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

On Wed, Feb 03, 2021 at 01:15:58PM +0100, Michal Hocko wrote:

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.

Ok.