[PATCH v2 0/4] mm: hugetlb: fix CMA-related issues

[Qi Zheng <qi.zheng@linux.dev>]

From: Qi Zheng <zhengqi.arch@bytedance.com>

Hi all,

This series fixes four CMA-related issues in HugeTLB reservation,
long-term pinning and allocation:

 - Avoid ineffective CMA reservations on 32-bit x86 kernels running on
   CPUs that advertise 1 GiB page support.
 - Allow long-term pins of explicitly CMA-allocated HugeTLB folios,
   which already own their CMA bitmap ranges.
 - Preserve the caller's GFP mask when allocating from CMA.
 - Enforce cpuset restrictions on gigantic surplus allocations while
   preserving memory policy semantics.

Changes in v2:
 - Replace the PF_MEMALLOC_PIN allocation restriction with a GUP exception
   for HugeTLB folios marked HPG_cma. (suggested by Muchun Song)
 - Pass the caller's GFP mask through cma_alloc_frozen_compound() instead
   of skipping CMA when direct reclaim is disallowed.
   (suggested by sashiko)
 - Remove unnecessary revalidation of successfully allocated folios after
   cpuset changes. Retry only failed allocations.
   (pointed by Jose A. Perez de Azpillaga)
 - collect Reviewed-by and Acked-by.
 - Rebase onto next-20261104.

Qi Zheng (4):
  x86: hugetlb: disable default CMA reservations on 32-bit kernel
  mm: gup: allow long-term pins of CMA-allocated HugeTLB folios
  mm: hugetlb: fix GFP mask propagation to CMA
  mm: hugetlb: fix cpuset violations in gigantic surplus allocations

 arch/x86/mm/hugetlbpage.c |  2 +-
 include/linux/cma.h       |  2 +-
 include/linux/mm.h        | 29 +----------------------------
 mm/cma.c                  |  4 ++--
 mm/gup.c                  | 31 +++++++++++++++++++++++++++++++
 mm/hugetlb.c              | 25 ++++++++++++++++++-------
 mm/hugetlb_cma.c          |  4 ++--
 7 files changed, 56 insertions(+), 41 deletions(-)


base-commit: 8b7179210b22f8e48a82c5ceacb9d56a9c4cfec4
-- 
2.54.0