linux/rust/kernel/mm, branch v6.18

rust: mm: update ARef and AlwaysRefCounted imports from sync::aref

2025-09-13T23:55:15Z

Update call sites in the mm subsystem to import `ARef` and `AlwaysRefCounted` from `sync::aref` instead of `types`. This aligns with the ongoing effort to move `ARef` and `AlwaysRefCounted` to sync. Link: https://lkml.kernel.org/r/20250716091158.812860-1-shankari.ak0208@gmail.com Signed-off-by: Shankari Anand Suggested-by: Benno Lossin Link: https://github.com/Rust-for-Linux/linux/issues/1173 Acked-by: Alice Ryhl Cc: Alex Gaynor Cc: Andreas Hindborg Cc: Björn Roy Baron Cc: Boqun Feng Cc: Danilo Krummrich Cc: Gary Guo Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Miguel Ojeda Cc: Trevor Gross Signed-off-by: Andrew Morton

rust: mm: mark VmaNew as transparent

2025-08-28T05:45:41Z

Unsafe code in VmaNew's methods assumes that the type has the same layout as the inner `bindings::vm_area_struct`. This is not guaranteed by the default struct representation in Rust, but requires specifying the `transparent` representation. Link: https://lkml.kernel.org/r/20250812132712.61007-1-baptiste.lepers@gmail.com Fixes: dcb81aeab406 ("mm: rust: add VmaNew for f_ops->mmap()") Signed-off-by: Baptiste Lepers Reviewed-by: Alice Ryhl Cc: Alex Gaynor Cc: Andreas Hindborg Cc: Björn Roy Baron Cc: Boqun Feng Cc: Danilo Krummrich Cc: Gary Guo Cc: Jann Horn Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Miguel Ojeda Cc: Trevor Gross Cc: Signed-off-by: Andrew Morton

rust: enable `clippy::as_underscore` lint

2025-06-22T21:09:17Z

In Rust 1.63.0, Clippy introduced the `as_underscore` lint [1]: > The conversion might include lossy conversion or a dangerous cast that > might go undetected due to the type being inferred. > > The lint is allowed by default as using `_` is less wordy than always > specifying the type. Always specifying the type is especially helpful in function call contexts where the inferred type may change at a distance. Specifying the type also allows Clippy to spot more cases of `useless_conversion`. The primary downside is the need to specify the type in trivial getters. There are 4 such functions: 3 have become slightly less ergonomic, 1 was revealed to be a `useless_conversion`. While this doesn't eliminate unchecked `as` conversions, it makes such conversions easier to scrutinize. It also has the slight benefit of removing a degree of freedom on which to bikeshed. Thus apply the changes and enable the lint -- no functional change intended. Link: https://rust-lang.github.io/rust-clippy/master/index.html#as_underscore [1] Reviewed-by: Benno Lossin Reviewed-by: Boqun Feng Signed-off-by: Tamir Duberstein Acked-by: Greg Kroah-Hartman Acked-by: Danilo Krummrich Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-4-f43b024581e8@gmail.com [ Changed `isize` to `c_long`. - Miguel ] Signed-off-by: Miguel Ojeda

mm: rust: make CONFIG_MMU ifdefs more narrow

2025-06-01T05:46:12Z

Currently the entire kernel::mm module is ifdef'd out when CONFIG_MMU=n. However, there are some downstream users of the module in rust/kernel/task.rs and rust/kernel/miscdevice.rs. Thus, update the cfgs so that only MmWithUserAsync is removed with CONFIG_MMU=n. The code is moved into a new file, since the #[cfg()] annotation otherwise has to be duplicated several times. Link: https://lkml.kernel.org/r/20250516193219.2987032-1-aliceryhl@google.com Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202505071753.kldNHYVQ-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202505072116.eSYC8igT-lkp@intel.com/ Fixes: 5bb9ed6cdfeb ("mm: rust: add abstraction for struct mm_struct") Signed-off-by: Alice Ryhl Reviewed-by: Boqun Feng Cc: Boqun Feng Cc: Liam Howlett Cc: Lorenzo Stoakes Signed-off-by: Andrew Morton

mm: rust: add VmaNew for f_ops->mmap()

2025-05-12T00:48:25Z

This type will be used when setting up a new vma in an f_ops->mmap() hook. Using a separate type from VmaRef allows us to have a separate set of operations that you are only able to use during the mmap() hook. For example, the VM_MIXEDMAP flag must not be changed after the initial setup that happens during the f_ops->mmap() hook. To avoid setting invalid flag values, the methods for clearing VM_MAYWRITE and similar involve a check of VM_WRITE, and return an error if VM_WRITE is set. Trying to use `try_clear_maywrite` without checking the return value results in a compilation error because the `Result` type is marked #[must_use]. For now, there's only a method for VM_MIXEDMAP and not VM_PFNMAP. When we add a VM_PFNMAP method, we will need some way to prevent you from setting both VM_MIXEDMAP and VM_PFNMAP on the same vma. Link: https://lkml.kernel.org/r/20250408-vma-v16-6-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Jann Horn Reviewed-by: Andreas Hindborg Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Gary Guo Cc: Greg Kroah-Hartman Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: rust: add vm_insert_page

2025-05-12T00:48:24Z

The vm_insert_page method is only usable on vmas with the VM_MIXEDMAP flag, so we introduce a new type to keep track of such vmas. The approach used in this patch assumes that we will not need to encode many flag combinations in the type. I don't think we need to encode more than VM_MIXEDMAP and VM_PFNMAP as things are now. However, if that becomes necessary, using generic parameters in a single type would scale better as the number of flags increases. Link: https://lkml.kernel.org/r/20250408-vma-v16-3-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: Jann Horn Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: rust: add vm_area_struct methods that require read access

2025-05-12T00:48:24Z

This adds a type called VmaRef which is used when referencing a vma that you have read access to. Here, read access means that you hold either the mmap read lock or the vma read lock (or stronger). Additionally, a vma_lookup method is added to the mmap read guard, which enables you to obtain a &VmaRef in safe Rust code. This patch only provides a way to lock the mmap read lock, but a follow-up patch also provides a way to just lock the vma read lock. Link: https://lkml.kernel.org/r/20250408-vma-v16-2-d8b446e885d9@google.com Signed-off-by: Alice Ryhl Acked-by: Lorenzo Stoakes Acked-by: Liam R. Howlett Reviewed-by: Jann Horn Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo Cc: Alex Gaynor Cc: Arnd Bergmann Cc: Balbir Singh Cc: Benno Lossin Cc: Björn Roy Baron Cc: Boqun Feng Cc: Greg Kroah-Hartman Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miguel Ojeda Cc: Suren Baghdasaryan Cc: Trevor Gross Cc: Vlastimil Babka Signed-off-by: Andrew Morton