Re: [PATCH v1 1/4] mm: Fix uprobe pte be overwritten when expanding vma

On Fri, May 30, 2025 at 08:51:14PM +0200, David Hildenbrand wrote:

...

if (vp->remove) { @@ -1823,6 +1829,14 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, faulted_in_anon_vma = false; }

• /*

• * If the VMA we are copying might contain a uprobe PTE, ensure
  

• * that we do not establish one upon merge. Otherwise, when mremap()
  

• * moves page tables, it will orphan the newly created PTE.
  

• */
  

• if (vma->vm_file)

• vmg.skip_vma_uprobe = true;
  

Assuming we extend the VMA on the way (not merge), would we handle that properly?

Or is that not possible on this code path or already broken either way?

I'm not sure in what context you mean expand, vma_merge_new_range() calls vma_expand() so we call an expand a merge here, and this flag will be obeyed.

vma_merge_new_range() -> vma_expand() -> commit_merge() -> vma_complete() will ensure expected behaviour.

-- Cheers,

David / dhildenb