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mm: hugetlb: allocate frozen gigantic folio

From:  Kefeng Wang <wangkefeng.wang-AT-huawei.com>
To:  Andrew Morton <akpm-AT-linux-foundation.org>, David Hildenbrand <david-AT-redhat.com>, Oscar Salvador <osalvador-AT-suse.de>, Muchun Song <muchun.song-AT-linux.dev>, <linux-mm-AT-kvack.org>
Subject:  [PATCH v6 mm-new 0/6] mm: hugetlb: allocate frozen gigantic folio
Date:  Fri, 09 Jan 2026 17:31:30 +0800
Message-ID:  <20260109093136.1491549-1-wangkefeng.wang@huawei.com>
Cc:  <sidhartha.kumar-AT-oracle.com>, <jane.chu-AT-oracle.com>, Zi Yan <ziy-AT-nvidia.com>, Vlastimil Babka <vbabka-AT-suse.cz>, Brendan Jackman <jackmanb-AT-google.com>, Johannes Weiner <hannes-AT-cmpxchg.org>, Matthew Wilcox <willy-AT-infradead.org>, <broonie-AT-kernel.org>, Claudiu Beznea <claudiu.beznea.uj-AT-bp.renesas.com>, Kefeng Wang <wangkefeng.wang-AT-huawei.com>
Archive-link:  Article

Introduce alloc_contig_frozen_pages() and cma_alloc_frozen_compound()
which avoid atomic operation about page refcount, and then convert to
allocate frozen gigantic folio by the new helpers in hugetlb to cleanup
the alloc_gigantic_folio().

v6:
- fix crash due to wrong count passed to __cma_release_frozen() in
  patch5
  - thanks for the report from Mark/Claudiu/Dmitry and Zi's quickly fix
- besides hugetlb/hugetlb_cma tests, do more testing with cma_debug interface
- rebased on mm-new and collect RB

v5:
- address Zi Yan's comments 
  - convert one more VM_BUG_ON_PAGE to VM_WARN_ON_PAGE in split_page()
  - add a check to catch a tail page in free_contig_frozen_range()
  - remove __cma_release() and update patch3's changelog
  - put each page’s refcount in cma_release() and add find_cma_memrange()/
    __cma_release_frozen() to unify release path, which make the release
    pattern matches allocation patter
  - rename alloc_buddy_hugetlb_folio() and alloc_gigantic_folio() with frozen
- fix wrong node id passed to cma_alloc_frozen_compound() in
  hugetlb_cma_alloc_folio(), found by lkp
- collect ACK/RB from Zi Yan/Muchun
- rebased on mm-new

v4 RESEND:
- fix set_pages_refcounted() due to bad git-rebase
- rebased on next1215, also could be apply to mm-new.

v4:
- add VM_WARN_ON_PAGE and instead of VM_BUG_ON_PAGE in __split_page() 
- add back pr_debug part in __cma_release()
- rename alloc_contig_range_frozen to alloc_contig_frozen_range, and
  make alloc_contig_{range,pages} to only allocate non-compound pages,
  the free_contig_range() adjusted accordingly
- add set_pages_refcounted helper to reduce code duplication
- collect ACK

v3:
- Fix built warn/err, found by lkp test
- Address some David's comments,
  - Focus on frozen part and drop the optimization part
  - Rename split_non_compound_pages() to __split_pages()
  - Adding back debug print/WARN_ON if no cma range found or the
    pfn range of page is not full match the cma range.

v2:
- Optimize gigantic folio allocation speed
- Using HPAGE_PUD_ORDER in debug_vm_pgtable
- Address some David's comments,
  - kill folio_alloc_gigantic()
  - add generic cma_alloc_frozen{_compound}() instead of
    cma_{alloc,free}_folio


Kefeng Wang (6):
  mm: debug_vm_pgtable: add debug_vm_pgtable_free_huge_page()
  mm: page_alloc: add __split_page()
  mm: cma: kill cma_pages_valid()
  mm: page_alloc: add alloc_contig_frozen_{range,pages}()
  mm: cma: add cma_alloc_frozen{_compound}()
  mm: hugetlb: allocate frozen pages for gigantic allocation

 include/linux/cma.h     |  27 ++----
 include/linux/gfp.h     |  52 ++++------
 include/linux/mmdebug.h |  10 ++
 mm/cma.c                | 122 +++++++++++++----------
 mm/debug_vm_pgtable.c   |  38 ++++----
 mm/hugetlb.c            |  70 ++++----------
 mm/hugetlb_cma.c        |  29 +++---
 mm/hugetlb_cma.h        |  10 +-
 mm/internal.h           |  13 +++
 mm/page_alloc.c         | 209 ++++++++++++++++++++++++++++------------
 10 files changed, 326 insertions(+), 254 deletions(-)

-- 
2.27.0




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