[v7,0/4] Fix free/allocation of runtime gigantic pages

Message

Alexandre Ghiti March 17, 2019, 4:28 p.m. UTC

his series fixes sh and sparc that did not advertise their gigantic page
support and then were not able to allocate and free those pages at runtime.
It renames MEMORY_ISOLATION && COMPACTION || CMA condition into the more
accurate CONTIG_ALLOC, since it allows the definition of alloc_contig_range
function.
Finally, it then fixes the wrong definition of ARCH_HAS_GIGANTIC_PAGE config
that, without MEMORY_ISOLATION && COMPACTION || CMA defined, did not allow
architectures to free boottime allocated gigantic pages although unrelated.

Changes in v7:
  I thought gigantic page support was settled at compile time, but Aneesh
  and Michael have just come up with a patch proving me wrong for
  powerpc: https://patchwork.ozlabs.org/patch/1047003/. So this version:
  - reintroduces gigantic_page_supported renamed into
    gigantic_page_runtime_supported
  - reintroduces gigantic page page support corresponding checks (not
    everywhere though: set_max_huge_pages check was redundant with
    __nr_hugepages_store_common)
  - introduces the possibility for arch to override this function
    by using asm-generic/hugetlb.h current semantics although Aneesh
    proposed something else.

Changes in v6:
- Remove unnecessary goto since the fallthrough path does the same and is
  the 'normal' behaviour, as suggested by Dave Hensen
- Be more explicit in comment in set_max_huge_page: we return an error
  if alloc_contig_range is not defined and the user tries to allocate a
  gigantic page (we keep the same behaviour as before this patch), but we
  now let her free boottime gigantic page, as suggested by Dave Hensen
- Add Acked-by, thanks. 

Changes in v5:
- Fix bug in previous version thanks to Mike Kravetz
- Fix block comments that did not respect coding style thanks to Dave Hensen
- Define ARCH_HAS_GIGANTIC_PAGE only for sparc64 as advised by David Miller
- Factorize "def_bool" and "depends on" thanks to Vlastimil Babka

Changes in v4 as suggested by Dave Hensen:
- Split previous version into small patches
- Do not compile alloc_gigantic** functions for architectures that do not
  support those pages
- Define correct ARCH_HAS_GIGANTIC_PAGE in all arch that support them to avoid
  useless runtime check
- Add comment in set_max_huge_pages to explain that freeing is possible even
  without CONTIG_ALLOC defined
- Remove gigantic_page_supported function across all archs

Changes in v3 as suggested by Vlastimil Babka and Dave Hansen:
- config definition was wrong and is now in mm/Kconfig
- COMPACTION_CORE was renamed in CONTIG_ALLOC

Changes in v2 as suggested by Vlastimil Babka:
- Get rid of ARCH_HAS_GIGANTIC_PAGE
- Get rid of architecture specific gigantic_page_supported
- Factorize CMA or (MEMORY_ISOLATION && COMPACTION) into COMPACTION_CORE 

Alexandre Ghiti (4):
  sh: Advertise gigantic page support
  sparc: Advertise gigantic page support
  mm: Simplify MEMORY_ISOLATION && COMPACTION || CMA into CONTIG_ALLOC
  hugetlb: allow to free gigantic pages regardless of the configuration

 arch/arm64/Kconfig                           |  2 +-
 arch/arm64/include/asm/hugetlb.h             |  4 --
 arch/powerpc/include/asm/book3s/64/hugetlb.h |  7 ---
 arch/powerpc/platforms/Kconfig.cputype       |  2 +-
 arch/s390/Kconfig                            |  2 +-
 arch/s390/include/asm/hugetlb.h              |  3 --
 arch/sh/Kconfig                              |  1 +
 arch/sparc/Kconfig                           |  1 +
 arch/x86/Kconfig                             |  2 +-
 arch/x86/include/asm/hugetlb.h               |  4 --
 arch/x86/mm/hugetlbpage.c                    |  2 +-
 include/asm-generic/hugetlb.h                | 14 +++++
 include/linux/gfp.h                          |  4 +-
 mm/Kconfig                                   |  3 ++
 mm/hugetlb.c                                 | 54 ++++++++++++++------
 mm/page_alloc.c                              |  7 ++-
 16 files changed, 67 insertions(+), 45 deletions(-)