On Mon, Apr 1, 2019 at 4:41 AM Aleksa Sarai <cyphar@xxxxxxxxxx> wrote: > > Eric pitched a procfs2 which would *just* be the PIDs some time ago (in > an attempt to make it possible one day to mount /proc inside a container > without adding a bunch of masked paths), though it was just an idea and > I don't know if he ever had a patch for it. I wonder if we really want a fill procfs2, or maybe we could just make the pidfd readable (yes, it's a directory file descriptor, but we could allow reading). What are the *actual* use cases for opening /proc files through it? If it's really just for a small subset that android wants to do this (getting basic process state like "running" etc), rather than anything else, then we could skip the whole /proc linking entirely and go the other way instead (ie open_pidfd() would get that limited IO model, and we could make the /proc directory node get the same limited IO model). Linus