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.

SEE ALSO

       proc(5)