On Tue, Oct 20, 2020 at 09:18:54AM +0300, Kirill A. Shutemov wrote:
> +int __kvm_protect_memory(unsigned long start, unsigned long end, bool protect)
> +{
> + struct mm_struct *mm = current->mm;
> + struct vm_area_struct *vma, *prev;
> + int ret;
> +
> + if (mmap_write_lock_killable(mm))
> + return -EINTR;
> +
> + ret = -ENOMEM;
> + vma = find_vma(current->mm, start);
> + if (!vma)
> + goto out;
> +
> + ret = -EINVAL;
> + if (vma->vm_start > start)
> + goto out;
> +
> + if (start > vma->vm_start)
> + prev = vma;
> + else
> + prev = vma->vm_prev;
> +
> + ret = 0;
> + while (true) {
> + unsigned long newflags, tmp;
> +
> + tmp = vma->vm_end;
> + if (tmp > end)
> + tmp = end;
> +
> + newflags = vma->vm_flags;
> + if (protect)
> + newflags |= VM_KVM_PROTECTED;
> + else
> + newflags &= ~VM_KVM_PROTECTED;
> +
> + /* The VMA has been handled as part of other memslot */
> + if (newflags == vma->vm_flags)
> + goto next;
> +
> + ret = mprotect_fixup(vma, &prev, start, tmp, newflags);
> + if (ret)
> + goto out;
> +
> +next:
> + start = tmp;
> + if (start < prev->vm_end)
> + start = prev->vm_end;
> +
> + if (start >= end)
> + goto out;
> +
> + vma = prev->vm_next;
> + if (!vma || vma->vm_start != start) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + }
> +out:
> + mmap_write_unlock(mm);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(__kvm_protect_memory);
Since migration will be disabled after this; should the above not (at
the very least) force compaction before proceeding to lock the pages in?
