Subject: Re: [RFC 0/3] bpf: Add d_path helper

From: Al Viro <[email-masked]>
Date: Mon, 6 Apr 2020 13:47:40 +0100

On Mon, Apr 06, 2020 at 11:09:18AM +0200, Jiri Olsa wrote:

> it could be called as bpf helper from any place we could put
> the trampoline probe on.. so most of the kernel functions
> (at entry or exit) .. we can make checks, like for context
> before we allow to call it

Hard NAK, then.  If you can insert its call at the entry to
e.g. umount_tree(), you will get deadlocks.  The same for e.g.
select_collect() (same effect on a different seqlock).