kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-11-10 20:48:12 +00:00
Code Issues Releases Packages Activity

Merge patch series "namespace: allow creating empty mount namespaces"

Browse source 
Christian Brauner <brauner@kernel.org> says:

Currently, creating a new mount namespace always copies the entire mount
tree from the caller's namespace.  For containers and sandboxes that
intend to build their mount table from scratch this is wasteful: they
inherit a potentially large mount tree only to immediately tear it down.

This series adds support for creating a mount namespace that contains
only a clone of the root mount, with none of the child mounts.  Two new
flags are introduced:

- CLONE_EMPTY_MNTNS (0x400000000) for clone3(), using the 64-bit flag
  space.
- UNSHARE_EMPTY_MNTNS (0x00100000) for unshare(), reusing the
  CLONE_PARENT_SETTID bit which has no meaning for unshare.

Both flags imply CLONE_NEWNS.  The resulting namespace contains a single
nullfs root mount with an immutable empty directory.  The intended
workflow is to then mount a real filesystem (e.g., tmpfs) over the root
and build the mount table from there.

* patches from https://patch.msgid.link/20260306-work-empty-mntns-consolidated-v1-0-6eb30529bbb0@kernel.org:
  selftests/filesystems: add clone3 tests for empty mount namespaces
  selftests/filesystems: add tests for empty mount namespaces
  namespace: allow creating empty mount namespaces

Link: https://patch.msgid.link/20260306-work-empty-mntns-consolidated-v1-0-6eb30529bbb0@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2026-03-11 23:01:17 +01:00
commit 4e9f7592b6
No known key found for this signature in database
GPG key ID: 91C61BC06578DCA2
12 changed files with 2052 additions and 38 deletions
Download patch file Download diff file Expand all files Collapse all files