A safer kmalloc() for Linux 7.0
7 hours ago
- #kernel
- #memory-management
- #slab-allocator
- kmalloc() is a general-purpose interface to the slab allocator for small memory chunks in the kernel.
- The kmalloc() API has remained largely unchanged since its introduction in 1992, with minor type adjustments.
- Common errors with kmalloc() include incorrect size allocation due to untyped return values and lack of size checks.
- The 7.0 kernel introduces safer memory allocation functions like kmalloc_obj(), kmalloc_objs(), kzalloc_obj(), and kzalloc_objs().
- New functions provide type safety, eliminate the need for sizeof(), and prevent common allocation mistakes.
- kmalloc_flex() is introduced for structures with flexible array members to ensure correct sizing.
- Large-scale patching converted much of the kernel code to use the new allocation functions.
- Torvalds made the GFP_KERNEL argument optional in the new functions, defaulting to GFP_KERNEL when not specified.
- The changes aim to reduce silly mistakes and improve code readability, though they may cause merge conflicts.