6.12-stable review patch. If anyone has any objections, please let me know.
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From: Tamir Duberstein tamird@gmail.com
commit ff64846bee0e7e3e7bc9363ebad3bab42dd27e24 upstream.
ISO C's `aligned_alloc` is partially implementation-defined; on some systems it inherits stricter requirements from POSIX's `posix_memalign`.
This causes the call added in commit dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") to fail on macOS because it doesn't meet the requirements of `posix_memalign`.
Adjust the call to meet the POSIX requirement and add a comment. This fixes failures in `make rusttest` on macOS.
Acked-by: Danilo Krummrich dakr@kernel.org Cc: stable@vger.kernel.org Fixes: dd09538fb409 ("rust: alloc: implement `Cmalloc` in module allocator_test") Signed-off-by: Tamir Duberstein tamird@gmail.com Reviewed-by: Gary Guo gary@garyguo.net Link: https://lore.kernel.org/r/20250213-aligned-alloc-v7-1-d2a2d0be164b@gmail.com [ Added Cc: stable. - Miguel ] Signed-off-by: Miguel Ojeda ojeda@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- rust/kernel/alloc/allocator_test.rs | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
--- a/rust/kernel/alloc/allocator_test.rs +++ b/rust/kernel/alloc/allocator_test.rs @@ -62,6 +62,24 @@ unsafe impl Allocator for Cmalloc { )); }
+ // ISO C (ISO/IEC 9899:2011) defines `aligned_alloc`: + // + // > The value of alignment shall be a valid alignment supported by the implementation + // [...]. + // + // As an example of the "supported by the implementation" requirement, POSIX.1-2001 (IEEE + // 1003.1-2001) defines `posix_memalign`: + // + // > The value of alignment shall be a power of two multiple of sizeof (void *). + // + // and POSIX-based implementations of `aligned_alloc` inherit this requirement. At the time + // of writing, this is known to be the case on macOS (but not in glibc). + // + // Satisfy the stricter requirement to avoid spurious test failures on some platforms. + let min_align = core::mem::size_of::<*const crate::ffi::c_void>(); + let layout = layout.align_to(min_align).map_err(|_| AllocError)?; + let layout = layout.pad_to_align(); + // SAFETY: Returns either NULL or a pointer to a memory allocation that satisfies or // exceeds the given size and alignment requirements. let dst = unsafe { libc_aligned_alloc(layout.align(), layout.size()) } as *mut u8;