[PATCH 5.10.y 0/7] mm/hugetlb: fixes for PMD table sharing (incl. using mmu_gather)

["David Hildenbrand (Arm)" <david@kernel.org>]

Backport of [1] for 5.10. Backport notes are in the individual patches.

I found one bug in a previous backport, fix in patch #1.

I'm also including a cleanup/fix from Miaohe that makes backporting at
least a bit easier, followed by the fix from Jane.

Tested on x86-64 with the original reproducer.

[1] https://lore.kernel.org/linux-mm/20251223214037.580860-1-david@kernel.org/

Cc: Jane Chu <jane.chu@oracle.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jann Horn <jannh@google.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: James Houghton <jthoughton@google.com>

David Hildenbrand (Arm) (1):
  mm/hugetlb: fix skipping of unsharing of pmd page tables

David Hildenbrand (Red Hat) (4):
  mm/hugetlb: fix hugetlb_pmd_shared()
  mm/hugetlb: fix two comments related to huge_pmd_unshare()
  mm/rmap: fix two comments related to huge_pmd_unshare()
  mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables
    using mmu_gather

Jane Chu (1):
  mm/hugetlb: fix copy_hugetlb_page_range() to use ->pt_share_count

Miaohe Lin (1):
  mm/hugetlb: make detecting shared pte more reliable

 include/asm-generic/tlb.h |  77 +++++++++++++++++++-
 include/linux/hugetlb.h   |  17 +++--
 include/linux/mm_types.h  |   2 +
 mm/hugetlb.c              | 143 ++++++++++++++++++++------------------
 mm/mmu_gather.c           |  36 ++++++++++
 mm/rmap.c                 |  20 +++---
 6 files changed, 208 insertions(+), 87 deletions(-)

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2.43.0