Re: [PATCH 1/3] mm: introduce VM_MAYBE_GUARD and make visible for guard regions

On 10/29/25 9:50 AM, Lorenzo Stoakes wrote:

diff --git a/mm/memory.c b/mm/memory.c index 4c3a7e09a159..a2c79ee43d68 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1478,6 +1478,10 @@ vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma) if (src_vma->anon_vma) return true;

• /* Guard regions have momdified page tables that require copying. */

modified

• if (src_vma->vm_flags & VM_MAYBE_GUARD)

• return true;
  

• /*
  • Don't copy ptes where a page fault will fill them correctly. Fork
  • becomes much lighter when there are big shared or private readonly