On 4/28/25 17:28, Lorenzo Stoakes wrote: > Currently VMA allocation, freeing and duplication exist in kernel/fork.c, > which is a violation of separation of concerns, and leaves these functions > exposed to the rest of the kernel when they are in fact internal > implementation details. > > Resolve this by moving this logic to mm, and making it internal to vma.c, > vma.h. > > This also allows us, in future, to provide userland testing around this > functionality. > > We additionally abstract dup_mmap() to mm, being careful to ensure > kernel/fork.c acceses this via the mm internal header so it is not exposed > elsewhere in the kernel. > > As part of this change, also abstract initial stack allocation performed in > __bprm_mm_init() out of fs code into mm via the create_init_stack_vma(), as > this code uses vm_area_alloc() and vm_area_free(). > > In order to do so sensibly, we introduce a new mm/vma_exec.c file, which > contains the code that is shared by mm and exec. This file is added to both > memory mapping and exec sections in MAINTAINERS so both sets of maintainers > can maintain oversight. Note that kernel/fork.c itself belongs to no section. Maybe we could put it somewhere too, maybe also multiple subsystems? I'm thinking something between MM, SCHEDULER, EXEC, perhaps PIDFD?
