On Mon, Nov 20, 2017 at 10:07 AM, Michael Kerrisk (man-pages) <mtk.manpages@xxxxxxxxx> wrote: > But, the problem is that the existing description is at best misleading: > > (2) parent ID: the ID of the parent mount (or of self for > the top of the mount tree). > > That implies that we'll find one line in the list where field 1 and > field 2 are the same. But we don't, because the mountns rootfs entry > is not shown in mountinfo. On top of that, the reader is left > confused, because when they look at mountinfo, they see one entry > where the parent-ID doesn't exist in the list. So, something more than > the current text is required. After digging around in the kernel > source and noticing that chroot() will also cause this scenario, and > taking into account your comments, I revised the text to: > > (2) parent ID: the ID of the parent mount (or of self for > the root of this mount namespace's mount tree). > > If the parent mount point lies outside the process's > root directory (see chroot(2)), the ID shown here > won't have a corresponding record in mountinfo whose > mount ID (field 1) matches this parent mount ID > (because mount points that lie outside the process's > root directory are not shown in mountinfo). As a spe‐ > cial case of this point, the process's root mount > point may have a parent mount (for the initramfs > filesystem) that lies outside the process's root > directory, and an entry for that mount point will not > appear in mountinfo. > > How does that seem? Perfect. Thanks, Miklos
