Ackerley Tng via B4 Relay <[email protected]>
writes:
>
> [...snip...]
>
> +static int kvm_gmem_init_inode(struct inode *inode, loff_t size, u64 flags)
> +{
>
> [...snip...]
>
> + filemap_invalidate_lock(inode->i_mapping);
> + r = mas_store_gfp(&mas, xa_mk_value(attrs), GFP_KERNEL);
Sashiko says using GFP_KERNEL with this attributes maple_tree could
allow a process creating a very fragmented maple tree to consume lots of
memory not charged to some memcg and proposed using GFP_KERNEL_ACCOUNT.
The problem with using GFP_KERNEL_ACCOUNT is that the maple tree nodes
are allocated from a shared kmem_cache maple_node_cache. Allocating the
maple tree nodes using GFP_KERNEL_ACCOUNT would mean that the node could
be reused by other maple trees unrelated to this process, and so the
nodes might long outlive the process using this guest_memfd, keeping the
memcg alive far longer than the VM.
For now I think it's okay to stick with GFP_KERNEL? Does anyone else
have suggestions on how to solve this?
> + filemap_invalidate_unlock(inode->i_mapping);
> +
> + return r;
> +}
>
> [...snip...]
>
