[RFC PATCH 00/18] use struct ptdesc to replace pgtable_t

[Alex Shi]

BTW, the patchset based on the latest git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm mm-unstable branch.

On 7/30/24 2:46 PM, alexs at kernel.org wrote:
> From: Alex Shi <alexs at kernel.org>
> 
> We have struct ptdesc for page table descriptor a year ago, but it
> has no much usages in kernel, while pgtable_t is used widely.
> 
> The pgtable_t is typedefed as 'pte_t *' in sparc, s390, powerpc and m68k
> except SUN3, others archs are all same as 'struct page *'.
> 
> These blocks the conception and code update for page table descriptor to
> struct ptdesc.
> 
> So, the simple idea to push the ptdesc conception forward is to update
> all pgtable_t by ptdesc or pte_t pointer. But this needs widely
> knowledges for most all of different archs. Common code change is easy
> for include/ and mm/ directory, but it's hard in all archs.
> 
> Thanks for intel LKP framework, I fixed most all of build issues except
> a bug on powerpc which reports a "struct ptdesc *" incompatible with 
> struct ptdesc *' pointer issue...
> 
> Another trouble is pmd_pgtable() conversion in the last patch.
> Maybe some of arch need define theirself own pmd_ptdesc()?
> 
> This patchset is immature, even except above 2 issues, I just tested
> virutal machine booting and kselftest mm on x86 and arm64.
> 
> Anyway any input are appreciated!
> 
> Thanks
> Alex
> 
> Alex Shi (18):
>   mm/pgtable: use ptdesc in pte_free_now/pte_free_defer
>   mm/pgtable: convert ptdesc.pmd_huge_pte to ptdesc pointer
>   fs/dax: use ptdesc in dax_pmd_load_hole
>   mm/thp: use ptdesc pointer in __do_huge_pmd_anonymous_page
>   mm/thp: use ptdesc in do_huge_pmd_anonymous_page
>   mm/thp: convert insert_pfn_pmd and its caller to use ptdesc
>   mm/thp: use ptdesc in copy_huge_pmd
>   mm/memory: use ptdesc in __pte_alloc
>   mm/pgtable: fully use ptdesc in pte_alloc_one series functions
>   mm/pgtable: pass ptdesc to pte_free()
>   mm/pgtable: introduce ptdesc_pfn and use ptdesc in free_pte_range()
>   mm/thp: pass ptdesc to set_huge_zero_folio function
>   mm/pgtable: return ptdesc pointer in pgtable_trans_huge_withdraw
>   mm/pgtable: use ptdesc in pgtable_trans_huge_deposit
>   mm/pgtable: pass ptdesc to pmd_populate
>   mm/pgtable: pass ptdesc to pmd_install
>   mm: convert vmf.prealloc_pte to struct ptdesc pointer
>   mm/pgtable: pass ptdesc in pte_free_defer
> 
>  arch/alpha/include/asm/pgalloc.h              |   4 +-
>  arch/arc/include/asm/pgalloc.h                |   4 +-
>  arch/arm/include/asm/pgalloc.h                |  13 +--
>  arch/arm/include/asm/tlb.h                    |   4 +-
>  arch/arm/mm/pgd.c                             |   2 +-
>  arch/arm64/include/asm/pgalloc.h              |   4 +-
>  arch/arm64/include/asm/tlb.h                  |   4 +-
>  arch/csky/include/asm/pgalloc.h               |   4 +-
>  arch/hexagon/include/asm/pgalloc.h            |   8 +-
>  arch/loongarch/include/asm/pgalloc.h          |   8 +-
>  arch/m68k/include/asm/motorola_pgalloc.h      |  12 +-
>  arch/m68k/include/asm/sun3_pgalloc.h          |   4 +-
>  arch/microblaze/include/asm/pgalloc.h         |   2 +-
>  arch/mips/include/asm/pgalloc.h               |   4 +-
>  arch/nios2/include/asm/pgalloc.h              |   4 +-
>  arch/openrisc/include/asm/pgalloc.h           |   8 +-
>  arch/parisc/include/asm/pgalloc.h             |   2 +-
>  arch/powerpc/include/asm/book3s/32/pgalloc.h  |   4 +-
>  arch/powerpc/include/asm/book3s/64/hash-4k.h  |   4 +-
>  arch/powerpc/include/asm/book3s/64/hash-64k.h |   4 +-
>  arch/powerpc/include/asm/book3s/64/pgalloc.h  |   4 +-
>  arch/powerpc/include/asm/book3s/64/pgtable.h  |   8 +-
>  arch/powerpc/include/asm/book3s/64/radix.h    |   4 +-
>  arch/powerpc/include/asm/pgalloc.h            |   8 +-
>  arch/powerpc/mm/book3s64/hash_pgtable.c       |  10 +-
>  arch/powerpc/mm/book3s64/radix_pgtable.c      |  10 +-
>  arch/riscv/include/asm/pgalloc.h              |   8 +-
>  arch/s390/include/asm/pgalloc.h               |   4 +-
>  arch/s390/include/asm/pgtable.h               |   4 +-
>  arch/s390/mm/pgalloc.c                        |   2 +-
>  arch/s390/mm/pgtable.c                        |  14 +--
>  arch/sh/include/asm/pgalloc.h                 |   4 +-
>  arch/sparc/include/asm/pgalloc_32.h           |   6 +-
>  arch/sparc/include/asm/pgalloc_64.h           |   2 +-
>  arch/sparc/include/asm/pgtable_64.h           |   4 +-
>  arch/sparc/mm/init_64.c                       |   2 +-
>  arch/sparc/mm/srmmu.c                         |   6 +-
>  arch/sparc/mm/tlb.c                           |  14 +--
>  arch/x86/include/asm/pgalloc.h                |  10 +-
>  arch/x86/mm/pgtable.c                         |   8 +-
>  arch/xtensa/include/asm/pgalloc.h             |  12 +-
>  fs/dax.c                                      |  14 +--
>  include/asm-generic/pgalloc.h                 |  10 +-
>  include/linux/mm.h                            |  16 ++-
>  include/linux/mm_types.h                      |   4 +-
>  include/linux/pgtable.h                       |   6 +-
>  mm/debug_vm_pgtable.c                         |   6 +-
>  mm/huge_memory.c                              | 103 +++++++++---------
>  mm/internal.h                                 |   2 +-
>  mm/khugepaged.c                               |  14 +--
>  mm/memory.c                                   |  15 +--
>  mm/mremap.c                                   |   2 +-
>  mm/pgtable-generic.c                          |  37 +++----
>  53 files changed, 240 insertions(+), 236 deletions(-)
>