Re: [RFC PATCH 1/6] mm: Add F_SEAL_GUEST to shmem/memfd

[Kirill A. Shutemov]

On Thu, Nov 11, 2021 at 10:13:40PM +0800, Chao Peng wrote:
> The new seal is only allowed if there's no pre-existing pages in the fd
> and there's no existing mapping of the file. After the seal is set, no
> read/write/mmap from userspace is allowed.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
> Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>

Below is replacement patch with fallocate callback support.

I also replaced page_level if order of the page because PG_LEVEL_2M/4K is
x86-specific can cannot be used in the generic code.

There's also bugix in guest_invalidate_page().