_full_walk(struct hugetlb_pte *hpte, struct vm_area_struct *vma,
+		      unsigned long addr);
+void hugetlb_full_walk_continue(struct hugetlb_pte *hpte,
+				struct vm_area_struct *vma, unsigned long addr);
+int hugetlb_full_walk_alloc(struct hugetlb_pte *hpte,
+			    struct vm_area_struct *vma, unsigned long addr,
+			    unsigned long target_sz);
+
 struct address_space *hugetlb_page_mapping_lock_write(struct page *hpage);
 
 extern int sysctl_hugetlb_shm_group;
@@ -288,6 +296,8 @@  pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 pte_t *huge_pte_offset(struct mm_struct *mm,
 		       unsigned long addr, unsigned long sz);
 unsigned long hugetlb_mask_last_page(struct hstate *h);
+int hugetlb_walk_step(struct mm_struct *mm, struct hugetlb_pte *hpte,
+		      unsigned long addr, unsigned long sz);
 int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma,
 				unsigned long addr, pte_t *ptep);
 void adjust_range_if_pmd_sharing_possible(struct vm_area_struct *vma,
@@ -1067,6 +1077,8 @@  void hugetlb_register_node(struct node *node);
 void hugetlb_unregister_node(struct node *node);
 #endif
 
+enum hugetlb_level hpage_size_to_level(unsigned long sz);
+
 #else	/* CONFIG_HUGETLB_PAGE */
 struct hstate {};
 
@@ -1259,6 +1271,11 @@  static inline void hugetlb_register_node(struct node *node)
 static inline void hugetlb_unregister_node(struct node *node)
 {
 }
+
+static inline enum hugetlb_level hpage_size_to_level(unsigned long sz)
+{
+	return HUGETLB_LEVEL_PTE;
+}
 #endif	/* CONFIG_HUGETLB_PAGE */
 
 #ifdef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING
@@ -1333,12 +1350,8 @@  __vma_has_hugetlb_vma_lock(struct vm_area_struct *vma)
 	return (vma->vm_flags & VM_MAYSHARE) && vma->vm_private_data;
 }
 
-/*
- * Safe version of huge_pte_offset() to check the locks.  See comments
- * above huge_pte_offset().
- */
-static inline pte_t *
-hugetlb_walk(struct vm_area_struct *vma, unsigned long addr, unsigned long sz)
+static inline void
+hugetlb_walk_lock_check(struct vm_area_struct *vma)
 {
 #if defined(CONFIG_HUGETLB_PAGE) && \
 	defined(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && defined(CONFIG_LOCKDEP)
@@ -1360,6 +1373,16 @@  hugetlb_walk(struct vm_area_struct *vma, unsigned long addr, unsigned long sz)
 			     !lockdep_is_held(
 				 &vma->vm_file->f_mapping->i_mmap_rwsem));
 #endif
+}
+
+/*
+ * Safe version of huge_pte_offset() to check the locks.  See comments
+ * above huge_pte_offset().
+ */
+static inline pte_t *
+hugetlb_walk(struct vm_area_struct *vma, unsigned long addr, unsigned long sz)
+{
+	hugetlb_walk_lock_check(vma);
 	return huge_pte_offset(vma->vm_mm, addr, sz);
 }
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2160cbaf3311..aa8e59cbca69 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -94,6 +94,29 @@  static int hugetlb_acct_memory(struct hstate *h, long delta);
 static void hugetlb_vma_lock_free(struct vm_area_struct *vma);
 static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
 
+/*
+ * hpage_size_to_level() - convert @sz to the corresponding page table level
+ *
+ * @sz must be less than or equal to a valid hugepage size.
+ */
+enum hugetlb_level hpage_size_to_level(unsigned long sz)
+{
+	/*
+	 * We order the conditionals from smallest to largest to pick the
+	 * smallest level when multiple levels have the same size (i.e.,
+	 * when levels are folded).
+	 */
+	if (sz < PMD_SIZE)
+		return HUGETLB_LEVEL_PTE;
+	if (sz < PUD_SIZE)
+		return HUGETLB_LEVEL_PMD;
+	if (sz < P4D_SIZE)
+		return HUGETLB_LEVEL_PUD;
+	if (sz < PGDIR_SIZE)
+		return HUGETLB_LEVEL_P4D;
+	return HUGETLB_LEVEL_PGD;
+}
+
 static inline bool subpool_is_free(struct hugepage_subpool *spool)
 {
 	if (spool->count)
@@ -7276,6 +7299,153 @@  bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr)
 }
 #endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */
 
+/* hugetlb_hgm_walk - walks a high-granularity HugeTLB page table to resolve
+ * the page table entry for @addr. We might allocate new PTEs.
+ *
+ * @hpte must always be pointing at an hstate-level PTE or deeper.
+ *
+ * This function will never walk further if it encounters a PTE of a size
+ * less than or equal to @sz.
+ *
+ * @alloc determines what we do when we encounter an empty PTE. If false,
+ * we stop walking. If true and @sz is less than the current PTE's size,
+ * we make that PTE point to the next level down, going until @sz is the same
+ * as our current PTE.
+ *
+ * If @alloc is false and @sz is PAGE_SIZE, this function will always
+ * succeed, but that does not guarantee that hugetlb_pte_size(hpte) is @sz.
+ *
+ * Return:
+ *	-ENOMEM if we couldn't allocate new PTEs.
+ *	-EEXIST if the caller wanted to walk further than a migration PTE,
+ *		poison PTE, or a PTE marker. The caller needs to manually deal
+ *		with this scenario.
+ *	-EINVAL if called with invalid arguments (@sz invalid, @hpte not
+ *		initialized).
+ *	0 otherwise.
+ *
+ *	Even if this function fails, @hpte is guaranteed to always remain
+ *	valid.
+ */
+static int hugetlb_hgm_walk(struct mm_struct *mm, struct vm_area_struct *vma,
+			    struct hugetlb_pte *hpte, unsigned long addr,
+			    unsigned long sz, bool alloc)
+{
+	int ret = 0;
+	pte_t pte;
+
+	if (WARN_ON_ONCE(sz < PAGE_SIZE))
+		return -EINVAL;
+
+	if (WARN_ON_ONCE(!hpte->ptep))
+		return -EINVAL;
+
+	/* We have the same synchronization requirements as hugetlb_walk. */
+	hugetlb_walk_lock_check(vma);
+
+	while (hugetlb_pte_size(hpte) > sz && !ret) {
+		pte = huge_ptep_get(hpte->ptep);
+		if (!pte_present(pte)) {
+			if (!alloc)
+				return 0;
+			if (unlikely(!huge_pte_none(pte)))
+				return -EEXIST;
+		} else if (hugetlb_pte_present_leaf(hpte, pte))
+			return 0;
+		ret = hugetlb_walk_step(mm, hpte, addr, sz);
+	}
+
+	return ret;
+}
+
+static int hugetlb_hgm_walk_uninit(struct hugetlb_pte *hpte,
+				   pte_t *ptep,
+				   struct vm_area_struct *vma,
+				   unsigned long addr,
+				   unsigned long target_sz,
+				   bool alloc)
+{
+	struct hstate *h = hstate_vma(vma);
+
+	hugetlb_pte_populate(vma->vm_mm, hpte, ptep, huge_page_shift(h),
+			     hpage_size_to_level(huge_page_size(h)));
+	return hugetlb_hgm_walk(vma->vm_mm, vma, hpte, addr, target_sz,
+				alloc);
+}
+
+/*
+ * hugetlb_full_walk_continue - continue a high-granularity page-table walk.
+ *
+ * If a user has a valid @hpte but knows that @hpte is not a leaf, they can
+ * attempt to continue walking by calling this function.
+ *
+ * This function may never fail, but @hpte might not change.
+ *
+ * If @hpte is not valid, then this function is a no-op.
+ */
+void hugetlb_full_walk_continue(struct hugetlb_pte *hpte,
+				struct vm_area_struct *vma,
+				unsigned long addr)
+{
+	/* hugetlb_hgm_walk will never fail with these arguments. */
+	WARN_ON_ONCE(hugetlb_hgm_walk(vma->vm_mm, vma, hpte, addr,
+				PAGE_SIZE, false));
+}
+
+/*
+ * hugetlb_full_walk - do a high-granularity page-table walk; never allocate.
+ *
+ * This function can only fail if we find that the hstate-level PTE is not
+ * allocated. Callers can take advantage of this fact to skip address regions
+ * that cannot be mapped in that case.
+ *
+ * If this function succeeds, @hpte is guaranteed to be valid.
+ */
+int hugetlb_full_walk(struct hugetlb_pte *hpte,
+		      struct vm_area_struct *vma,
+		      unsigned long addr)
+{
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+	/*
+	 * We must mask the address appropriately so that we pick up the first
+	 * PTE in a contiguous group.
+	 */
+	pte_t *ptep = hugetlb_walk(vma, addr & huge_page_mask(h), sz);
+
+	if (!ptep)
+		return -ENOMEM;
+
+	/* hugetlb_hgm_walk_uninit will never fail with these arguments. */
+	WARN_ON_ONCE(hugetlb_hgm_walk_uninit(hpte, ptep, vma, addr,
+				PAGE_SIZE, false));
+	return 0;
+}
+
+/*
+ * hugetlb_full_walk_alloc - do a high-granularity walk, potentially allocate
+ *	new PTEs.
+ */
+int hugetlb_full_walk_alloc(struct hugetlb_pte *hpte,
+				   struct vm_area_struct *vma,
+				   unsigned long addr,
+				   unsigned long target_sz)
+{
+	struct hstate *h = hstate_vma(vma);
+	unsigned long sz = huge_page_size(h);
+	/*
+	 * We must mask the address appropriately so that we pick up the first
+	 * PTE in a contiguous group.
+	 */
+	pte_t *ptep = huge_pte_alloc(vma->vm_mm, vma, addr & huge_page_mask(h),
+				     sz);
+
+	if (!ptep)
+		return -ENOMEM;
+
+	return hugetlb_hgm_walk_uninit(hpte, ptep, vma, addr, target_sz, true);
+}
+
 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long addr, unsigned long sz)
@@ -7343,6 +7513,49 @@  pte_t *huge_pte_offset(struct mm_struct *mm,
 	return (pte_t *)pmd;
 }
 
+/*
+ * hugetlb_walk_step() - Walk the page table one step to resolve the page
+ * (hugepage or subpage) entry at address @addr.
+ *
+ * @sz always points at the final target PTE size (e.g. PAGE_SIZE for the
+ * lowest level PTE).
+ *
+ * @hpte will always remain valid, even if this function fails.
+ *
+ * Architectures that implement this function must ensure that if @hpte does
+ * not change levels, then its PTL must also stay the same.
+ */
+int hugetlb_walk_step(struct mm_struct *mm, struct hugetlb_pte *hpte,
+		      unsigned long addr, unsigned long sz)
+{
+	pte_t *ptep;
+	spinlock_t *ptl;
+
+	switch (hpte->level) {
+	case HUGETLB_LEVEL_PUD:
+		ptep = (pte_t *)hugetlb_alloc_pmd(mm, hpte, addr);
+		if (IS_ERR(ptep))
+			return PTR_ERR(ptep);
+		hugetlb_pte_populate(mm, hpte, ptep, PMD_SHIFT,
+				     HUGETLB_LEVEL_PMD);
+		break;
+	case HUGETLB_LEVEL_PMD:
+		ptep = hugetlb_alloc_pte(mm, hpte, addr);
+		if (IS_ERR(ptep))
+			return PTR_ERR(ptep);
+		ptl = pte_lockptr(mm, (pmd_t *)hpte->ptep);
+		__hugetlb_pte_populate(hpte, ptep, PAGE_SHIFT,
+				       HUGETLB_LEVEL_PTE, ptl);
+		hpte->ptl = ptl;
+		break;
+	default:
+		WARN_ONCE(1, "%s: got invalid level: %d (shift: %d)\n",
+				__func__, hpte->level, hpte->shift);
+		return -EINVAL;
+	}
+	return 0;
+}
+
 /*
  * Return a mask that can be used to update an address to the last huge
  * page in a page table page mapping size.  Used to skip non-present