linux.git/rust/kernel/alloc.rs, branch v6.18.21

Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-10-03T01:18:33+00:00

Pull MM updates from Andrew Morton:

 - "mm, swap: improve cluster scan strategy" from Kairui Song improves
   performance and reduces the failure rate of swap cluster allocation

 - "support large align and nid in Rust allocators" from Vitaly Wool
   permits Rust allocators to set NUMA node and large alignment when
   perforning slub and vmalloc reallocs

 - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend
   DAMOS_STAT's handling of the DAMON operations sets for virtual
   address spaces for ops-level DAMOS filters

 - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren
   Baghdasaryan reduces mmap_lock contention during reads of
   /proc/pid/maps

 - "mm/mincore: minor clean up for swap cache checking" from Kairui Song
   performs some cleanup in the swap code

 - "mm: vm_normal_page*() improvements" from David Hildenbrand provides
   code cleanup in the pagemap code

 - "add persistent huge zero folio support" from Pankaj Raghav provides
   a block layer speedup by optionalls making the
   huge_zero_pagepersistent, instead of releasing it when its refcount
   falls to zero

 - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to
   the recently added Kexec Handover feature

 - "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo
   Stoakes turns mm_struct.flags into a bitmap. To end the constant
   struggle with space shortage on 32-bit conflicting with 64-bit's
   needs

 - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap
   code

 - "selftests/mm: Fix false positives and skip unsupported tests" from
   Donet Tom fixes a few things in our selftests code

 - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised"
   from David Hildenbrand "allows individual processes to opt-out of
   THP=always into THP=madvise, without affecting other workloads on the
   system".

   It's a long story - the [1/N] changelog spells out the considerations

 - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on
   the memdesc project. Please see

      https://kernelnewbies.org/MatthewWilcox/Memdescs and
      https://blogs.oracle.com/linux/post/introducing-memdesc

 - "Tiny optimization for large read operations" from Chi Zhiling
   improves the efficiency of the pagecache read path

 - "Better split_huge_page_test result check" from Zi Yan improves our
   folio splitting selftest code

 - "test that rmap behaves as expected" from Wei Yang adds some rmap
   selftests

 - "remove write_cache_pages()" from Christoph Hellwig removes that
   function and converts its two remaining callers

 - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD
   selftests issues

 - "introduce kernel file mapped folios" from Boris Burkov introduces
   the concept of "kernel file pages". Using these permits btrfs to
   account its metadata pages to the root cgroup, rather than to the
   cgroups of random inappropriate tasks

 - "mm/pageblock: improve readability of some pageblock handling" from
   Wei Yang provides some readability improvements to the page allocator
   code

 - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON
   to understand arm32 highmem

 - "tools: testing: Use existing atomic.h for vma/maple tests" from
   Brendan Jackman performs some code cleanups and deduplication under
   tools/testing/

 - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes
   a couple of 32-bit issues in tools/testing/radix-tree.c

 - "kasan: unify kasan_enabled() and remove arch-specific
   implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific
   initialization code into a common arch-neutral implementation

 - "mm: remove zpool" from Johannes Weiner removes zspool - an
   indirection layer which now only redirects to a single thing
   (zsmalloc)

 - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a
   couple of cleanups in the fork code

 - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of
   adjustments at various nth_page() callsites, eventually permitting
   the removal of that undesirable helper function

 - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun
   creates a KASAN read-only mode for ARM, using that architecture's
   memory tagging feature. It is felt that a read-only mode KASAN is
   suitable for use in production systems rather than debug-only

 - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does
   some tidying in the hugetlb folio allocation code

 - "mm: establish const-correctness for pointer parameters" from Max
   Kellermann makes quite a number of the MM API functions more accurate
   about the constness of their arguments. This was getting in the way
   of subsystems (in this case CEPH) when they attempt to improving
   their own const/non-const accuracy

 - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of
   code sites which were confused over when to use free_pages() vs
   __free_pages()

 - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the
   mapletree code accessible to Rust. Required by nouveau and by its
   forthcoming successor: the new Rust Nova driver

 - "selftests/mm: split_huge_page_test: split_pte_mapped_thp
   improvements" from David Hildenbrand adds a fix and some cleanups to
   the thp selftesting code

 - "mm, swap: introduce swap table as swap cache (phase I)" from Chris
   Li and Kairui Song is the first step along the path to implementing
   "swap tables" - a new approach to swap allocation and state tracking
   which is expected to yield speed and space improvements. This
   patchset itself yields a 5-20% performance benefit in some situations

 - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc
   layer to clean up the ptdesc code a little

 - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some
   issues in our 5-level pagetable selftesting code

 - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan
   addresses a couple of minor issues in relatively new memory
   allocation profiling feature

 - "Small cleanups" from Matthew Wilcox has a few cleanups in
   preparation for more memdesc work

 - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from
   Quanmin Yan makes some changes to DAMON in furtherance of supporting
   arm highmem

 - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad
   Anjum adds that compiler check to selftests code and fixes the
   fallout, by removing dead code

 - "Improvements to Victim Process Thawing and OOM Reaper Traversal
   Order" from zhongjinji makes a number of improvements in the OOM
   killer: mainly thawing a more appropriate group of victim threads so
   they can release resources

 - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park
   is a bunch of small and unrelated fixups for DAMON

 - "mm/damon: define and use DAMON initialization check function" from
   SeongJae Park implement reliability and maintainability improvements
   to a recently-added bug fix

 - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from
   SeongJae Park provides additional transparency to userspace clients
   of the DAMON_STAT information

 - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes
   some constraints on khubepaged's collapsing of anon VMAs. It also
   increases the success rate of MADV_COLLAPSE against an anon vma

 - "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()"
   from Lorenzo Stoakes moves us further towards removal of
   file_operations.mmap(). This patchset concentrates upon clearing up
   the treatment of stacked filesystems

 - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau
   provides some fixes and improvements to mlock's tracking of large
   folios. /proc/meminfo's "Mlocked" field became more accurate

 - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from
   Donet Tom fixes several user-visible KSM stats inaccuracies across
   forks and adds selftest code to verify these counters

 - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses
   some potential but presently benign issues in KSM's mm_slot handling

* tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits)
  mm: swap: check for stable address space before operating on the VMA
  mm: convert folio_page() back to a macro
  mm/khugepaged: use start_addr/addr for improved readability
  hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list
  alloc_tag: fix boot failure due to NULL pointer dereference
  mm: silence data-race in update_hiwater_rss
  mm/memory-failure: don't select MEMORY_ISOLATION
  mm/khugepaged: remove definition of struct khugepaged_mm_slot
  mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
  hugetlb: increase number of reserving hugepages via cmdline
  selftests/mm: add fork inheritance test for ksm_merging_pages counter
  mm/ksm: fix incorrect KSM counter handling in mm_struct during fork
  drivers/base/node: fix double free in register_one_node()
  mm: remove PMD alignment constraint in execmem_vmalloc()
  mm/memory_hotplug: fix typo 'esecially' -> 'especially'
  mm/rmap: improve mlock tracking for large folios
  mm/filemap: map entire large folio faultaround
  mm/fault: try to map the entire file folio in finish_fault()
  mm/rmap: mlock large folios in try_to_unmap_one()
  mm/rmap: fix a mlock race condition in folio_referenced_one()
  ...

rust: add support for NUMA ids in allocations

2025-09-13T23:54:46+00:00

Add a new type to support specifying NUMA identifiers in Rust allocators
and extend the allocators to have NUMA id as a parameter.  Thus, modify
ReallocFunc to use the new extended realloc primitives from the C side of
the kernel (i.e.  k[v]realloc_node_align/vrealloc_node_align) and add the
new function alloc_node to the Allocator trait while keeping the existing
one (alloc) for backward compatibility.

This will allow to specify node to use for allocation of e.  g.  {KV}Box,
as well as for future NUMA aware users of the API.

[ojeda@kernel.org: fix missing import needed for `rusttest`]
  Link: https://lkml.kernel.org/r/20250816210214.2729269-1-ojeda@kernel.org
Link: https://lkml.kernel.org/r/20250806125522.1726992-1-vitaly.wool@konsulko.se
Signed-off-by: Vitaly Wool 
Signed-off-by: Miguel Ojeda 
Acked-by: Danilo Krummrich 
Acked-by: Alice Ryhl 
Cc: Herbert Xu 
Cc: Jann Horn 
Cc: Kent Overstreet 
Cc: Liam Howlett 
Cc: Lorenzo Stoakes 
Cc: Uladzislau Rezki (Sony) 
Cc: Vlastimil Babka 
Cc: Miguel Ojeda 
Signed-off-by: Andrew Morton

rust: alloc: remove `allocator_test`

2025-08-24T13:30:40+00:00

Given we do not have tests that rely on it anymore, remove
`allocator_test`, which simplifies the complexity of the build.

In particular, it avoids potential issues with `rusttest`, such as the
one fixed at [1], where a public function was added to `Kmalloc` and
used elsewhere, but it was not added to `Cmalloc`; or trivial issues
like a missing import [2] due to not many people testing that target.

The only downside is that we cannot use it in the `macros`' crate
examples anymore, but we did not feel a need for that so far, and anyway
we could support that by running those within the kernel too, which we
may do regardless.

Link: https://lore.kernel.org/rust-for-linux/20250816204215.2719559-1-ojeda@kernel.org/ [1]
Link: https://lore.kernel.org/rust-for-linux/20250816210214.2729269-1-ojeda@kernel.org/ [2]
Signed-off-by: Miguel Ojeda 
Link: https://lore.kernel.org/r/20250816211900.2731720-1-ojeda@kernel.org
Signed-off-by: Danilo Krummrich

rust: kernel: remove support for unused host `#[test]`s

2025-08-24T13:29:51+00:00

Since commit 028df914e546 ("rust: str: convert `rusttest` tests into
KUnit"), we do not have anymore host `#[test]`s that run in the host.

Moreover, we do not plan to add any new ones -- tests should generally
run within KUnit, since there they are built the same way the kernel
does. While we may want to have some way to define tests that can also
be run outside the kernel, we still want to test within the kernel too
[1], and thus would likely use a custom syntax anyway to define them.

Thus simplify the `rusttest` target by removing support for host
`#[test]`s for the `kernel` crate.

This still maintains the support for the `macros` crate, even though we
do not have any such tests there.

Link: https://lore.kernel.org/rust-for-linux/CABVgOS=AKHSfifp0S68K3jgNZAkALBr=7iFb=niryG5WDxjSrg@mail.gmail.com/ [1]
Signed-off-by: Miguel Ojeda 
Reviewed-by: Danilo Krummrich 
Reviewed-by: David Gow 
Link: https://lore.kernel.org/r/20250726180750.2735836-1-ojeda@kernel.org
Signed-off-by: Danilo Krummrich

rust: alloc: specify the minimum alignment of each allocator

2025-08-15T18:55:16+00:00

The kernel's allocators sometimes provide a higher alignment than the
end-user requested, so add a new constant on the Allocator trait to let
the allocator specify what its minimum guaranteed alignment is.

This allows the ForeignOwnable trait to provide a more accurate value of
FOREIGN_ALIGN when using a pointer type such as Box, which will be
useful with certain collections such as XArray that store its own data
in the low bits of pointers.

Reviewed-by: Benno Lossin 
Signed-off-by: Alice Ryhl 
Acked-by: Liam R. Howlett 
Reviewed-by: Andreas Hindborg 
Link: https://lore.kernel.org/r/20250811-align-min-allocator-v2-1-3386cc94f4fc@google.com
[ Add helper for ARCH_KMALLOC_MINALIGN; remove cast to usize. - Danilo ]
Signed-off-by: Danilo Krummrich

rust: alloc: add missing Markdown code spans

2025-05-25T20:58:35+00:00

Add missing Markdown code spans.

This was found using the Clippy `doc_markdown` lint, which we may want
to enable.

Fixes: b6a006e21b82 ("rust: alloc: introduce allocation flags")
Reviewed-by: Benno Lossin 
Acked-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20250324210359.1199574-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda

rust: use derive(CoercePointee) on rustc >= 1.84.0

2025-01-13T22:45:30+00:00

The `kernel` crate relies on both `coerce_unsized` and `dispatch_from_dyn`
unstable features.

Alice Ryhl has proposed [1] the introduction of the unstable macro
`SmartPointer` to reduce such dependence, along with a RFC patch [2].
Since Rust 1.81.0 this macro, later renamed to `CoercePointee` in
Rust 1.84.0 [3], has been fully implemented with the naming discussion
resolved.

This feature is now on track to stabilization in the language.
In order to do so, we shall start using this macro in the `kernel` crate
to prove the functionality and utility of the macro as the justification
of its stabilization.

This patch makes this switch in such a way that the crate remains
backward compatible with older Rust compiler versions,
via the new Kconfig option `RUSTC_HAS_COERCE_POINTEE`.

A minimal demonstration example is added to the
`samples/rust/rust_print_main.rs` module.

Link: https://rust-lang.github.io/rfcs/3621-derive-smart-pointer.html [1]
Link: https://lore.kernel.org/all/20240823-derive-smart-pointer-v1-1-53769cd37239@google.com/ [2]
Link: https://github.com/rust-lang/rust/pull/131284 [3]
Signed-off-by: Xiangfei Ding
Reviewed-by: Fiona Behrens
Reviewed-by: Alice Ryhl
Link: https://lore.kernel.org/r/20241203205050.679106-2-dingxiangfei2009@gmail.com
[ Fixed version to 1.84. Renamed option to `RUSTC_HAS_COERCE_POINTEE`
to match `CC_HAS_*` ones. Moved up new config option, closer to the
`CC_HAS_*` ones. Simplified Kconfig line. Fixed typos and slightly
reworded example and commit. Added Link to PR. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: update module comment of alloc.rs

2024-10-15T21:10:32+00:00

Before we remove Rust's alloc crate, rewrite the module comment in
alloc.rs to avoid a rustdoc warning.

Besides that, the module comment in alloc.rs isn't correct anymore,
we're no longer extending Rust's alloc crate.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-28-dakr@kernel.org
Signed-off-by: Miguel Ojeda

rust: alloc: implement `Cmalloc` in module allocator_test

2024-10-15T21:10:32+00:00

So far the kernel's `Box` and `Vec` types can't be used by userspace
test cases, since all users of those types (e.g. `CString`) use kernel
allocators for instantiation.

In order to allow userspace test cases to make use of such types as
well, implement the `Cmalloc` allocator within the allocator_test module
and type alias all kernel allocators to `Cmalloc`. The `Cmalloc`
allocator uses libc's `realloc()` function as allocator backend.

Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-26-dakr@kernel.org
[ Removed the temporary `allow(dead_code)` as discussed in the list and
  fixed typo, added backticks. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: implement `contains` for `Flags`

2024-10-15T21:10:32+00:00

Provide a simple helper function to check whether given flags do
contain one or multiple other flags.

This is used by a subsequent patch implementing the Cmalloc `Allocator`
to check for __GFP_ZERO.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-25-dakr@kernel.org
Signed-off-by: Miguel Ojeda