23 files changed, 754 insertions, 177 deletions

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
new file mode 100644
index 000000000000..531b5e471cb1
--- /dev/null
+++ b/rust/kernel/alloc.rs
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to the [`alloc`] crate.
+
+#[cfg(not(test))]
+#[cfg(not(testlib))]
+mod allocator;
+pub mod box_ext;
+pub mod vec_ext;
+
+/// Indicates an allocation error.
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+pub struct AllocError;
+
+/// Flags to be used when allocating memory.
+///
+/// They can be combined with the operators `|`, `&`, and `!`.
+///
+/// Values can be used from the [`flags`] module.
+#[derive(Clone, Copy)]
+pub struct Flags(u32);
+
+impl core::ops::BitOr for Flags {
+    type Output = Self;
+    fn bitor(self, rhs: Self) -> Self::Output {
+        Self(self.0 | rhs.0)
+    }
+}
+
+impl core::ops::BitAnd for Flags {
+    type Output = Self;
+    fn bitand(self, rhs: Self) -> Self::Output {
+        Self(self.0 & rhs.0)
+    }
+}
+
+impl core::ops::Not for Flags {
+    type Output = Self;
+    fn not(self) -> Self::Output {
+        Self(!self.0)
+    }
+}
+
+/// Allocation flags.
+///
+/// These are meant to be used in functions that can allocate memory.
+pub mod flags {
+    use super::Flags;
+
+    /// Zeroes out the allocated memory.
+    ///
+    /// This is normally or'd with other flags.
+    pub const __GFP_ZERO: Flags = Flags(bindings::__GFP_ZERO);
+
+    /// Users can not sleep and need the allocation to succeed.
+    ///
+    /// A lower watermark is applied to allow access to "atomic reserves". The current
+    /// implementation doesn't support NMI and few other strict non-preemptive contexts (e.g.
+    /// raw_spin_lock). The same applies to [`GFP_NOWAIT`].
+    pub const GFP_ATOMIC: Flags = Flags(bindings::GFP_ATOMIC);
+
+    /// Typical for kernel-internal allocations. The caller requires ZONE_NORMAL or a lower zone
+    /// for direct access but can direct reclaim.
+    pub const GFP_KERNEL: Flags = Flags(bindings::GFP_KERNEL);
+
+    /// The same as [`GFP_KERNEL`], except the allocation is accounted to kmemcg.
+    pub const GFP_KERNEL_ACCOUNT: Flags = Flags(bindings::GFP_KERNEL_ACCOUNT);
+
+    /// Ror kernel allocations that should not stall for direct reclaim, start physical IO or
+    /// use any filesystem callback.  It is very likely to fail to allocate memory, even for very
+    /// small allocations.
+    pub const GFP_NOWAIT: Flags = Flags(bindings::GFP_NOWAIT);
+}
diff --git a/rust/kernel/allocator.rs b/rust/kernel/alloc/allocator.rs
index 01ad139e19bc..229642960cd1 100644
--- a/rust/kernel/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -2,11 +2,10 @@
 
 //! Allocator support.
 
+use super::{flags::*, Flags};
 use core::alloc::{GlobalAlloc, Layout};
 use core::ptr;
 
-use crate::bindings;
-
 struct KernelAllocator;
 
 /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.
@@ -15,7 +14,7 @@ struct KernelAllocator;
 ///
 /// - `ptr` can be either null or a pointer which has been allocated by this allocator.
 /// - `new_layout` must have a non-zero size.
-unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 {
+pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {
     // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.
     let layout = new_layout.pad_to_align();
 
@@ -36,14 +35,14 @@ unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gf
     //   function safety requirement.
     // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero
     //   according to the function safety requirement) or a result from `next_power_of_two()`.
-    unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 }
+    unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
 }
 
 unsafe impl GlobalAlloc for KernelAllocator {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
         // requirement.
-        unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) }
+        unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL) }
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
@@ -64,19 +63,13 @@ unsafe impl GlobalAlloc for KernelAllocator {
         //   requirement.
         // - the size of `layout` is not zero because `new_size` is not zero by the function safety
         //   requirement.
-        unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) }
+        unsafe { krealloc_aligned(ptr, layout, GFP_KERNEL) }
     }
 
     unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
         // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
         // requirement.
-        unsafe {
-            krealloc_aligned(
-                ptr::null_mut(),
-                layout,
-                bindings::GFP_KERNEL | bindings::__GFP_ZERO,
-            )
-        }
+        unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL | __GFP_ZERO) }
     }
 }
 
diff --git a/rust/kernel/alloc/box_ext.rs b/rust/kernel/alloc/box_ext.rs
new file mode 100644
index 000000000000..829cb1c1cf9e
--- /dev/null
+++ b/rust/kernel/alloc/box_ext.rs
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to [`Box`] for fallible allocations.
+
+use super::{AllocError, Flags};
+use alloc::boxed::Box;
+use core::mem::MaybeUninit;
+
+/// Extensions to [`Box`].
+pub trait BoxExt<T>: Sized {
+    /// Allocates a new box.
+    ///
+    /// The allocation may fail, in which case an error is returned.
+    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
+
+    /// Allocates a new uninitialised box.
+    ///
+    /// The allocation may fail, in which case an error is returned.
+    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
+}
+
+impl<T> BoxExt<T> for Box<T> {
+    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
+        let b = <Self as BoxExt<_>>::new_uninit(flags)?;
+        Ok(Box::write(b, x))
+    }
+
+    #[cfg(any(test, testlib))]
+    fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
+        Ok(Box::new_uninit())
+    }
+
+    #[cfg(not(any(test, testlib)))]
+    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
+        let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 {
+            core::ptr::NonNull::<_>::dangling().as_ptr()
+        } else {
+            let layout = core::alloc::Layout::new::<MaybeUninit<T>>();
+
+            // SAFETY: Memory is being allocated (first arg is null). The only other source of
+            // safety issues is sleeping on atomic context, which is addressed by klint. Lastly,
+            // the type is not a SZT (checked above).
+            let ptr =
+                unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) };
+            if ptr.is_null() {
+                return Err(AllocError);
+            }
+
+            ptr.cast::<MaybeUninit<T>>()
+        };
+
+        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
+        // zero-sized types, we use `NonNull::dangling`.
+        Ok(unsafe { Box::from_raw(ptr) })
+    }
+}
diff --git a/rust/kernel/alloc/vec_ext.rs b/rust/kernel/alloc/vec_ext.rs
new file mode 100644
index 000000000000..e9a81052728a
--- /dev/null
+++ b/rust/kernel/alloc/vec_ext.rs
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Extensions to [`Vec`] for fallible allocations.
+
+use super::{AllocError, Flags};
+use alloc::vec::Vec;
+use core::ptr;
+
+/// Extensions to [`Vec`].
+pub trait VecExt<T>: Sized {
+    /// Creates a new [`Vec`] instance with at least the given capacity.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let v = Vec::<u32>::with_capacity(20, GFP_KERNEL)?;
+    ///
+    /// assert!(v.capacity() >= 20);
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError>;
+
+    /// Appends an element to the back of the [`Vec`] instance.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = Vec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1]);
+    ///
+    /// v.push(2, GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 2]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError>;
+
+    /// Pushes clones of the elements of slice into the [`Vec`] instance.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = Vec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    ///
+    /// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 20, 30, 40]);
+    ///
+    /// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;
+    /// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
+    where
+        T: Clone;
+
+    /// Ensures that the capacity exceeds the length by at least `additional` elements.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let mut v = Vec::new();
+    /// v.push(1, GFP_KERNEL)?;
+    ///
+    /// v.reserve(10, GFP_KERNEL)?;
+    /// let cap = v.capacity();
+    /// assert!(cap >= 10);
+    ///
+    /// v.reserve(10, GFP_KERNEL)?;
+    /// let new_cap = v.capacity();
+    /// assert_eq!(new_cap, cap);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>;
+}
+
+impl<T> VecExt<T> for Vec<T> {
+    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
+        let mut v = Vec::new();
+        <Self as VecExt<_>>::reserve(&mut v, capacity, flags)?;
+        Ok(v)
+    }
+
+    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
+        <Self as VecExt<_>>::reserve(self, 1, flags)?;
+        let s = self.spare_capacity_mut();
+        s[0].write(v);
+
+        // SAFETY: We just initialised the first spare entry, so it is safe to increase the length
+        // by 1. We also know that the new length is <= capacity because of the previous call to
+        // `reserve` above.
+        unsafe { self.set_len(self.len() + 1) };
+        Ok(())
+    }
+
+    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
+    where
+        T: Clone,
+    {
+        <Self as VecExt<_>>::reserve(self, other.len(), flags)?;
+        for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {
+            slot.write(item.clone());
+        }
+
+        // SAFETY: We just initialised the `other.len()` spare entries, so it is safe to increase
+        // the length by the same amount. We also know that the new length is <= capacity because
+        // of the previous call to `reserve` above.
+        unsafe { self.set_len(self.len() + other.len()) };
+        Ok(())
+    }
+
+    #[cfg(any(test, testlib))]
+    fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError> {
+        Vec::reserve(self, additional);
+        Ok(())
+    }
+
+    #[cfg(not(any(test, testlib)))]
+    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
+        let len = self.len();
+        let cap = self.capacity();
+
+        if cap - len >= additional {
+            return Ok(());
+        }
+
+        if core::mem::size_of::<T>() == 0 {
+            // The capacity is already `usize::MAX` for SZTs, we can't go higher.
+            return Err(AllocError);
+        }
+
+        // We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size
+        // is greater than `isize::MAX`. So the multiplication by two won't overflow.
+        let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
+        let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;
+
+        let (old_ptr, len, cap) = destructure(self);
+
+        // We need to make sure that `ptr` is either NULL or comes from a previous call to
+        // `krealloc_aligned`. A `Vec<T>`'s `ptr` value is not guaranteed to be NULL and might be
+        // dangling after being created with `Vec::new`. Instead, we can rely on `Vec<T>`'s capacity
+        // to be zero if no memory has been allocated yet.
+        let ptr = if cap == 0 { ptr::null_mut() } else { old_ptr };
+
+        // SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to
+        // `krealloc_aligned`. We also verified that the type is not a ZST.
+        let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags) };
+        if new_ptr.is_null() {
+            // SAFETY: We are just rebuilding the existing `Vec` with no changes.
+            unsafe { rebuild(self, old_ptr, len, cap) };
+            Err(AllocError)
+        } else {
+            // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap
+            // is greater than `cap`, so it continues to be >= `len`.
+            unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };
+            Ok(())
+        }
+    }
+}
+
+#[cfg(not(any(test, testlib)))]
+fn destructure<T>(v: &mut Vec<T>) -> (*mut T, usize, usize) {
+    let mut tmp = Vec::new();
+    core::mem::swap(&mut tmp, v);
+    let mut tmp = core::mem::ManuallyDrop::new(tmp);
+    let len = tmp.len();
+    let cap = tmp.capacity();
+    (tmp.as_mut_ptr(), len, cap)
+}
+
+/// Rebuilds a `Vec` from a pointer, length, and capacity.
+///
+/// # Safety
+///
+/// The same as [`Vec::from_raw_parts`].
+#[cfg(not(any(test, testlib)))]
+unsafe fn rebuild<T>(v: &mut Vec<T>, ptr: *mut T, len: usize, cap: usize) {
+    // SAFETY: The safety requirements from this function satisfy those of `from_raw_parts`.
+    let mut tmp = unsafe { Vec::from_raw_parts(ptr, len, cap) };
+    core::mem::swap(&mut tmp, v);
+}
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 4786d3ee1e92..55280ae9fe40 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -4,14 +4,10 @@
 //!
 //! C header: [`include/uapi/asm-generic/errno-base.h`](srctree/include/uapi/asm-generic/errno-base.h)
 
-use crate::str::CStr;
+use crate::{alloc::AllocError, str::CStr};
 
-use alloc::{
-    alloc::{AllocError, LayoutError},
-    collections::TryReserveError,
-};
+use alloc::alloc::LayoutError;
 
-use core::convert::From;
 use core::fmt;
 use core::num::TryFromIntError;
 use core::str::Utf8Error;
@@ -192,12 +188,6 @@ impl From<Utf8Error> for Error {
     }
 }
 
-impl From<TryReserveError> for Error {
-    fn from(_: TryReserveError) -> Error {
-        code::ENOMEM
-    }
-}
-
 impl From<LayoutError> for Error {
     fn from(_: LayoutError) -> Error {
         code::ENOMEM
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index 424257284d16..68605b633e73 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -68,7 +68,7 @@
 //! #     a <- new_mutex!(42, "Foo::a"),
 //! #     b: 24,
 //! # });
-//! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo);
+//! let foo: Result<Pin<Box<Foo>>> = Box::pin_init(foo, GFP_KERNEL);
 //! ```
 //!
 //! For more information see the [`pin_init!`] macro.
@@ -80,14 +80,15 @@
 //!
 //! ```rust
 //! # use kernel::sync::{new_mutex, Arc, Mutex};
-//! let mtx: Result<Arc<Mutex<usize>>> = Arc::pin_init(new_mutex!(42, "example::mtx"));
+//! let mtx: Result<Arc<Mutex<usize>>> =
+//!     Arc::pin_init(new_mutex!(42, "example::mtx"), GFP_KERNEL);
 //! ```
 //!
 //! To declare an init macro/function you just return an [`impl PinInit<T, E>`]:
 //!
 //! ```rust
 //! # #![allow(clippy::disallowed_names)]
-//! # use kernel::{sync::Mutex, prelude::*, new_mutex, init::PinInit, try_pin_init};
+//! # use kernel::{sync::Mutex, new_mutex, init::PinInit, try_pin_init};
 //! #[pin_data]
 //! struct DriverData {
 //!     #[pin]
@@ -99,7 +100,7 @@
 //!     fn new() -> impl PinInit<Self, Error> {
 //!         try_pin_init!(Self {
 //!             status <- new_mutex!(0, "DriverData::status"),
-//!             buffer: Box::init(kernel::init::zeroed())?,
+//!             buffer: Box::init(kernel::init::zeroed(), GFP_KERNEL)?,
 //!         })
 //!     }
 //! }
@@ -121,7 +122,7 @@
 //!
 //! ```rust
 //! # #![allow(unreachable_pub, clippy::disallowed_names)]
-//! use kernel::{prelude::*, init, types::Opaque};
+//! use kernel::{init, types::Opaque};
 //! use core::{ptr::addr_of_mut, marker::PhantomPinned, pin::Pin};
 //! # mod bindings {
 //! #     #![allow(non_camel_case_types)]
@@ -210,13 +211,13 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
+    alloc::{box_ext::BoxExt, AllocError, Flags},
     error::{self, Error},
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
 };
 use alloc::boxed::Box;
 use core::{
-    alloc::AllocError,
     cell::UnsafeCell,
     convert::Infallible,
     marker::PhantomData,
@@ -305,9 +306,9 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Result<Pin<&mut Foo>, AllocError> = pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::try_new(Bar {
+///     b: Box::new(Bar {
 ///         x: 64,
-///     })?,
+///     }, GFP_KERNEL)?,
 /// }));
 /// let foo = foo.unwrap();
 /// pr_info!("a: {}", &*foo.a.lock());
@@ -331,9 +332,9 @@ macro_rules! stack_pin_init {
 ///
 /// stack_try_pin_init!(let foo: Pin<&mut Foo> =? pin_init!(Foo {
 ///     a <- new_mutex!(42),
-///     b: Box::try_new(Bar {
+///     b: Box::new(Bar {
 ///         x: 64,
-///     })?,
+///     }, GFP_KERNEL)?,
 /// }));
 /// pr_info!("a: {}", &*foo.a.lock());
 /// # Ok::<_, AllocError>(())
@@ -390,7 +391,7 @@ macro_rules! stack_try_pin_init {
 ///     },
 /// });
 /// # initializer }
-/// # Box::pin_init(demo()).unwrap();
+/// # Box::pin_init(demo(), GFP_KERNEL).unwrap();
 /// ```
 ///
 /// Arbitrary Rust expressions can be used to set the value of a variable.
@@ -412,7 +413,7 @@ macro_rules! stack_try_pin_init {
 ///
 /// ```rust
 /// # #![allow(clippy::disallowed_names)]
-/// # use kernel::{init, pin_init, prelude::*, init::*};
+/// # use kernel::{init, pin_init, init::*};
 /// # use core::pin::Pin;
 /// # #[pin_data]
 /// # struct Foo {
@@ -460,7 +461,7 @@ macro_rules! stack_try_pin_init {
 /// #         })
 /// #     }
 /// # }
-/// let foo = Box::pin_init(Foo::new());
+/// let foo = Box::pin_init(Foo::new(), GFP_KERNEL);
 /// ```
 ///
 /// They can also easily embed it into their own `struct`s:
@@ -600,7 +601,7 @@ macro_rules! pin_init {
 /// impl BigBuf {
 ///     fn new() -> impl PinInit<Self, Error> {
 ///         try_pin_init!(Self {
-///             big: Box::init(init::zeroed())?,
+///             big: Box::init(init::zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///             ptr: core::ptr::null_mut(),
 ///         }? Error)
@@ -701,7 +702,7 @@ macro_rules! init {
 /// impl BigBuf {
 ///     fn new() -> impl Init<Self, Error> {
 ///         try_init!(Self {
-///             big: Box::init(zeroed())?,
+///             big: Box::init(zeroed(), GFP_KERNEL)?,
 ///             small: [0; 1024 * 1024],
 ///         }? Error)
 ///     }
@@ -1013,7 +1014,7 @@ pub fn uninit<T, E>() -> impl Init<MaybeUninit<T>, E> {
 ///
 /// ```rust
 /// use kernel::{error::Error, init::init_array_from_fn};
-/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i)).unwrap();
+/// let array: Box<[usize; 1_000]> = Box::init::<Error>(init_array_from_fn(|i| i), GFP_KERNEL).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn init_array_from_fn<I, const N: usize, T, E>(
@@ -1057,7 +1058,7 @@ where
 /// ```rust
 /// use kernel::{sync::{Arc, Mutex}, init::pin_init_array_from_fn, new_mutex};
 /// let array: Arc<[Mutex<usize>; 1_000]> =
-///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i))).unwrap();
+///     Arc::pin_init(pin_init_array_from_fn(|i| new_mutex!(i)), GFP_KERNEL).unwrap();
 /// assert_eq!(array.len(), 1_000);
 /// ```
 pub fn pin_init_array_from_fn<I, const N: usize, T, E>(
@@ -1115,7 +1116,7 @@ pub trait InPlaceInit<T>: Sized {
     /// type.
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>;
 
@@ -1123,7 +1124,7 @@ pub trait InPlaceInit<T>: Sized {
     /// type.
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
-    fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Pin<Self>>
+    fn pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> error::Result<Pin<Self>>
     where
         Error: From<E>,
     {
@@ -1131,16 +1132,16 @@ pub trait InPlaceInit<T>: Sized {
         let init = unsafe {
             pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
         };
-        Self::try_pin_init(init)
+        Self::try_pin_init(init, flags)
     }
 
     /// Use the given initializer to in-place initialize a `T`.
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>;
 
     /// Use the given initializer to in-place initialize a `T`.
-    fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
+    fn init<E>(init: impl Init<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
@@ -1148,17 +1149,17 @@ pub trait InPlaceInit<T>: Sized {
         let init = unsafe {
             init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| Error::from(e)))
         };
-        Self::try_init(init)
+        Self::try_init(init, flags)
     }
 }
 
 impl<T> InPlaceInit<T> for Box<T> {
     #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = Box::try_new_uninit()?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1168,11 +1169,11 @@ impl<T> InPlaceInit<T> for Box<T> {
     }
 
     #[inline]
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = Box::try_new_uninit()?;
+        let mut this = <Box<_> as BoxExt<_>>::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
@@ -1184,11 +1185,11 @@ impl<T> InPlaceInit<T> for Box<T> {
 
 impl<T> InPlaceInit<T> for UniqueArc<T> {
     #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
+    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1198,11 +1199,11 @@ impl<T> InPlaceInit<T> for UniqueArc<T> {
     }
 
     #[inline]
-    fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
+    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(flags)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.
@@ -1292,8 +1293,15 @@ impl_zeroable! {
     i8, i16, i32, i64, i128, isize,
     f32, f64,
 
-    // SAFETY: These are ZSTs, there is nothing to zero.
-    {<T: ?Sized>} PhantomData<T>, core::marker::PhantomPinned, Infallible, (),
+    // Note: do not add uninhabited types (such as `!` or `core::convert::Infallible`) to this list;
+    // creating an instance of an uninhabited type is immediate undefined behavior. For more on
+    // uninhabited/empty types, consult The Rustonomicon:
+    // <https://doc.rust-lang.org/stable/nomicon/exotic-sizes.html#empty-types>. The Rust Reference
+    // also has information on undefined behavior:
+    // <https://doc.rust-lang.org/stable/reference/behavior-considered-undefined.html>.
+    //
+    // SAFETY: These are inhabited ZSTs; there is nothing to zero and a valid value exists.
+    {<T: ?Sized>} PhantomData<T>, core::marker::PhantomPinned, (),
 
     // SAFETY: Type is allowed to take any value, including all zeros.
     {<T>} MaybeUninit<T>,
diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
index cb6e61b6c50b..02ecedc4ae7a 100644
--- a/rust/kernel/init/macros.rs
+++ b/rust/kernel/init/macros.rs
@@ -250,7 +250,7 @@
 //!                     // error type is `Infallible`) we will need to drop this field if there
 //!                     // is an error later. This `DropGuard` will drop the field when it gets
 //!                     // dropped and has not yet been forgotten.
-//!                     let t = unsafe {
+//!                     let __t_guard = unsafe {
 //!                         ::pinned_init::__internal::DropGuard::new(::core::addr_of_mut!((*slot).t))
 //!                     };
 //!                     // Expansion of `x: 0,`:
@@ -261,14 +261,14 @@
 //!                         unsafe { ::core::ptr::write(::core::addr_of_mut!((*slot).x), x) };
 //!                     }
 //!                     // We again create a `DropGuard`.
-//!                     let x = unsafe {
+//!                     let __x_guard = unsafe {
 //!                         ::kernel::init::__internal::DropGuard::new(::core::addr_of_mut!((*slot).x))
 //!                     };
 //!                     // Since initialization has successfully completed, we can now forget
 //!                     // the guards. This is not `mem::forget`, since we only have
 //!                     // `&DropGuard`.
-//!                     ::core::mem::forget(x);
-//!                     ::core::mem::forget(t);
+//!                     ::core::mem::forget(__x_guard);
+//!                     ::core::mem::forget(__t_guard);
 //!                     // Here we use the type checker to ensure that every field has been
 //!                     // initialized exactly once, since this is `if false` it will never get
 //!                     // executed, but still type-checked.
@@ -461,16 +461,16 @@
 //!             {
 //!                 unsafe { ::core::ptr::write(::core::addr_of_mut!((*slot).a), a) };
 //!             }
-//!             let a = unsafe {
+//!             let __a_guard = unsafe {
 //!                 ::kernel::init::__internal::DropGuard::new(::core::addr_of_mut!((*slot).a))
 //!             };
 //!             let init = Bar::new(36);
 //!             unsafe { data.b(::core::addr_of_mut!((*slot).b), b)? };
-//!             let b = unsafe {
+//!             let __b_guard = unsafe {
 //!                 ::kernel::init::__internal::DropGuard::new(::core::addr_of_mut!((*slot).b))
 //!             };
-//!             ::core::mem::forget(b);
-//!             ::core::mem::forget(a);
+//!             ::core::mem::forget(__b_guard);
+//!             ::core::mem::forget(__a_guard);
 //!             #[allow(unreachable_code, clippy::diverging_sub_expression)]
 //!             let _ = || {
 //!                 unsafe {
@@ -538,6 +538,7 @@ macro_rules! __pin_data {
         ),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @body({ $($fields:tt)* }),
     ) => {
         // We now use token munching to iterate through all of the fields. While doing this we
@@ -560,6 +561,9 @@ macro_rules! __pin_data {
             @impl_generics($($impl_generics)*),
             // The 'ty generics', the generics that will need to be specified on the impl blocks.
             @ty_generics($($ty_generics)*),
+            // The 'decl generics', the generics that need to be specified on the struct
+            // definition.
+            @decl_generics($($decl_generics)*),
             // The where clause of any impl block and the declaration.
             @where($($($whr)*)?),
             // The remaining fields tokens that need to be processed.
@@ -585,6 +589,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We found a PhantomPinned field, this should generally be pinned!
         @fields_munch($field:ident : $($($(::)?core::)?marker::)?PhantomPinned, $($rest:tt)*),
@@ -607,6 +612,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($($rest)*),
             @pinned($($pinned)* $($accum)* $field: ::core::marker::PhantomPinned,),
@@ -623,6 +629,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We reached the field declaration.
         @fields_munch($field:ident : $type:ty, $($rest:tt)*),
@@ -640,6 +647,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($($rest)*),
             @pinned($($pinned)* $($accum)* $field: $type,),
@@ -656,6 +664,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We reached the field declaration.
         @fields_munch($field:ident : $type:ty, $($rest:tt)*),
@@ -673,6 +682,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($($rest)*),
             @pinned($($pinned)*),
@@ -689,6 +699,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We found the `#[pin]` attr.
         @fields_munch(#[pin] $($rest:tt)*),
@@ -705,6 +716,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($($rest)*),
             // We do not include `#[pin]` in the list of attributes, since it is not actually an
@@ -724,6 +736,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We reached the field declaration with visibility, for simplicity we only munch the
         // visibility and put it into `$accum`.
@@ -741,6 +754,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($field $($rest)*),
             @pinned($($pinned)*),
@@ -757,6 +771,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // Some other attribute, just put it into `$accum`.
         @fields_munch(#[$($attr:tt)*] $($rest:tt)*),
@@ -773,6 +788,7 @@ macro_rules! __pin_data {
             @name($name),
             @impl_generics($($impl_generics)*),
             @ty_generics($($ty_generics)*),
+            @decl_generics($($decl_generics)*),
             @where($($whr)*),
             @fields_munch($($rest)*),
             @pinned($($pinned)*),
@@ -789,6 +805,7 @@ macro_rules! __pin_data {
         @name($name:ident),
         @impl_generics($($impl_generics:tt)*),
         @ty_generics($($ty_generics:tt)*),
+        @decl_generics($($decl_generics:tt)*),
         @where($($whr:tt)*),
         // We reached the end of the fields, plus an optional additional comma, since we added one
         // before and the user is also allowed to put a trailing comma.
@@ -802,7 +819,7 @@ macro_rules! __pin_data {
     ) => {
         // Declare the struct with all fields in the correct order.
         $($struct_attrs)*
-        $vis struct $name <$($impl_generics)*>
+        $vis struct $name <$($decl_generics)*>
         where $($whr)*
         {
             $($fields)*
@@ -1192,14 +1209,14 @@ macro_rules! __init_internal {
         // We use `paste!` to create new hygiene for `$field`.
         ::kernel::macros::paste! {
             // SAFETY: We forget the guard later when initialization has succeeded.
-            let [<$field>] = unsafe {
+            let [< __ $field _guard >] = unsafe {
                 $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field))
             };
 
             $crate::__init_internal!(init_slot($use_data):
                 @data($data),
                 @slot($slot),
-                @guards([<$field>], $($guards,)*),
+                @guards([< __ $field _guard >], $($guards,)*),
                 @munch_fields($($rest)*),
             );
         }
@@ -1223,14 +1240,14 @@ macro_rules! __init_internal {
         // We use `paste!` to create new hygiene for `$field`.
         ::kernel::macros::paste! {
             // SAFETY: We forget the guard later when initialization has succeeded.
-            let [<$field>] = unsafe {
+            let [< __ $field _guard >] = unsafe {
                 $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field))
             };
 
             $crate::__init_internal!(init_slot():
                 @data($data),
                 @slot($slot),
-                @guards([<$field>], $($guards,)*),
+                @guards([< __ $field _guard >], $($guards,)*),
                 @munch_fields($($rest)*),
             );
         }
@@ -1255,14 +1272,14 @@ macro_rules! __init_internal {
         // We use `paste!` to create new hygiene for `$field`.
         ::kernel::macros::paste! {
             // SAFETY: We forget the guard later when initialization has succeeded.
-            let [<$field>] = unsafe {
+            let [< __ $field _guard >] = unsafe {
                 $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_mut!((*$slot).$field))
             };
 
             $crate::__init_internal!(init_slot($($use_data)?):
                 @data($data),
                 @slot($slot),
-                @guards([<$field>], $($guards,)*),
+                @guards([< __ $field _guard >], $($guards,)*),
                 @munch_fields($($rest)*),
             );
         }
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index be68d5e567b1..fbd91a48ff8b 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -12,11 +12,9 @@
 //! do so first instead of bypassing this crate.
 
 #![no_std]
-#![feature(allocator_api)]
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
 #![feature(new_uninit)]
-#![feature(offset_of)]
 #![feature(receiver_trait)]
 #![feature(unsize)]
 
@@ -28,9 +26,7 @@ compile_error!("Missing kernel configuration for conditional compilation");
 // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
 extern crate self as kernel;
 
-#[cfg(not(test))]
-#[cfg(not(testlib))]
-mod allocator;
+pub mod alloc;
 mod build_assert;
 pub mod error;
 pub mod init;
@@ -65,7 +61,7 @@ const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
 /// The top level entrypoint to implementing a kernel module.
 ///
 /// For any teardown or cleanup operations, your type may implement [`Drop`].
-pub trait Module: Sized + Sync {
+pub trait Module: Sized + Sync + Send {
     /// Called at module initialization time.
     ///
     /// Use this method to perform whatever setup or registration your module
@@ -92,6 +88,13 @@ impl ThisModule {
     pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
         ThisModule(ptr)
     }
+
+    /// Access the raw pointer for this module.
+    ///
+    /// It is up to the user to use it correctly.
+    pub const fn as_ptr(&self) -> *mut bindings::module {
+        self.0
+    }
 }
 
 #[cfg(not(any(testlib, test)))]
diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 96e09c6e8530..fd40b703d224 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -6,7 +6,7 @@
 //!
 //! C headers: [`include/linux/phy.h`](srctree/include/linux/phy.h).
 
-use crate::{bindings, error::*, prelude::*, str::CStr, types::Opaque};
+use crate::{error::*, prelude::*, types::Opaque};
 
 use core::marker::PhantomData;
 
@@ -640,6 +640,10 @@ pub struct Registration {
     drivers: Pin<&'static mut [DriverVTable]>,
 }
 
+// SAFETY: The only action allowed in a `Registration` instance is dropping it, which is safe to do
+// from any thread because `phy_drivers_unregister` can be called from any thread context.
+unsafe impl Send for Registration {}
+
 impl Registration {
     /// Registers a PHY driver.
     pub fn register(
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index ae21600970b3..b37a0b3180fb 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,6 +14,8 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
+pub use crate::alloc::{box_ext::BoxExt, flags::*, vec_ext::VecExt};
+
 #[doc(no_inline)]
 pub use alloc::{boxed::Box, vec::Vec};
 
diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
index 9b13aca832c2..a78aa3514a0a 100644
--- a/rust/kernel/print.rs
+++ b/rust/kernel/print.rs
@@ -13,9 +13,6 @@ use core::{
 
 use crate::str::RawFormatter;
 
-#[cfg(CONFIG_PRINTK)]
-use crate::bindings;
-
 // Called from `vsprintf` with format specifier `%pA`.
 #[no_mangle]
 unsafe extern "C" fn rust_fmt_argument(
@@ -35,8 +32,6 @@ unsafe extern "C" fn rust_fmt_argument(
 /// Public but hidden since it should only be used from public macros.
 #[doc(hidden)]
 pub mod format_strings {
-    use crate::bindings;
-
     /// The length we copy from the `KERN_*` kernel prefixes.
     const LENGTH_PREFIX: usize = 2;
 
diff --git a/rust/kernel/std_vendor.rs b/rust/kernel/std_vendor.rs
index 388d6a5147a2..39679a960c1a 100644
--- a/rust/kernel/std_vendor.rs
+++ b/rust/kernel/std_vendor.rs
@@ -146,15 +146,16 @@ macro_rules! dbg {
     // `$val` expression could be a block (`{ .. }`), in which case the `pr_info!`
     // will be malformed.
     () => {
-        $crate::pr_info!("[{}:{}]\n", ::core::file!(), ::core::line!())
+        $crate::pr_info!("[{}:{}:{}]\n", ::core::file!(), ::core::line!(), ::core::column!())
     };
     ($val:expr $(,)?) => {
         // Use of `match` here is intentional because it affects the lifetimes
         // of temporaries - https://stackoverflow.com/a/48732525/1063961
         match $val {
             tmp => {
-                $crate::pr_info!("[{}:{}] {} = {:#?}\n",
-                    ::core::file!(), ::core::line!(), ::core::stringify!($val), &tmp);
+                $crate::pr_info!("[{}:{}:{}] {} = {:#?}\n",
+                    ::core::file!(), ::core::line!(), ::core::column!(),
+                    ::core::stringify!($val), &tmp);
                 tmp
             }
         }
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 925ced8fdc61..bb8d4f41475b 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,15 +2,12 @@
 
 //! String representations.
 
-use alloc::alloc::AllocError;
+use crate::alloc::{flags::*, vec_ext::VecExt, AllocError};
 use alloc::vec::Vec;
 use core::fmt::{self, Write};
-use core::ops::{self, Deref, Index};
+use core::ops::{self, Deref, DerefMut, Index};
 
-use crate::{
-    bindings,
-    error::{code::*, Error},
-};
+use crate::error::{code::*, Error};
 
 /// Byte string without UTF-8 validity guarantee.
 #[repr(transparent)]
@@ -236,6 +233,19 @@ impl CStr {
         unsafe { core::mem::transmute(bytes) }
     }
 
+    /// Creates a mutable [`CStr`] from a `[u8]` without performing any
+    /// additional checks.
+    ///
+    /// # Safety
+    ///
+    /// `bytes` *must* end with a `NUL` byte, and should only have a single
+    /// `NUL` byte (or the string will be truncated).
+    #[inline]
+    pub unsafe fn from_bytes_with_nul_unchecked_mut(bytes: &mut [u8]) -> &mut CStr {
+        // SAFETY: Properties of `bytes` guaranteed by the safety precondition.
+        unsafe { &mut *(bytes as *mut [u8] as *mut CStr) }
+    }
+
     /// Returns a C pointer to the string.
     #[inline]
     pub const fn as_char_ptr(&self) -> *const core::ffi::c_char {
@@ -299,6 +309,70 @@ impl CStr {
     pub fn to_cstring(&self) -> Result<CString, AllocError> {
         CString::try_from(self)
     }
+
+    /// Converts this [`CStr`] to its ASCII lower case equivalent in-place.
+    ///
+    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To return a new lowercased value without modifying the existing one, use
+    /// [`to_ascii_lowercase()`].
+    ///
+    /// [`to_ascii_lowercase()`]: #method.to_ascii_lowercase
+    pub fn make_ascii_lowercase(&mut self) {
+        // INVARIANT: This doesn't introduce or remove NUL bytes in the C
+        // string.
+        self.0.make_ascii_lowercase();
+    }
+
+    /// Converts this [`CStr`] to its ASCII upper case equivalent in-place.
+    ///
+    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To return a new uppercased value without modifying the existing one, use
+    /// [`to_ascii_uppercase()`].
+    ///
+    /// [`to_ascii_uppercase()`]: #method.to_ascii_uppercase
+    pub fn make_ascii_uppercase(&mut self) {
+        // INVARIANT: This doesn't introduce or remove NUL bytes in the C
+        // string.
+        self.0.make_ascii_uppercase();
+    }
+
+    /// Returns a copy of this [`CString`] where each character is mapped to its
+    /// ASCII lower case equivalent.
+    ///
+    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To lowercase the value in-place, use [`make_ascii_lowercase`].
+    ///
+    /// [`make_ascii_lowercase`]: str::make_ascii_lowercase
+    pub fn to_ascii_lowercase(&self) -> Result<CString, AllocError> {
+        let mut s = self.to_cstring()?;
+
+        s.make_ascii_lowercase();
+
+        Ok(s)
+    }
+
+    /// Returns a copy of this [`CString`] where each character is mapped to its
+    /// ASCII upper case equivalent.
+    ///
+    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
+    /// but non-ASCII letters are unchanged.
+    ///
+    /// To uppercase the value in-place, use [`make_ascii_uppercase`].
+    ///
+    /// [`make_ascii_uppercase`]: str::make_ascii_uppercase
+    pub fn to_ascii_uppercase(&self) -> Result<CString, AllocError> {
+        let mut s = self.to_cstring()?;
+
+        s.make_ascii_uppercase();
+
+        Ok(s)
+    }
 }
 
 impl fmt::Display for CStr {
@@ -729,7 +803,7 @@ impl CString {
         let size = f.bytes_written();
 
         // Allocate a vector with the required number of bytes, and write to it.
-        let mut buf = Vec::try_with_capacity(size)?;
+        let mut buf = <Vec<_> as VecExt<_>>::with_capacity(size, GFP_KERNEL)?;
         // SAFETY: The buffer stored in `buf` is at least of size `size` and is valid for writes.
         let mut f = unsafe { Formatter::from_buffer(buf.as_mut_ptr(), size) };
         f.write_fmt(args)?;
@@ -764,13 +838,21 @@ impl Deref for CString {
     }
 }
 
+impl DerefMut for CString {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        // SAFETY: A `CString` is always NUL-terminated and contains no other
+        // NUL bytes.
+        unsafe { CStr::from_bytes_with_nul_unchecked_mut(self.buf.as_mut_slice()) }
+    }
+}
+
 impl<'a> TryFrom<&'a CStr> for CString {
     type Error = AllocError;
 
     fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
         let mut buf = Vec::new();
 
-        buf.try_extend_from_slice(cstr.as_bytes_with_nul())
+        <Vec<_> as VecExt<_>>::extend_from_slice(&mut buf, cstr.as_bytes_with_nul(), GFP_KERNEL)
             .map_err(|_| AllocError)?;
 
         // INVARIANT: The `CStr` and `CString` types have the same invariants for
diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs
index c983f63fd56e..0ab20975a3b5 100644
--- a/rust/kernel/sync.rs
+++ b/rust/kernel/sync.rs
@@ -37,6 +37,12 @@ impl LockClassKey {
     }
 }
 
+impl Default for LockClassKey {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
 /// Defines a new static lock class and returns a pointer to it.
 #[doc(hidden)]
 #[macro_export]
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 7d4c4bf58388..3673496c2363 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -16,7 +16,7 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
-    bindings,
+    alloc::{box_ext::BoxExt, AllocError, Flags},
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
     try_init,
@@ -24,7 +24,7 @@ use crate::{
 };
 use alloc::boxed::Box;
 use core::{
-    alloc::{AllocError, Layout},
+    alloc::Layout,
     fmt,
     marker::{PhantomData, Unsize},
     mem::{ManuallyDrop, MaybeUninit},
@@ -57,7 +57,7 @@ mod std_vendor;
 /// }
 ///
 /// // Create a refcounted instance of `Example`.
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///
 /// // Get a new pointer to `obj` and increment the refcount.
 /// let cloned = obj.clone();
@@ -96,7 +96,7 @@ mod std_vendor;
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.use_reference();
 /// obj.take_over();
 /// # Ok::<(), Error>(())
@@ -119,7 +119,7 @@ mod std_vendor;
 /// impl MyTrait for Example {}
 ///
 /// // `obj` has type `Arc<Example>`.
-/// let obj: Arc<Example> = Arc::try_new(Example)?;
+/// let obj: Arc<Example> = Arc::new(Example, GFP_KERNEL)?;
 ///
 /// // `coerced` has type `Arc<dyn MyTrait>`.
 /// let coerced: Arc<dyn MyTrait> = obj;
@@ -137,6 +137,39 @@ struct ArcInner<T: ?Sized> {
     data: T,
 }
 
+impl<T: ?Sized> ArcInner<T> {
+    /// Converts a pointer to the contents of an [`Arc`] into a pointer to the [`ArcInner`].
+    ///
+    /// # Safety
+    ///
+    /// `ptr` must have been returned by a previous call to [`Arc::into_raw`], and the `Arc` must
+    /// not yet have been destroyed.
+    unsafe fn container_of(ptr: *const T) -> NonNull<ArcInner<T>> {
+        let refcount_layout = Layout::new::<bindings::refcount_t>();
+        // SAFETY: The caller guarantees that the pointer is valid.
+        let val_layout = Layout::for_value(unsafe { &*ptr });
+        // SAFETY: We're computing the layout of a real struct that existed when compiling this
+        // binary, so its layout is not so large that it can trigger arithmetic overflow.
+        let val_offset = unsafe { refcount_layout.extend(val_layout).unwrap_unchecked().1 };
+
+        // Pointer casts leave the metadata unchanged. This is okay because the metadata of `T` and
+        // `ArcInner<T>` is the same since `ArcInner` is a struct with `T` as its last field.
+        //
+        // This is documented at:
+        // <https://doc.rust-lang.org/std/ptr/trait.Pointee.html>.
+        let ptr = ptr as *const ArcInner<T>;
+
+        // SAFETY: The pointer is in-bounds of an allocation both before and after offsetting the
+        // pointer, since it originates from a previous call to `Arc::into_raw` on an `Arc` that is
+        // still valid.
+        let ptr = unsafe { ptr.byte_sub(val_offset) };
+
+        // SAFETY: The pointer can't be null since you can't have an `ArcInner<T>` value at the null
+        // address.
+        unsafe { NonNull::new_unchecked(ptr.cast_mut()) }
+    }
+}
+
 // This is to allow [`Arc`] (and variants) to be used as the type of `self`.
 impl<T: ?Sized> core::ops::Receiver for Arc<T> {}
 
@@ -162,7 +195,7 @@ unsafe impl<T: ?Sized + Sync + Send> Sync for Arc<T> {}
 
 impl<T> Arc<T> {
     /// Constructs a new reference counted instance of `T`.
-    pub fn try_new(contents: T) -> Result<Self, AllocError> {
+    pub fn new(contents: T, flags: Flags) -> Result<Self, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
         let value = ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.
@@ -170,7 +203,7 @@ impl<T> Arc<T> {
             data: contents,
         };
 
-        let inner = Box::try_new(value)?;
+        let inner = <Box<_> as BoxExt<_>>::new(value, flags)?;
 
         // SAFETY: We just created `inner` with a reference count of 1, which is owned by the new
         // `Arc` object.
@@ -181,22 +214,22 @@ impl<T> Arc<T> {
     ///
     /// If `T: !Unpin` it will not be able to move afterwards.
     #[inline]
-    pub fn pin_init<E>(init: impl PinInit<T, E>) -> error::Result<Self>
+    pub fn pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
-        UniqueArc::pin_init(init).map(|u| u.into())
+        UniqueArc::pin_init(init, flags).map(|u| u.into())
     }
 
     /// Use the given initializer to in-place initialize a `T`.
     ///
     /// This is equivalent to [`Arc<T>::pin_init`], since an [`Arc`] is always pinned.
     #[inline]
-    pub fn init<E>(init: impl Init<T, E>) -> error::Result<Self>
+    pub fn init<E>(init: impl Init<T, E>, flags: Flags) -> error::Result<Self>
     where
         Error: From<E>,
     {
-        UniqueArc::init(init).map(|u| u.into())
+        UniqueArc::init(init, flags).map(|u| u.into())
     }
 }
 
@@ -232,27 +265,13 @@ impl<T: ?Sized> Arc<T> {
     /// `ptr` must have been returned by a previous call to [`Arc::into_raw`]. Additionally, it
     /// must not be called more than once for each previous call to [`Arc::into_raw`].
     pub unsafe fn from_raw(ptr: *const T) -> Self {
-        let refcount_layout = Layout::new::<bindings::refcount_t>();
-        // SAFETY: The caller guarantees that the pointer is valid.
-        let val_layout = Layout::for_value(unsafe { &*ptr });
-        // SAFETY: We're computing the layout of a real struct that existed when compiling this
-        // binary, so its layout is not so large that it can trigger arithmetic overflow.
-        let val_offset = unsafe { refcount_layout.extend(val_layout).unwrap_unchecked().1 };
-
-        // Pointer casts leave the metadata unchanged. This is okay because the metadata of `T` and
-        // `ArcInner<T>` is the same since `ArcInner` is a struct with `T` as its last field.
-        //
-        // This is documented at:
-        // <https://doc.rust-lang.org/std/ptr/trait.Pointee.html>.
-        let ptr = ptr as *const ArcInner<T>;
-
-        // SAFETY: The pointer is in-bounds of an allocation both before and after offsetting the
-        // pointer, since it originates from a previous call to `Arc::into_raw` and is still valid.
-        let ptr = unsafe { ptr.byte_sub(val_offset) };
+        // SAFETY: The caller promises that this pointer originates from a call to `into_raw` on an
+        // `Arc` that is still valid.
+        let ptr = unsafe { ArcInner::container_of(ptr) };
 
         // SAFETY: By the safety requirements we know that `ptr` came from `Arc::into_raw`, so the
         // reference count held then will be owned by the new `Arc` object.
-        unsafe { Self::from_inner(NonNull::new_unchecked(ptr.cast_mut())) }
+        unsafe { Self::from_inner(ptr) }
     }
 
     /// Returns an [`ArcBorrow`] from the given [`Arc`].
@@ -271,6 +290,68 @@ impl<T: ?Sized> Arc<T> {
     pub fn ptr_eq(this: &Self, other: &Self) -> bool {
         core::ptr::eq(this.ptr.as_ptr(), other.ptr.as_ptr())
     }
+
+    /// Converts this [`Arc`] into a [`UniqueArc`], or destroys it if it is not unique.
+    ///
+    /// When this destroys the `Arc`, it does so while properly avoiding races. This means that
+    /// this method will never call the destructor of the value.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use kernel::sync::{Arc, UniqueArc};
+    ///
+    /// let arc = Arc::new(42, GFP_KERNEL)?;
+    /// let unique_arc = arc.into_unique_or_drop();
+    ///
+    /// // The above conversion should succeed since refcount of `arc` is 1.
+    /// assert!(unique_arc.is_some());
+    ///
+    /// assert_eq!(*(unique_arc.unwrap()), 42);
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    ///
+    /// ```
+    /// use kernel::sync::{Arc, UniqueArc};
+    ///
+    /// let arc = Arc::new(42, GFP_KERNEL)?;
+    /// let another = arc.clone();
+    ///
+    /// let unique_arc = arc.into_unique_or_drop();
+    ///
+    /// // The above conversion should fail since refcount of `arc` is >1.
+    /// assert!(unique_arc.is_none());
+    ///
+    /// # Ok::<(), Error>(())
+    /// ```
+    pub fn into_unique_or_drop(self) -> Option<Pin<UniqueArc<T>>> {
+        // We will manually manage the refcount in this method, so we disable the destructor.
+        let me = ManuallyDrop::new(self);
+        // SAFETY: We own a refcount, so the pointer is still valid.
+        let refcount = unsafe { me.ptr.as_ref() }.refcount.get();
+
+        // If the refcount reaches a non-zero value, then we have destroyed this `Arc` and will
+        // return without further touching the `Arc`. If the refcount reaches zero, then there are
+        // no other arcs, and we can create a `UniqueArc`.
+        //
+        // SAFETY: We own a refcount, so the pointer is not dangling.
+        let is_zero = unsafe { bindings::refcount_dec_and_test(refcount) };
+        if is_zero {
+            // SAFETY: We have exclusive access to the arc, so we can perform unsynchronized
+            // accesses to the refcount.
+            unsafe { core::ptr::write(refcount, bindings::REFCOUNT_INIT(1)) };
+
+            // INVARIANT: We own the only refcount to this arc, so we may create a `UniqueArc`. We
+            // must pin the `UniqueArc` because the values was previously in an `Arc`, and they pin
+            // their values.
+            Some(Pin::from(UniqueArc {
+                inner: ManuallyDrop::into_inner(me),
+            }))
+        } else {
+            None
+        }
+    }
 }
 
 impl<T: 'static> ForeignOwnable for Arc<T> {
@@ -387,7 +468,7 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> {
 ///     e.into()
 /// }
 ///
-/// let obj = Arc::try_new(Example)?;
+/// let obj = Arc::new(Example, GFP_KERNEL)?;
 /// let cloned = do_something(obj.as_arc_borrow());
 ///
 /// // Assert that both `obj` and `cloned` point to the same underlying object.
@@ -411,7 +492,7 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> {
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.as_arc_borrow().use_reference();
 /// # Ok::<(), Error>(())
 /// ```
@@ -453,6 +534,27 @@ impl<T: ?Sized> ArcBorrow<'_, T> {
             _p: PhantomData,
         }
     }
+
+    /// Creates an [`ArcBorrow`] to an [`Arc`] that has previously been deconstructed with
+    /// [`Arc::into_raw`].
+    ///
+    /// # Safety
+    ///
+    /// * The provided pointer must originate from a call to [`Arc::into_raw`].
+    /// * For the duration of the lifetime annotated on this `ArcBorrow`, the reference count must
+    ///   not hit zero.
+    /// * For the duration of the lifetime annotated on this `ArcBorrow`, there must not be a
+    ///   [`UniqueArc`] reference to this value.
+    pub unsafe fn from_raw(ptr: *const T) -> Self {
+        // SAFETY: The caller promises that this pointer originates from a call to `into_raw` on an
+        // `Arc` that is still valid.
+        let ptr = unsafe { ArcInner::container_of(ptr) };
+
+        // SAFETY: The caller promises that the value remains valid since the reference count must
+        // not hit zero, and no mutable reference will be created since that would involve a
+        // `UniqueArc`.
+        unsafe { Self::new(ptr) }
+    }
 }
 
 impl<T: ?Sized> From<ArcBorrow<'_, T>> for Arc<T> {
@@ -499,7 +601,7 @@ impl<T: ?Sized> Deref for ArcBorrow<'_, T> {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut x = UniqueArc::try_new(Example { a: 10, b: 20 })?;
+///     let mut x = UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///     x.a += 1;
 ///     x.b += 1;
 ///     Ok(x.into())
@@ -522,7 +624,7 @@ impl<T: ?Sized> Deref for ArcBorrow<'_, T> {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let x = UniqueArc::try_new_uninit()?;
+///     let x = UniqueArc::new_uninit(GFP_KERNEL)?;
 ///     Ok(x.write(Example { a: 10, b: 20 }).into())
 /// }
 ///
@@ -542,7 +644,7 @@ impl<T: ?Sized> Deref for ArcBorrow<'_, T> {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut pinned = Pin::from(UniqueArc::try_new(Example { a: 10, b: 20 })?);
+///     let mut pinned = Pin::from(UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?);
 ///     // We can modify `pinned` because it is `Unpin`.
 ///     pinned.as_mut().a += 1;
 ///     Ok(pinned.into())
@@ -556,21 +658,24 @@ pub struct UniqueArc<T: ?Sized> {
 
 impl<T> UniqueArc<T> {
     /// Tries to allocate a new [`UniqueArc`] instance.
-    pub fn try_new(value: T) -> Result<Self, AllocError> {
+    pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
         Ok(Self {
             // INVARIANT: The newly-created object has a refcount of 1.
-            inner: Arc::try_new(value)?,
+            inner: Arc::new(value, flags)?,
         })
     }
 
     /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
-    pub fn try_new_uninit() -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
+    pub fn new_uninit(flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
-        let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
-            // SAFETY: There are no safety requirements for this FFI call.
-            refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
-            data <- init::uninit::<T, AllocError>(),
-        }? AllocError))?;
+        let inner = Box::try_init::<AllocError>(
+            try_init!(ArcInner {
+                // SAFETY: There are no safety requirements for this FFI call.
+                refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }),
+                data <- init::uninit::<T, AllocError>(),
+            }? AllocError),
+            flags,
+        )?;
         Ok(UniqueArc {
             // INVARIANT: The newly-created object has a refcount of 1.
             // SAFETY: The pointer from the `Box` is valid.
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index 0c3671caffeb..2b306afbe56d 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -7,7 +7,6 @@
 
 use super::{lock::Backend, lock::Guard, LockClassKey};
 use crate::{
-    bindings,
     init::PinInit,
     pin_init,
     str::CStr,
@@ -75,7 +74,7 @@ pub use new_condvar;
 ///     Box::pin_init(pin_init!(Example {
 ///         value <- new_mutex!(0),
 ///         value_changed <- new_condvar!(),
-///     }))
+///     }), GFP_KERNEL)
 /// }
 /// ```
 ///
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 5b5c8efe427a..f6c34ca4d819 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -6,7 +6,7 @@
 //! spinlocks, raw spinlocks) to be provided with minimal effort.
 
 use super::LockClassKey;
-use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard};
+use crate::{init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard};
 use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned};
 use macros::pin_data;
 
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index ef4c4634d294..30632070ee67 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs
@@ -4,8 +4,6 @@
 //!
 //! This module allows Rust code to use the kernel's `struct mutex`.
 
-use crate::bindings;
-
 /// Creates a [`Mutex`] initialiser with the given name and a newly-created lock class.
 ///
 /// It uses the name if one is given, otherwise it generates one based on the file name and line
@@ -60,7 +58,7 @@ pub use new_mutex;
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new())?;
+/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index 0b22c635634f..ea5c5bc1ce12 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs
@@ -4,8 +4,6 @@
 //!
 //! This module allows Rust code to use the kernel's `spinlock_t`.
 
-use crate::bindings;
-
 /// Creates a [`SpinLock`] initialiser with the given name and a newly-created lock class.
 ///
 /// It uses the name if one is given, otherwise it generates one based on the file name and line
@@ -58,7 +56,7 @@ pub use new_spinlock;
 /// }
 ///
 /// // Allocate a boxed `Example`.
-/// let e = Box::pin_init(Example::new())?;
+/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?;
 /// assert_eq!(e.c, 10);
 /// assert_eq!(e.d.lock().a, 20);
 /// assert_eq!(e.d.lock().b, 30);
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index ca6e7e31d71c..55dff7e088bf 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -4,7 +4,7 @@
 //!
 //! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
 
-use crate::{bindings, types::Opaque};
+use crate::types::Opaque;
 use core::{
     ffi::{c_int, c_long, c_uint},
     marker::PhantomData,
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index 25a896eed468..e3bb5e89f88d 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -4,6 +4,12 @@
 //!
 //! This module contains the kernel APIs related to time and timers that
 //! have been ported or wrapped for usage by Rust code in the kernel.
+//!
+//! C header: [`include/linux/jiffies.h`](srctree/include/linux/jiffies.h).
+//! C header: [`include/linux/ktime.h`](srctree/include/linux/ktime.h).
+
+/// The number of nanoseconds per millisecond.
+pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
 
 /// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
 pub type Jiffies = core::ffi::c_ulong;
@@ -18,3 +24,60 @@ pub fn msecs_to_jiffies(msecs: Msecs) -> Jiffies {
     // matter what the argument is.
     unsafe { bindings::__msecs_to_jiffies(msecs) }
 }
+
+/// A Rust wrapper around a `ktime_t`.
+#[repr(transparent)]
+#[derive(Copy, Clone)]
+pub struct Ktime {
+    inner: bindings::ktime_t,
+}
+
+impl Ktime {
+    /// Create a `Ktime` from a raw `ktime_t`.
+    #[inline]
+    pub fn from_raw(inner: bindings::ktime_t) -> Self {
+        Self { inner }
+    }
+
+    /// Get the current time using `CLOCK_MONOTONIC`.
+    #[inline]
+    pub fn ktime_get() -> Self {
+        // SAFETY: It is always safe to call `ktime_get` outside of NMI context.
+        Self::from_raw(unsafe { bindings::ktime_get() })
+    }
+
+    /// Divide the number of nanoseconds by a compile-time constant.
+    #[inline]
+    fn divns_constant<const DIV: i64>(self) -> i64 {
+        self.to_ns() / DIV
+    }
+
+    /// Returns the number of nanoseconds.
+    #[inline]
+    pub fn to_ns(self) -> i64 {
+        self.inner
+    }
+
+    /// Returns the number of milliseconds.
+    #[inline]
+    pub fn to_ms(self) -> i64 {
+        self.divns_constant::<NSEC_PER_MSEC>()
+    }
+}
+
+/// Returns the number of milliseconds between two ktimes.
+#[inline]
+pub fn ktime_ms_delta(later: Ktime, earlier: Ktime) -> i64 {
+    (later - earlier).to_ms()
+}
+
+impl core::ops::Sub for Ktime {
+    type Output = Ktime;
+
+    #[inline]
+    fn sub(self, other: Ktime) -> Ktime {
+        Self {
+            inner: self.inner - other.inner,
+        }
+    }
+}
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index aa77bad9bce4..2e7c9008621f 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -157,11 +157,11 @@ impl ForeignOwnable for () {
 ///     let mut vec =
 ///         ScopeGuard::new_with_data(Vec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
 ///
-///     vec.try_push(10u8)?;
+///     vec.push(10u8, GFP_KERNEL)?;
 ///     if arg {
 ///         return Ok(());
 ///     }
-///     vec.try_push(20u8)?;
+///     vec.push(20u8, GFP_KERNEL)?;
 ///     Ok(())
 /// }
 ///
@@ -270,7 +270,7 @@ impl<T> Opaque<T> {
     }
 
     /// Returns a raw pointer to the opaque data.
-    pub fn get(&self) -> *mut T {
+    pub const fn get(&self) -> *mut T {
         UnsafeCell::get(&self.value).cast::<T>()
     }
 
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 480cb292e7c2..1cec63a2aea8 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -33,7 +33,6 @@
 //! we do not need to specify ids for the fields.
 //!
 //! ```
-//! use kernel::prelude::*;
 //! use kernel::sync::Arc;
 //! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
 //!
@@ -53,7 +52,7 @@
 //!         Arc::pin_init(pin_init!(MyStruct {
 //!             value,
 //!             work <- new_work!("MyStruct::work"),
-//!         }))
+//!         }), GFP_KERNEL)
 //!     }
 //! }
 //!
@@ -75,7 +74,6 @@
 //! The following example shows how multiple `work_struct` fields can be used:
 //!
 //! ```
-//! use kernel::prelude::*;
 //! use kernel::sync::Arc;
 //! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
 //!
@@ -101,7 +99,7 @@
 //!             value_2,
 //!             work_1 <- new_work!("MyStruct::work_1"),
 //!             work_2 <- new_work!("MyStruct::work_2"),
-//!         }))
+//!         }), GFP_KERNEL)
 //!     }
 //! }
 //!
@@ -132,11 +130,9 @@
 //!
 //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
 
-use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
-use alloc::alloc::AllocError;
-use alloc::boxed::Box;
+use crate::alloc::{AllocError, Flags};
+use crate::{prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
 use core::marker::PhantomData;
-use core::pin::Pin;
 
 /// Creates a [`Work`] initialiser with the given name and a newly-created lock class.
 #[macro_export]
@@ -210,13 +206,17 @@ impl Queue {
     /// Tries to spawn the given function or closure as a work item.
     ///
     /// This method can fail because it allocates memory to store the work item.
-    pub fn try_spawn<T: 'static + Send + FnOnce()>(&self, func: T) -> Result<(), AllocError> {
+    pub fn try_spawn<T: 'static + Send + FnOnce()>(
+        &self,
+        flags: Flags,
+        func: T,
+    ) -> Result<(), AllocError> {
         let init = pin_init!(ClosureWork {
             work <- new_work!("Queue::try_spawn"),
             func: Some(func),
         });
 
-        self.enqueue(Box::pin_init(init).map_err(|_| AllocError)?);
+        self.enqueue(Box::pin_init(init, flags).map_err(|_| AllocError)?);
         Ok(())
     }
 }
@@ -346,8 +346,10 @@ pub trait WorkItem<const ID: u64 = 0> {
 /// This is a helper type used to associate a `work_struct` with the [`WorkItem`] that uses it.
 ///
 /// [`run`]: WorkItemPointer::run
+#[pin_data]
 #[repr(transparent)]
 pub struct Work<T: ?Sized, const ID: u64 = 0> {
+    #[pin]
     work: Opaque<bindings::work_struct>,
     _inner: PhantomData<T>,
 }
@@ -369,21 +371,22 @@ impl<T: ?Sized, const ID: u64> Work<T, ID> {
     where
         T: WorkItem<ID>,
     {
-        // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as the work
-        // item function.
-        unsafe {
-            kernel::init::pin_init_from_closure(move |slot| {
-                let slot = Self::raw_get(slot);
-                bindings::init_work_with_key(
-                    slot,
-                    Some(T::Pointer::run),
-                    false,
-                    name.as_char_ptr(),
-                    key.as_ptr(),
-                );
-                Ok(())
-            })
-        }
+        pin_init!(Self {
+            work <- Opaque::ffi_init(|slot| {
+                // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as
+                // the work item function.
+                unsafe {
+                    bindings::init_work_with_key(
+                        slot,
+                        Some(T::Pointer::run),
+                        false,
+                        name.as_char_ptr(),
+                        key.as_ptr(),
+                    )
+                }
+            }),
+            _inner: PhantomData,
+        })
     }
 
     /// Get a pointer to the inner `work_struct`.
@@ -408,7 +411,6 @@ impl<T: ?Sized, const ID: u64> Work<T, ID> {
 /// like this:
 ///
 /// ```no_run
-/// use kernel::prelude::*;
 /// use kernel::workqueue::{impl_has_work, Work};
 ///
 /// struct MyWorkItem {