On 29.11.22 12:21, Kirill A. Shutemov wrote:
On Mon, Nov 28, 2022 at 06:06:32PM -0600, Michael Roth wrote:
On Tue, Oct 25, 2022 at 11:13:37PM +0800, Chao Peng wrote:
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
<snip>
+static struct file *restrictedmem_file_create(struct file *memfd)
+{
+ struct restrictedmem_data *data;
+ struct address_space *mapping;
+ struct inode *inode;
+ struct file *file;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return ERR_PTR(-ENOMEM);
+
+ data->memfd = memfd;
+ mutex_init(&data->lock);
+ INIT_LIST_HEAD(&data->notifiers);
+
+ inode = alloc_anon_inode(restrictedmem_mnt->mnt_sb);
+ if (IS_ERR(inode)) {
+ kfree(data);
+ return ERR_CAST(inode);
+ }
+
+ inode->i_mode |= S_IFREG;
+ inode->i_op = &restrictedmem_iops;
+ inode->i_mapping->private_data = data;
+
+ file = alloc_file_pseudo(inode, restrictedmem_mnt,
+ "restrictedmem", O_RDWR,
+ &restrictedmem_fops);
+ if (IS_ERR(file)) {
+ iput(inode);
+ kfree(data);
+ return ERR_CAST(file);
+ }
+
+ file->f_flags |= O_LARGEFILE;
+
+ mapping = memfd->f_mapping;
+ mapping_set_unevictable(mapping);
+ mapping_set_gfp_mask(mapping,
+ mapping_gfp_mask(mapping) & ~__GFP_MOVABLE);
Is this supposed to prevent migration of pages being used for
restrictedmem/shmem backend?
Yes, my bad. I expected it to prevent migration, but it is not true.
Maybe add a comment that these pages are not movable and we don't want
to place them into movable pageblocks (including CMA and ZONE_MOVABLE).
That's the primary purpose of the GFP mask here.
--
Thanks,
David / dhildenb
