On 2019/01/03 1:16, Tejun Heo wrote: > Happy new year, Tetsuo. > > On Wed, Jan 02, 2019 at 09:08:56PM +0900, Tetsuo Handa wrote: >> According to commit 633feee310de6b6c ("cgroup: refactor mount path and >> clearly distinguish v1 and v2 paths"), cgroup_do_mount() is failing to >> do full teardown steps for kernfs_mount() (deactivate_locked_super() ?) >> when kernfs_node_dentry() failed. > > Hmm... that's basically dget()'ing the root dentry of the sb. I'm not > sure how that could fail. Can it? kernfs_node_dentry() calls lookup_one_len_unlocked() which involves memory allocation, and memory allocation fault injection made lookup_one_len_unlocked() fail, and thus kernfs_node_dentry() failed. What's strange?