[PATCH v4 0/3] mm: hugetlb: fix CMA-related issues

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

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

Hi all,

This series fixes three 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 the CMA memory.
 - Preserve the caller's GFP mask when allocating from CMA.

Changes in v4:
 - add comment to cma_alloc_frozen_compound().
   (suggested by Oscar Salvador)
 - collect Reviewed-by tag.
 - rebase onto next-20261110.

Changes in v3:
 - Drop the cpuset fix. A more comprehensive fix across the HugeTLB
   allocation paths will follow in a separate patchset.
 - Check for __GFP_COMP instead of adding it in
   cma_alloc_frozen_compound(), and leave __GFP_NOWARN to callers.
   (suggested by Oscar Salvador)
 - Clarify the CMA ownership comment in folio_is_longterm_pinnable().
   (suggested by Muchun Song)
 - Collect Reviewed-by and Acked-by tags.

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.

Thanks,
Qi

Qi Zheng (3):
  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

 arch/x86/mm/hugetlbpage.c |  2 +-
 include/linux/cma.h       |  2 +-
 include/linux/mm.h        | 29 +----------------------------
 mm/cma.c                  | 10 ++++++++--
 mm/gup.c                  | 31 +++++++++++++++++++++++++++++++
 mm/hugetlb_cma.c          |  4 ++--
 6 files changed, 44 insertions(+), 34 deletions(-)


base-commit: 793807ca13bf3072fc6d16ce6d90e9ab9beff2a5
-- 
2.54.0