[PATCH v4 0/4] Clean up hugetlb boot command line processing

[Mike Kravetz]

v4 -
   Fixed huge page order definitions for arm64 (Qian Cai)
   Removed hugepages_supported() checks in command line processing as
     powerpc does not set hugepages_supported until later in boot (Sandipan)
   Added Acks, Reviews and Tested (Will, Gerald, Anders, Sandipan)

v3 -
   Used weak attribute method of defining arch_hugetlb_valid_size.
     This eliminates changes to arch specific hugetlb.h files (Peter)
   Updated documentation (Peter, Randy)
   Fixed handling of implicitly specified gigantic page preallocation
     in existing code and removed documentation of such.  There is now
     no difference between handling of gigantic and non-gigantic pages.
     (Peter, Nitesh).
     This requires the most review as there is a small change to
     undocumented behavior.  See patch 4 commit message for details.
   Added Acks and Reviews (Mina, Peter)

v2 -
   Fix build errors with patch 1 (Will)
   Change arch_hugetlb_valid_size arg to unsigned long and remove
     irrelevant 'extern' keyword (Christophe)
   Documentation and other misc changes (Randy, Christophe, Mina)
   Do not process command line options if !hugepages_supported()
     (Dave, but it sounds like we may want to additional changes to
      hugepages_supported() for x86?  If that is needed I would prefer
      a separate patch.)

Longpeng(Mike) reported a weird message from hugetlb command line processing
and proposed a solution [1].  While the proposed patch does address the
specific issue, there are other related issues in command line processing.
As hugetlbfs evolved, updates to command line processing have been made to
meet immediate needs and not necessarily in a coordinated manner.  The result
is that some processing is done in arch specific code, some is done in arch
independent code and coordination is problematic.  Semantics can vary between
architectures.

The patch series does the following:
- Define arch specific arch_hugetlb_valid_size routine used to validate
  passed huge page sizes.
- Move hugepagesz= command line parsing out of arch specific code and into
  an arch independent routine.
- Clean up command line processing to follow desired semantics and
  document those semantics.

[1] https://lore.kernel.org/linux-mm/20200305033014.1152-1-longpeng2@xxxxxxxxxx

Mike Kravetz (4):
  hugetlbfs: add arch_hugetlb_valid_size
  hugetlbfs: move hugepagesz= parsing to arch independent code
  hugetlbfs: remove hugetlb_add_hstate() warning for existing hstate
  hugetlbfs: clean up command line processing

 .../admin-guide/kernel-parameters.txt         |  40 ++--
 Documentation/admin-guide/mm/hugetlbpage.rst  |  35 ++++
 arch/arm64/mm/hugetlbpage.c                   |  30 +--
 arch/powerpc/mm/hugetlbpage.c                 |  30 +--
 arch/riscv/mm/hugetlbpage.c                   |  24 +--
 arch/s390/mm/hugetlbpage.c                    |  24 +--
 arch/sparc/mm/init_64.c                       |  43 +----
 arch/x86/mm/hugetlbpage.c                     |  23 +--
 include/linux/hugetlb.h                       |   2 +-
 mm/hugetlb.c                                  | 180 ++++++++++++++----
 10 files changed, 260 insertions(+), 171 deletions(-)

-- 
2.25.4