Re: [PATCH] userns: enable tmpfs support for user namespace.

[ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman)]

Gao feng <gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> writes:

> mounting tmpfs in user namespace does no harm to the host.
> so enable tmpfs support for the user namespace.

I think this allows escaping from memory resource limits.

Eric

> Signed-off-by: Gao feng <gaofeng-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> ---
>  mm/shmem.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index d4e184e..ef97dc3 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2801,6 +2801,7 @@ static struct file_system_type shmem_fs_type = {
>  	.name		= "tmpfs",
>  	.mount		= shmem_mount,
>  	.kill_sb	= kill_litter_super,
> +	.fs_flags	= FS_USERNS_MOUNT,
>  };
>  
>  int __init shmem_init(void)