NAME¶
/proc/pid/mountinfo - mount information
DESCRIPTION¶
- /proc/pid/mountinfo (since Linux 2.6.26)
- This file contains information about mounts in the process's mount
namespace (see mount_namespaces(7)). It supplies various
information (e.g., propagation state, root of mount for bind mounts,
identifier for each mount and its parent) that is missing from the (older)
/proc/pid/mounts file, and fixes various other problems with
that file (e.g., nonextensibility, failure to distinguish per-mount versus
per-superblock options).
- The file contains lines of the form:
-
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
- The numbers in parentheses are labels for the descriptions below:
- (1)
- mount ID: a unique ID for the mount (may be reused after
umount(2)).
- (2)
- parent ID: the ID of the parent mount (or of self for the root of this
mount namespace's mount tree).
- If a new mount is stacked on top of a previous existing mount (so that it
hides the existing mount) at pathname P, then the parent of the new mount
is the previous mount at that location. Thus, when looking at all the
mounts stacked at a particular location, the top-most mount is the one
that is not the parent of any other mount at the same location. (Note,
however, that this top-most mount will be accessible only if the longest
path subprefix of P that is a mount point is not itself hidden by a
stacked mount.)
- If the parent mount 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 mounts that lie outside the process's root directory are not
shown in mountinfo). As a special case of this point, the process's
root mount may have a parent mount (for the initramfs filesystem) that
lies outside the process's root directory, and an entry for that mount
will not appear in mountinfo.
- (3)
- major:minor: the value of st_dev for files on this filesystem (see
stat(2)).
- (4)
- root: the pathname of the directory in the filesystem which forms the root
of this mount.
- (5)
- mount point: the pathname of the mount point relative to the process's
root directory.
- (6)
- mount options: per-mount options (see mount(2)).
- (7)
- optional fields: zero or more fields of the form "tag[:value]";
see below.
- (8)
- separator: the end of the optional fields is marked by a single
hyphen.
- (9)
- filesystem type: the filesystem type in the form
"type[.subtype]".
- (10)
- mount source: filesystem-specific information or "none".
- (11)
- super options: per-superblock options (see mount(2)).
- Currently, the possible optional fields are shared, master,
propagate_from, and unbindable. See
mount_namespaces(7) for a description of these fields. Parsers
should ignore all unrecognized optional fields.
- For more information on mount propagation see
Documentation/filesystems/sharedsubtree.rst (or
Documentation/filesystems/sharedsubtree.txt before Linux 5.8) in
the Linux kernel source tree.