[CRIU] [PATCH 2/2] criu: don't trigger a bug if a task wants to restore a root mntns

[Pavel Emelyanov]

On 11/27/2015 04:00 PM, Andrey Vagin wrote:
> From: Andrew Vagin <avagin at virtuozzo.com>
> 
> It's possiable, if a parent task lives in a sub-mntns and
> its child lives in the root mntns. A mount namespace is
> restored before forking children, so all children are created
> in parent's mount namespace. If a child lives in another
> mount namespace, we need to move it into the required mntns.
> 
> Reported-by: Mr Jenkins
> Signed-off-by: Andrew Vagin <avagin at virtuozzo.com>
> ---
>  mount.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/mount.c b/mount.c
> index 6ad8058..afb5986 100644
> --- a/mount.c
> +++ b/mount.c
> @@ -2637,7 +2637,7 @@ int restore_task_mnt_ns(struct pstree_item *current)
>  			return -1;
>  		}
>  
> -		BUG_ON(nsid->type != NS_OTHER);
> +		BUG_ON(nsid->type == NS_CRIU);
>  
>  		if (do_restore_task_mnt_ns(nsid, current))
>  			return -1;
> @@ -2656,8 +2656,6 @@ void fini_restore_mntns(void)
>  	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next) {
>  		if (nsid->nd != &mnt_ns_desc)
>  			continue;
> -		if (root_item->ids->mnt_ns_id == nsid->id)
> -			continue;

How about skipping NS_CRIU namespace? Is it on the list?

>  		close(nsid->mnt.ns_fd);
>  	}
>  }
> @@ -2856,8 +2854,13 @@ int prepare_mnt_ns(void)
>  
>  		if (nsid->nd != &mnt_ns_desc)
>  			continue;
> -		if (root_item->ids->mnt_ns_id == nsid->id)
> +		if (root_item->ids->mnt_ns_id == nsid->id) {

Maybe fix this check to be nsid->type == NS_ROOT?

> +			/* Pin one with a file descriptor */
> +			nsid->mnt.ns_fd = open_proc(PROC_SELF, "ns/mnt");
> +			if (nsid->mnt.ns_fd < 0)
> +				goto err;
>  			continue;
> +		}
>  
>  		/* Create the new mount namespace */
>  		if (unshare(CLONE_NEWNS)) {
>