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[1] https://lore.kernel.org/all/cover.1782538002.git.zhengqi.arch@bytedan= ce.com/ On 2 Jul 2026, at 12:21, Ackerley Tng via B4 Relay wrote: > Hi, > > The motivation for this patch series is guest_memfd, which would like > to use HugeTLB as a generic source of huge pages but not adopt > HugeTLB's reservation at mmap() time. > > By refactoring alloc_hugetlb_folio() and some dependent functions, > there is now an option to allocate HugeTLB folios without providing a > VMA. Specifically, HugeTLB allocation used to be dependent on the VMA > to > > 1. Look up reservations in the resv_map > 2. Get mpol, stored at vma->vm_policy > > This refactoring provides hugetlb_alloc_folio(), which focuses on just > the allocation itself, and associated memory and HugeTLB charging > (cgroups). alloc_hugetlb_folio() still handles reservations in the > resv_map and subpools. > > Regarding naming, I'm definitely open to alternative names :) I chose > hugetlb_alloc_folio() because I'm seeing this function as a general > allocation function that is provided by the HugeTLB subsystem (hence > the hugetlb_ prefix). I'm intending for alloc_hugetlb_folio() to be > later refactored as a static function for use just by HugeTLB, and > HugeTLBfs should probably use hugetlb_alloc_folio() directly. > > To see how hugetlb_alloc_folio() is used by guest_memfd, the most > recent patch series that uses this more generic HugeTLB allocation > routine is at [1], and a newer revision of that patch series is at > [2]. > > Independently of guest_memfd, I believe this change is useful in > simplifying alloc_hugetlb_folio(). alloc_hugetlb_folio() was so > coupled to a VMA that even HugeTLBfs allocates HugeTLB folios using a > pseudo-VMA. > > Testing: > > + libhugetlbfs tests pass > + ./tools/testing/selftests/mm/ksft_hugetlb.sh passes > > Andrew, thanks for nudging me to send a v4! > > Oscar, you mentioned that you wanted to do a closer review on v3, hope = you > find time to review v4 soon! > > Changes in this revision: > > + Define gfp within hugetlb_alloc_folio() instead of having it as a > parameter so users aren't able to override gfp arbitrarily as Oscar > requested. > + Addressed some of Sashiko's comments [4]. Some of the issues I didn't= address > were pre-existing issues. Since v3 of this series Sashiko was updated= to > actually send mails. I'd let Sashiko point them out again and then we= should > discuss those! > > [1] https://lore.kernel.org/all/cover.1747264138.git.ackerleytng@google= =2Ecom/T/ > [2] https://github.com/googleprodkernel/linux-cc/tree/wip-gmem-conversi= ons-hugetlb-restructuring-12-08-25 > [3] https://lore.kernel.org/all/agqaUcVp_hwH-VXr@localhost.localdomain/= > [4] https://sashiko.dev/#/patchset/20260518-hugetlb-open-up-v3-0-e14b30= 2477f8@google.com > > RFC v1: https://lore.kernel.org/all/bb35a69a-5be9-45f5-a557-1902487a1bc= 2@linux.dev/ > v2: https://lore.kernel.org/r/20260506-hugetlb-open-up-v2-0-826a0c5f28f= c@google.com > v3: https://lore.kernel.org/r/20260518-hugetlb-open-up-v3-0-e14b302477f= 8@google.com > > --- > Ackerley Tng (6): > mm: hugetlb: Consolidate interpretation of gbl_chg within alloc_h= ugetlb_folio() > mm: hugetlb: Move mpol interpretation out of alloc_buddy_hugetlb_= folio_with_mpol() > mm: hugetlb: Move mpol interpretation out of dequeue_hugetlb_foli= o_vma() > mm: hugetlb: Use error variable in alloc_hugetlb_folio > mm: hugetlb: Move mem_cgroup_charge_hugetlb() earlier in allocati= on > mm: hugetlb: Refactor out hugetlb_alloc_folio() > > include/linux/hugetlb.h | 18 +++ > include/uapi/linux/mempolicy.h | 2 +- > mm/hugetlb.c | 269 ++++++++++++++++++++++++---------= -------- > 3 files changed, 175 insertions(+), 114 deletions(-) > --- > base-commit: 4a50a141f05a8d1737661b19ee22ff8455b94409 > change-id: 20260504-hugetlb-open-up-eaba80571b09 > > Best regards, > -- > Ackerley Tng Best Regards, Yan, Zi