diff mbox series

[04/33] mm: add utility functions for ptdesc

Message ID 20230417205048.15870-5-vishal.moola@gmail.com (mailing list archive)
State New
Headers show
Series Split ptdesc from struct page | expand

Commit Message

Vishal Moola April 17, 2023, 8:50 p.m. UTC
Introduce utility functions setting the foundation for ptdescs. These
will also assist in the splitting out of ptdesc from struct page.

ptdesc_alloc() is defined to allocate new ptdesc pages as compound
pages. This is to standardize ptdescs by allowing for one allocation
and one free function, in contrast to 2 allocation and 2 free functions.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
 include/asm-generic/tlb.h | 11 ++++++++++
 include/linux/mm.h        | 44 +++++++++++++++++++++++++++++++++++++++
 include/linux/pgtable.h   | 13 ++++++++++++
 3 files changed, 68 insertions(+)

Comments

kernel test robot April 18, 2023, 1:22 a.m. UTC | #1
Hi Vishal,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on s390/features powerpc/next powerpc/fixes geert-m68k/for-next geert-m68k/for-linus linus/master v6.3-rc7 next-20230417]
[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/Vishal-Moola-Oracle/s390-Use-_pt_s390_gaddr-for-gmap-address-tracking/20230418-045832
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230417205048.15870-5-vishal.moola%40gmail.com
patch subject: [PATCH 04/33] mm: add utility functions for ptdesc
config: sh-allmodconfig (https://download.01.org/0day-ci/archive/20230418/202304180913.p1BuXrBb-lkp@intel.com/config)
compiler: sh4-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/1b6f8137ca50a543ad2937092836635ca58c78ce
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Vishal-Moola-Oracle/s390-Use-_pt_s390_gaddr-for-gmap-address-tracking/20230418-045832
        git checkout 1b6f8137ca50a543ad2937092836635ca58c78ce
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sh prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304180913.p1BuXrBb-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   In file included from arch/sh/kernel/asm-offsets.c:14:
   include/linux/mm.h: In function 'virt_to_ptdesc':
>> include/linux/mm.h:2723:16: error: implicit declaration of function 'page_ptdesc' [-Werror=implicit-function-declaration]
    2723 |         return page_ptdesc(virt_to_head_page(x));
         |                ^~~~~~~~~~~
>> include/linux/mm.h:2723:16: warning: returning 'int' from a function with return type 'struct ptdesc *' makes pointer from integer without a cast [-Wint-conversion]
    2723 |         return page_ptdesc(virt_to_head_page(x));
         |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from arch/sh/include/asm/thread_info.h:13,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/sh/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:78,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/mm.h:7:
   include/linux/mm.h: In function 'ptdesc_to_virt':
>> include/linux/mm.h:2728:29: error: implicit declaration of function 'ptdesc_page'; did you mean 'pte_page'? [-Werror=implicit-function-declaration]
    2728 |         return page_to_virt(ptdesc_page(pt));
         |                             ^~~~~~~~~~~
   arch/sh/include/asm/page.h:139:27: note: in definition of macro '___va'
     139 | #define ___va(x)        ((x)+PAGE_OFFSET)
         |                           ^
   include/linux/mm.h:117:25: note: in expansion of macro '__va'
     117 | #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
         |                         ^~~~
   include/linux/mm.h:117:30: note: in expansion of macro 'PFN_PHYS'
     117 | #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
         |                              ^~~~~~~~
   include/asm-generic/memory_model.h:64:21: note: in expansion of macro '__page_to_pfn'
      64 | #define page_to_pfn __page_to_pfn
         |                     ^~~~~~~~~~~~~
   include/linux/mm.h:2728:16: note: in expansion of macro 'page_to_virt'
    2728 |         return page_to_virt(ptdesc_page(pt));
         |                ^~~~~~~~~~~~
>> include/asm-generic/memory_model.h:46:35: warning: initialization of 'const struct page *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
      46 | ({      const struct page *__pg = (pg);                         \
         |                                   ^
   arch/sh/include/asm/page.h:139:27: note: in definition of macro '___va'
     139 | #define ___va(x)        ((x)+PAGE_OFFSET)
         |                           ^
   include/linux/mm.h:117:25: note: in expansion of macro '__va'
     117 | #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
         |                         ^~~~
   include/linux/mm.h:117:30: note: in expansion of macro 'PFN_PHYS'
     117 | #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
         |                              ^~~~~~~~
   include/asm-generic/memory_model.h:64:21: note: in expansion of macro '__page_to_pfn'
      64 | #define page_to_pfn __page_to_pfn
         |                     ^~~~~~~~~~~~~
   include/linux/mm.h:117:39: note: in expansion of macro 'page_to_pfn'
     117 | #define page_to_virt(x) __va(PFN_PHYS(page_to_pfn(x)))
         |                                       ^~~~~~~~~~~
   include/linux/mm.h:2728:16: note: in expansion of macro 'page_to_virt'
    2728 |         return page_to_virt(ptdesc_page(pt));
         |                ^~~~~~~~~~~~
   include/linux/mm.h: In function 'ptdesc_address':
>> include/linux/mm.h:2733:30: error: implicit declaration of function 'ptdesc_folio'; did you mean 'page_folio'? [-Werror=implicit-function-declaration]
    2733 |         return folio_address(ptdesc_folio(pt));
         |                              ^~~~~~~~~~~~
         |                              page_folio
>> include/linux/mm.h:2733:30: warning: passing argument 1 of 'folio_address' makes pointer from integer without a cast [-Wint-conversion]
    2733 |         return folio_address(ptdesc_folio(pt));
         |                              ^~~~~~~~~~~~~~~~
         |                              |
         |                              int
   include/linux/mm.h:2151:55: note: expected 'const struct folio *' but argument is of type 'int'
    2151 | static inline void *folio_address(const struct folio *folio)
         |                                   ~~~~~~~~~~~~~~~~~~~~^~~~~
   include/linux/mm.h: In function 'ptdesc_is_reserved':
>> include/linux/mm.h:2738:36: warning: passing argument 1 of 'folio_test_reserved' makes pointer from integer without a cast [-Wint-conversion]
    2738 |         return folio_test_reserved(ptdesc_folio(pt));
         |                                    ^~~~~~~~~~~~~~~~
         |                                    |
         |                                    int
   In file included from include/linux/mmzone.h:23:
   include/linux/page-flags.h:375:62: note: expected 'struct folio *' but argument is of type 'int'
     375 | static __always_inline bool folio_test_##lname(struct folio *folio)     \
         |                                                ~~~~~~~~~~~~~~^~~~~
   include/linux/page-flags.h:423:9: note: in expansion of macro 'TESTPAGEFLAG'
     423 |         TESTPAGEFLAG(uname, lname, policy)                              \
         |         ^~~~~~~~~~~~
   include/linux/page-flags.h:494:1: note: in expansion of macro 'PAGEFLAG'
     494 | PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
         | ^~~~~~~~
   include/linux/mm.h: In function 'ptdesc_alloc':
   include/linux/mm.h:2745:16: warning: returning 'int' from a function with return type 'struct ptdesc *' makes pointer from integer without a cast [-Wint-conversion]
    2745 |         return page_ptdesc(page);
         |                ^~~~~~~~~~~~~~~~~
   include/linux/mm.h: In function 'ptdesc_free':
>> include/linux/mm.h:2750:29: warning: initialization of 'struct page *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    2750 |         struct page *page = ptdesc_page(pt);
         |                             ^~~~~~~~~~~
   include/linux/mm.h: In function 'free_reserved_ptdesc':
>> include/linux/mm.h:2988:28: warning: passing argument 1 of 'free_reserved_page' makes pointer from integer without a cast [-Wint-conversion]
    2988 |         free_reserved_page(ptdesc_page(pt));
         |                            ^~~~~~~~~~~~~~~
         |                            |
         |                            int
   include/linux/mm.h:2971:52: note: expected 'struct page *' but argument is of type 'int'
    2971 | static inline void free_reserved_page(struct page *page)
         |                                       ~~~~~~~~~~~~~^~~~
   cc1: some warnings being treated as errors
   make[2]: *** [scripts/Makefile.build:114: arch/sh/kernel/asm-offsets.s] Error 1
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:1286: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:226: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/page_ptdesc +2723 include/linux/mm.h

  2720	
  2721	static inline struct ptdesc *virt_to_ptdesc(const void *x)
  2722	{
> 2723		return page_ptdesc(virt_to_head_page(x));
  2724	}
  2725	
  2726	static inline void *ptdesc_to_virt(struct ptdesc *pt)
  2727	{
> 2728		return page_to_virt(ptdesc_page(pt));
  2729	}
  2730	
  2731	static inline void *ptdesc_address(struct ptdesc *pt)
  2732	{
> 2733		return folio_address(ptdesc_folio(pt));
  2734	}
  2735	
  2736	static inline bool ptdesc_is_reserved(struct ptdesc *pt)
  2737	{
> 2738		return folio_test_reserved(ptdesc_folio(pt));
  2739	}
  2740	
  2741	static inline struct ptdesc *ptdesc_alloc(gfp_t gfp, unsigned int order)
  2742	{
  2743		struct page *page = alloc_pages(gfp | __GFP_COMP, order);
  2744	
  2745		return page_ptdesc(page);
  2746	}
  2747	
  2748	static inline void ptdesc_free(struct ptdesc *pt)
  2749	{
> 2750		struct page *page = ptdesc_page(pt);
  2751	
  2752		__free_pages(page, compound_order(page));
  2753	}
  2754
Vernon Yang April 19, 2023, 1:33 p.m. UTC | #2
On Mon, Apr 17, 2023 at 01:50:19PM -0700, Vishal Moola wrote:
> Introduce utility functions setting the foundation for ptdescs. These
> will also assist in the splitting out of ptdesc from struct page.
>
> ptdesc_alloc() is defined to allocate new ptdesc pages as compound
> pages. This is to standardize ptdescs by allowing for one allocation
> and one free function, in contrast to 2 allocation and 2 free functions.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
>  include/asm-generic/tlb.h | 11 ++++++++++
>  include/linux/mm.h        | 44 +++++++++++++++++++++++++++++++++++++++
>  include/linux/pgtable.h   | 13 ++++++++++++
>  3 files changed, 68 insertions(+)
>
> diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
> index b46617207c93..6bade9e0e799 100644
> --- a/include/asm-generic/tlb.h
> +++ b/include/asm-generic/tlb.h
> @@ -481,6 +481,17 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
>  	return tlb_remove_page_size(tlb, page, PAGE_SIZE);
>  }
>
> +static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
> +{
> +	tlb_remove_table(tlb, pt);
> +}
> +
> +/* Like tlb_remove_ptdesc, but for page-like page directories. */
> +static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
> +{
> +	tlb_remove_page(tlb, ptdesc_page(pt));
> +}
> +
>  static inline void tlb_change_page_size(struct mmu_gather *tlb,
>  						     unsigned int page_size)
>  {
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index b18848ae7e22..ec3cbe2fa665 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2744,6 +2744,45 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
>  }
>  #endif /* CONFIG_MMU */
>
> +static inline struct ptdesc *virt_to_ptdesc(const void *x)
> +{
> +	return page_ptdesc(virt_to_head_page(x));
> +}
> +
> +static inline void *ptdesc_to_virt(struct ptdesc *pt)
> +{
> +	return page_to_virt(ptdesc_page(pt));
> +}
> +
> +static inline void *ptdesc_address(struct ptdesc *pt)
> +{
> +	return folio_address(ptdesc_folio(pt));
> +}
> +
> +static inline bool ptdesc_is_reserved(struct ptdesc *pt)
> +{
> +	return folio_test_reserved(ptdesc_folio(pt));
> +}
> +
> +static inline struct ptdesc *ptdesc_alloc(gfp_t gfp, unsigned int order)
> +{
> +	struct page *page = alloc_pages(gfp | __GFP_COMP, order);
> +
> +	return page_ptdesc(page);
> +}
> +
> +static inline void ptdesc_free(struct ptdesc *pt)
> +{
> +	struct page *page = ptdesc_page(pt);
> +
> +	__free_pages(page, compound_order(page));
> +}
> +
> +static inline void ptdesc_clear(void *x)
> +{
> +	clear_page(x);
> +}
> +
>  #if USE_SPLIT_PTE_PTLOCKS
>  #if ALLOC_SPLIT_PTLOCKS
>  void __init ptlock_cache_init(void);
> @@ -2970,6 +3009,11 @@ static inline void mark_page_reserved(struct page *page)
>  	adjust_managed_page_count(page, -1);
>  }
>
> +static inline void free_reserved_ptdesc(struct ptdesc *pt)
> +{
> +	free_reserved_page(ptdesc_page(pt));
> +}
> +
>  /*
>   * Default method to free all the __init memory into the buddy system.
>   * The freed pages will be poisoned with pattern "poison" if it's within
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 7cc6ea057ee9..7cd803aa38eb 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -97,6 +97,19 @@ TABLE_MATCH(ptl, ptl);
>  #undef TABLE_MATCH
>  static_assert(sizeof(struct ptdesc) <= sizeof(struct page));
>
> +#define ptdesc_page(pt)			(_Generic((pt),			\
> +	const struct ptdesc *:		(const struct page *)(pt),	\
> +	struct ptdesc *:		(struct page *)(pt)))
> +
> +#define ptdesc_folio(pt)		(_Generic((pt),			\
> +	const struct ptdesc *:		(const struct folio *)(pt),	\
> +	struct ptdesc *:		(struct folio *)(pt)))
> +
> +static inline struct ptdesc *page_ptdesc(struct page *page)
> +{
> +	return (struct ptdesc *)page;
> +}

Hi Vishal,

I'm a little curious, why is the page_ptdesc() using inline functions instead of macro?
If this is any magic, please tell me, thank you very much.

> +
>  /*
>   * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
>   *
>
> --
> 2.39.2
>
Vishal Moola April 19, 2023, 8:29 p.m. UTC | #3
On Wed, Apr 19, 2023 at 6:34 AM Vernon Yang <vernon2gm@gmail.com> wrote:
>
> On Mon, Apr 17, 2023 at 01:50:19PM -0700, Vishal Moola wrote:
> > Introduce utility functions setting the foundation for ptdescs. These
> > will also assist in the splitting out of ptdesc from struct page.
> >
> > ptdesc_alloc() is defined to allocate new ptdesc pages as compound
> > pages. This is to standardize ptdescs by allowing for one allocation
> > and one free function, in contrast to 2 allocation and 2 free functions.
> >
> > Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> > ---
> >  include/asm-generic/tlb.h | 11 ++++++++++
> >  include/linux/mm.h        | 44 +++++++++++++++++++++++++++++++++++++++
> >  include/linux/pgtable.h   | 13 ++++++++++++
> >  3 files changed, 68 insertions(+)
> >
> > diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
> > index b46617207c93..6bade9e0e799 100644
> > --- a/include/asm-generic/tlb.h
> > +++ b/include/asm-generic/tlb.h
> > @@ -481,6 +481,17 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
> >       return tlb_remove_page_size(tlb, page, PAGE_SIZE);
> >  }
> >
> > +static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
> > +{
> > +     tlb_remove_table(tlb, pt);
> > +}
> > +
> > +/* Like tlb_remove_ptdesc, but for page-like page directories. */
> > +static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
> > +{
> > +     tlb_remove_page(tlb, ptdesc_page(pt));
> > +}
> > +
> >  static inline void tlb_change_page_size(struct mmu_gather *tlb,
> >                                                    unsigned int page_size)
> >  {
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index b18848ae7e22..ec3cbe2fa665 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -2744,6 +2744,45 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
> >  }
> >  #endif /* CONFIG_MMU */
> >
> > +static inline struct ptdesc *virt_to_ptdesc(const void *x)
> > +{
> > +     return page_ptdesc(virt_to_head_page(x));
> > +}
> > +
> > +static inline void *ptdesc_to_virt(struct ptdesc *pt)
> > +{
> > +     return page_to_virt(ptdesc_page(pt));
> > +}
> > +
> > +static inline void *ptdesc_address(struct ptdesc *pt)
> > +{
> > +     return folio_address(ptdesc_folio(pt));
> > +}
> > +
> > +static inline bool ptdesc_is_reserved(struct ptdesc *pt)
> > +{
> > +     return folio_test_reserved(ptdesc_folio(pt));
> > +}
> > +
> > +static inline struct ptdesc *ptdesc_alloc(gfp_t gfp, unsigned int order)
> > +{
> > +     struct page *page = alloc_pages(gfp | __GFP_COMP, order);
> > +
> > +     return page_ptdesc(page);
> > +}
> > +
> > +static inline void ptdesc_free(struct ptdesc *pt)
> > +{
> > +     struct page *page = ptdesc_page(pt);
> > +
> > +     __free_pages(page, compound_order(page));
> > +}
> > +
> > +static inline void ptdesc_clear(void *x)
> > +{
> > +     clear_page(x);
> > +}
> > +
> >  #if USE_SPLIT_PTE_PTLOCKS
> >  #if ALLOC_SPLIT_PTLOCKS
> >  void __init ptlock_cache_init(void);
> > @@ -2970,6 +3009,11 @@ static inline void mark_page_reserved(struct page *page)
> >       adjust_managed_page_count(page, -1);
> >  }
> >
> > +static inline void free_reserved_ptdesc(struct ptdesc *pt)
> > +{
> > +     free_reserved_page(ptdesc_page(pt));
> > +}
> > +
> >  /*
> >   * Default method to free all the __init memory into the buddy system.
> >   * The freed pages will be poisoned with pattern "poison" if it's within
> > diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> > index 7cc6ea057ee9..7cd803aa38eb 100644
> > --- a/include/linux/pgtable.h
> > +++ b/include/linux/pgtable.h
> > @@ -97,6 +97,19 @@ TABLE_MATCH(ptl, ptl);
> >  #undef TABLE_MATCH
> >  static_assert(sizeof(struct ptdesc) <= sizeof(struct page));
> >
> > +#define ptdesc_page(pt)                      (_Generic((pt),                 \
> > +     const struct ptdesc *:          (const struct page *)(pt),      \
> > +     struct ptdesc *:                (struct page *)(pt)))
> > +
> > +#define ptdesc_folio(pt)             (_Generic((pt),                 \
> > +     const struct ptdesc *:          (const struct folio *)(pt),     \
> > +     struct ptdesc *:                (struct folio *)(pt)))
> > +
> > +static inline struct ptdesc *page_ptdesc(struct page *page)
> > +{
> > +     return (struct ptdesc *)page;
> > +}
>
> Hi Vishal,
>
> I'm a little curious, why is the page_ptdesc() using inline functions instead of macro?
> If this is any magic, please tell me, thank you very much.

No magic here, I was mainly basing it off Matthew's netmem
series. I'm not too clear on when to use macros vs inlines
myself :/.

If there's a benefit to having it be a macro let me
know and I can make that change in v2.
diff mbox series

Patch

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index b46617207c93..6bade9e0e799 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -481,6 +481,17 @@  static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 	return tlb_remove_page_size(tlb, page, PAGE_SIZE);
 }
 
+static inline void tlb_remove_ptdesc(struct mmu_gather *tlb, void *pt)
+{
+	tlb_remove_table(tlb, pt);
+}
+
+/* Like tlb_remove_ptdesc, but for page-like page directories. */
+static inline void tlb_remove_page_ptdesc(struct mmu_gather *tlb, struct ptdesc *pt)
+{
+	tlb_remove_page(tlb, ptdesc_page(pt));
+}
+
 static inline void tlb_change_page_size(struct mmu_gather *tlb,
 						     unsigned int page_size)
 {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b18848ae7e22..ec3cbe2fa665 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2744,6 +2744,45 @@  static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
 }
 #endif /* CONFIG_MMU */
 
+static inline struct ptdesc *virt_to_ptdesc(const void *x)
+{
+	return page_ptdesc(virt_to_head_page(x));
+}
+
+static inline void *ptdesc_to_virt(struct ptdesc *pt)
+{
+	return page_to_virt(ptdesc_page(pt));
+}
+
+static inline void *ptdesc_address(struct ptdesc *pt)
+{
+	return folio_address(ptdesc_folio(pt));
+}
+
+static inline bool ptdesc_is_reserved(struct ptdesc *pt)
+{
+	return folio_test_reserved(ptdesc_folio(pt));
+}
+
+static inline struct ptdesc *ptdesc_alloc(gfp_t gfp, unsigned int order)
+{
+	struct page *page = alloc_pages(gfp | __GFP_COMP, order);
+
+	return page_ptdesc(page);
+}
+
+static inline void ptdesc_free(struct ptdesc *pt)
+{
+	struct page *page = ptdesc_page(pt);
+
+	__free_pages(page, compound_order(page));
+}
+
+static inline void ptdesc_clear(void *x)
+{
+	clear_page(x);
+}
+
 #if USE_SPLIT_PTE_PTLOCKS
 #if ALLOC_SPLIT_PTLOCKS
 void __init ptlock_cache_init(void);
@@ -2970,6 +3009,11 @@  static inline void mark_page_reserved(struct page *page)
 	adjust_managed_page_count(page, -1);
 }
 
+static inline void free_reserved_ptdesc(struct ptdesc *pt)
+{
+	free_reserved_page(ptdesc_page(pt));
+}
+
 /*
  * Default method to free all the __init memory into the buddy system.
  * The freed pages will be poisoned with pattern "poison" if it's within
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 7cc6ea057ee9..7cd803aa38eb 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -97,6 +97,19 @@  TABLE_MATCH(ptl, ptl);
 #undef TABLE_MATCH
 static_assert(sizeof(struct ptdesc) <= sizeof(struct page));
 
+#define ptdesc_page(pt)			(_Generic((pt),			\
+	const struct ptdesc *:		(const struct page *)(pt),	\
+	struct ptdesc *:		(struct page *)(pt)))
+
+#define ptdesc_folio(pt)		(_Generic((pt),			\
+	const struct ptdesc *:		(const struct folio *)(pt),	\
+	struct ptdesc *:		(struct folio *)(pt)))
+
+static inline struct ptdesc *page_ptdesc(struct page *page)
+{
+	return (struct ptdesc *)page;
+}
+
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
  *