tree f807e9c0bd586d45971774ebf3108b48d0d46533
parent 0af7d783ce4939e21a41b4b9b686f07abde25e9d
author Li Zefan <lizefan@huawei.com> 1361168015 +0800
committer chrmhoffmann <chrmhoffmann@gmail.com> 1586074732 +0200

cgroup: fail if monitored file and event_control are in different cgroup

commit f169007b2773f285e098cb84c74aac0154d65ff7 upstream.

If we pass fd of memory.usage_in_bytes of cgroup A to cgroup.event_control
of cgroup B, then we won't get memory usage notification from A but B!

What's worse, if A and B are in different mount hierarchy, we'll end up
accessing NULL pointer!

Disallow this kind of invalid usage.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Weng Meiling <wengmeiling.weng@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>