On Thu, Apr 24, 2025 at 11:30:35PM +0200, David Hildenbrand wrote: > On 24.04.25 23:15, Lorenzo Stoakes wrote: > > There are peculiarities within the kernel where what is very clearly mm > > code is performed elsewhere arbitrarily. > > > > This violates separation of concerns and makes it harder to refactor code > > to make changes to how fundamental initialisation and operation of mm logic > > is performed. > > > > One such case is the creation of the VMA containing the initial stack upon > > execve()'ing a new process. This is currently performed in __bprm_mm_init() > > in fs/exec.c. > > > > Abstract this operation to create_init_stack_vma(). This allows us to limit > > use of vma allocation and free code to fork and mm only. > > > > We previously did the same for the step at which we relocate the initial > > stack VMA downwards via relocate_vma_down(), now we move the initial VMA > > establishment too. > > > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> > > --- > ... > > > +/* > > + * Establish the stack VMA in an execve'd process, located temporarily at the > > + * maximum stack address provided by the architecture. > > + * > > + * We later relocate this downwards in relocate_vma_down(). > > + * > > + * This function is almost certainly NOT what you want for anything other than > > + * early executable initialisation. > > + * > > + * On success, returns 0 and sets *vmap to the stack VMA and *top_mem_p to the > > + * maximum addressable location in the stack (that is capable of storing a > > + * system word of data). > > + * > > + * on failure, returns an error code. > > + */ > > I was about to say, if you already write that much documentation, why not > turn it into kerneldoc? :) But this function is clearly not intended to have > more than one caller, so ... :) Haha yeah, I felt for this case it's probably not necessary, bit of a blurry line on this but as a one-off thing probably ok :P > > Acked-by: David Hildenbrand <david@xxxxxxxxxx> Thanks! Sorry I forgot to say thanks also to Suren for his tag in other email, so will say here - also thanks Suren :) > > -- > Cheers, > > David / dhildenb >
