On Wed, Aug 28, 2024 at 04:52:07PM GMT, Liam R. Howlett wrote:
[snip]
> > + /*
> > + * Now try to expand adjacent VMA(s). This takes care of removing the
> > + * following VMA if we have VMAs on both sides.
> > + */
> > + if (vmg->vma && !vma_expand(vmg)) {
> > + khugepaged_enter_vma(vmg->vma, vmg->flags);
>
> This might be able to be moved into vma_expand().
Sorry for the multiple emails, but am working my way through.
Can't do this, as relocate_vma_down() (and the original implementation in
fs/exec.c - I checked) does not invoke khugepaged_enter_vma(), sadly.
>
> > +
>
> Extra whitespace
Ack. A lot of these are to subjective taste for clarity, but am happy to
adjust these for the most part...
>
> > + vmg->state = VMA_MERGE_SUCCESS;
> > + return vmg->vma;
> > + }
> > +
> > + /* If expansion failed, reset state. Allows us to retry merge later. */
> > + vmg->vma = NULL;
> > + vmg->start = start;
> > + vmg->end = end;
> > + vmg->pgoff = pgoff;
> > + if (vmg->vma == prev)
> > + vma_iter_set(vmg->vmi, start);
> > +
> > + return NULL;
> > +}
> > +
> > /*
> > * vma_expand - Expand an existing VMA
> > *
> > @@ -474,7 +584,11 @@ void validate_mm(struct mm_struct *mm)
> > * vmg->next->vm_end. Checking if the vmg->vma can expand and merge with
> > * vmg->next needs to be handled by the caller.
> > *
> > - * Returns: 0 on success
> > + * Returns: 0 on success.
> > + *
> > + * ASSUMPTIONS:
> > + * - The caller must hold a WRITE lock on vmg->vma->mm->mmap_lock.
> > + * - The caller must have set @vmg->vma and @vmg->next.
> > */
> > int vma_expand(struct vma_merge_struct *vmg)
> > {
> > @@ -484,6 +598,8 @@ int vma_expand(struct vma_merge_struct *vmg)
> > struct vm_area_struct *next = vmg->next;
> > struct vma_prepare vp;
> >
> > + mmap_assert_write_locked(vmg->mm);
> > +
>
> There are a few unnecessary whitespaces here..
...except here :) I like to keep the asserts separate from the rest of the
logic, and local declarations on their own lines.
[snip]
