c
    prev = NULL;
    for_each_vma(vmi, vma) {  // Keep the existing loop
        cond_resched();
        BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^
               !!(vma->vm_flags & __VM_UFFD_FLAGS));
        if (vma->vm_userfaultfd_ctx.ctx != ctx) {
            prev = vma;
            continue;
        }

        new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS;
        unsigned long start = vma->vm_start; // Store the start address

        prev = vma_merge(...); // Your existing vma_merge call

        vma = find_vma(mm, start); // Re-acquire the VMA. Might be different or NULL.

        if (vma && vma->vm_userfaultfd_ctx.ctx == ctx) { // Check if it's still relevant
            // Continue processing the (potentially modified or new) VMA
           // ... existing code ...
        }
        // else the VMA was merged out of existence or doesn't belong to ctx.
    }
