[PATCH v8 0/4] Fix free/allocation of runtime gigantic pages

Wed Mar 27 17:36:22 AEDT 2019

This 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 v8:                                                                   
  This (hopefully last) version is rebased against v5.1-rc2 so that              
  it takes into account https://patchwork.ozlabs.org/patch/1047003/.             
  This version:                                                                  
  - factorizes gigantic_page_runtime_supported such as suggested                 
    by Christophe.                                                               
  - fix checkpath warning regarding the use of 'extern'                          
  - fix s390 build that does not include asm-generic/hugetlb.h                   
  And note that I did not add the reviewed-by and acked-by received in v6        
  since the patch differs a little.                                              

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 |  5 +-
 arch/powerpc/platforms/Kconfig.cputype       |  2 +-
 arch/s390/Kconfig                            |  2 +-
 arch/s390/include/asm/hugetlb.h              |  8 +--
 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                |  7 +++
 include/linux/gfp.h                          |  4 +-
 mm/Kconfig                                   |  3 ++
 mm/hugetlb.c                                 | 54 ++++++++++++++------
 mm/page_alloc.c                              |  7 ++-
 16 files changed, 67 insertions(+), 41 deletions(-)

-- 
2.20.1