Re: [PATCH v2 00/13] mm: Some cleanups for page allocator APIs

[Vlastimil Babka (SUSE)]

+Cc Hao Ge for the "remove __GFP_NO_CODETAG" part

On 6/22/26 12:01, Brendan Jackman wrote:
> Some tweaks and cleanups for page allocator entrypoint and flags. This
> is motivated by preparation for __GFP_UNMAPPED [1] (which will probably
> become ALLOC_UNMAPPED in its next iteration), but all this is supposed
> to be an improvement to the codebase in its own right: unifying code
> paths, reducing API surface, and removing GFP flags.
> 
> [1] https://lore.kernel.org/all/20260320-page_alloc-unmapped-v2-0-28bf1bd54f41@xxxxxxxxxx/
> 
> This started with unifying  __alloc_frozen_pages[_nolock]_noprof() and
> expanded from there.
> 
> Unifying the nolock allocator entrypoint with the normal allocator
> entrypoint means adding an alloc_flags argument to the later (only
> exposed within mm/). This presents an opportunity to take advantage of
> that arg to remove some GFP flags, if we add that alloc_flags arg a bit
> more broadly to allocator entrypoints.
> 
> To distinguish between mm-internal and "public" allocator entrypoints,
> it makes sense to use the __ prefix. There are already some public APIs
> with that prefix. For *alloc_pages*, just removing those variants seems
> like a nice cleanup anyway, so do that. For get_free_pages, the "__"
> variant is the _only_ variant and it's very widely used, so it doesn't
> seem worthwhile to modify that. Therefore, scope this "__" change
> specifically to the *alloc_pages* API, which means we leave the
> *folio_alloc* API untouched too, even though that could probably be
> cleaned up if so desired.
> 
> Tested:
> 
> - KVM, mm, and BPF selftests in a QEMU VM
> 
> - kunit.py on x86_64
> 
> - For the ALLOC_NO_CODETAG bits I just booted a VM and read
>   /proc/allocinfo. I confirmed that if I remove ALLOC_NO_CODETAG, the
>   kernel crashes in early boot, so I was at least booting code that
>   depends on this logic.
> 
> I used Google's internal version of Antigravity (AI coding harness) to
> do the repetitive bits, those commits are marked with Assisted-by, the
> rest is manual.
> 
> Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx>
> ---
> Changes in v2:
> - Fixed up whitespace in nolock unification patch
> - Introduced ALLOC_DEFAULT to replace literal 0 for alloc_flags
> - All other patches are new
> - Link to v1: https://patch.msgid.link/20260617-alloc-trylock-v1-1-83fd7858832e@xxxxxxxxxx
> 
> ---
> Brendan Jackman (13):
>       mm/page_alloc: rename ALLOC_TRYLOCK -> ALLOC_NOLOCK
>       mm/page_alloc: some renames to clarify alloc_flags scopes
>       mm/page_alloc: unify __alloc_frozen_pages[_nolock]_noprof()
>       mm/page_alloc: relax GFP WARN in nolock allocs
>       perf/x86/intel: Use higher-level allocator
>       KVM: VMX: Use higher-level allocator
>       x86/virt: Use higher-level allocator
>       sgi-xp: Use higher-level allocator
>       net/funeth: Switch to higher-level allocator
>       mm: Remove __alloc_pages_node()
>       alloc_tag: Move to mm/
>       mm: Move __alloc_pages() to mm/internal.h
>       mm: remove __GFP_NO_CODETAG
> 
>  Documentation/admin-guide/cgroup-v1/cpusets.rst  |   2 +-
>  Documentation/admin-guide/mm/transhuge.rst       |   2 +-
>  MAINTAINERS                                      |   2 +-
>  arch/x86/events/intel/ds.c                       |   6 +-
>  arch/x86/kvm/vmx/vmx.c                           |   2 +-
>  arch/x86/virt/hw.c                               |   2 +-
>  drivers/misc/sgi-xp/xpc_uv.c                     |   2 +-
>  drivers/net/ethernet/fungible/funeth/funeth_rx.c |   2 +-
>  include/linux/gfp.h                              |  28 +--
>  lib/Makefile                                     |   1 -
>  mm/Makefile                                      |   1 +
>  {lib => mm}/alloc_tag.c                          |  18 +-
>  mm/compaction.c                                  |   4 +-
>  mm/hugetlb.c                                     |   3 +-
>  mm/internal.h                                    |  20 +-
>  mm/mempolicy.c                                   |  10 +-
>  mm/page_alloc.c                                  | 254 +++++++++++++----------
>  mm/page_frag_cache.c                             |   4 +-
>  mm/slub.c                                        |   6 +-
>  19 files changed, 193 insertions(+), 176 deletions(-)
> ---
> base-commit: cbe5256a15fc26f592efb037e528da54b2139ee5
> change-id: 20260617-alloc-trylock-14ad37dab337
> 
> Best regards,
> --  
> Brendan Jackman <jackmanb@xxxxxxxxxx>
>