Messages in this thread | | | Date | Tue, 29 Nov 2022 14:21:39 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH v9 1/8] mm: Introduce memfd_restricted system call to create restricted user memory |
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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@linux.intel.com> > > > > <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.
Looks like we need to bump refcount in restrictedmem_get_page() and reduce it back when KVM is no longer use it.
Chao, could you adjust it?
-- Kiryl Shutsemau / Kirill A. Shutemov
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