Re: [PATCH 1/3] Save dump_root into pid_namespace

[Al Viro]

On Mon, Jun 06, 2016 at 08:02:08PM +0800, Zhao Lei wrote:
> +     spin_lock(&pid_ns->root_for_dump_lock);
> +
> +     if (pid_ns->root_for_dump.mnt)
> +             path_put(&pid_ns->root_for_dump);

NAK, for obvious reasons - don't do blocking operations under spinlocks,
for starters.