Re: [PATCH v16 06/11] mm: introduce memfd_secret system call to create "secret" memory areas

Michal Hocko
2021-02-03T12:16:22Z

On Thu 21-01-21 14:27:18, Mike Rapoport wrote:
> +static struct file *secretmem_file_create(unsigned long flags)
> +{
> + struct file *file = ERR_PTR(-ENOMEM);
> + struct secretmem_ctx *ctx;
> + struct inode *inode;
> +
> + inode = alloc_anon_inode(secretmem_mnt->mnt_sb);
> + if (IS_ERR(inode))
> + return ERR_CAST(inode);
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + goto err_free_inode;
> +
> + file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem",
> + O_RDWR, &secretmem_fops);
> + if (IS_ERR(file))
> + goto err_free_ctx;
> +
> + mapping_set_unevictable(inode->i_mapping);

Btw. you need also mapping_set_gfp_mask(mapping, GFP_HIGHUSER) because
the default is GFP_HIGHUSER_MOVABLE and you do not support migration so
no pages from movable zones should be allowed.

--
Michal Hocko
SUSE Labs