On Wed, May 14, 2025 at 04:42:11PM -0700, Ackerley Tng wrote:
> enum shareability {
> @@ -40,6 +47,44 @@ static struct kvm_gmem_inode_private *kvm_gmem_private(struct inode *inode)
> return inode->i_mapping->i_private_data;
> }
>
> +#ifdef CONFIG_KVM_GMEM_HUGETLB
> +
> +static const struct guestmem_allocator_operations *
> +kvm_gmem_allocator_ops(struct inode *inode)
> +{
> + return kvm_gmem_private(inode)->allocator_ops;
> +}
> +
> +static void *kvm_gmem_allocator_private(struct inode *inode)
> +{
> + return kvm_gmem_private(inode)->allocator_private;
> +}
> +
> +static bool kvm_gmem_has_custom_allocator(struct inode *inode)
> +{
+ if (!kvm_gmem_private(inode))
+ return NULL;
> + return kvm_gmem_allocator_ops(inode) != NULL;
> +}
> +
...
> +static void kvm_gmem_evict_inode(struct inode *inode)
> +{
> + truncate_inode_pages_final_prepare(inode->i_mapping);
> +
> + if (kvm_gmem_has_custom_allocator(inode)) {
The i_private_data of the root inode in pseudo fs is NULL.
Without the two lines added above, evicting the root inode during unmount will
cause NULL pointer deference.
> + size_t nr_pages = inode->i_size >> PAGE_SHIFT;
> +
> + kvm_gmem_truncate_inode_aligned_pages(inode, 0, nr_pages);
> + } else {
> + truncate_inode_pages(inode->i_mapping, 0);
> + }
> +
> + clear_inode(inode);
> +}
> +
> static const struct super_operations kvm_gmem_super_operations = {
> .statfs = simple_statfs,
> + .evict_inode = kvm_gmem_evict_inode,
> .destroy_inode = kvm_gmem_destroy_inode,
> .free_inode = kvm_gmem_free_inode,
> };
