[GIT PULL for v7.1] kernel misc

[Christian Brauner]

Hey Linus,

/* Summary */

Features

- pid_namespace: make init creation more flexible

  Annotate ->child_reaper accesses with {READ,WRITE}_ONCE() to protect
  the unlocked readers from cpu/compiler reordering, and enforce that
  pid 1 in a pid namespace is always the first allocated pid (the
  set_tid path already required this).

  On top of that, allow opening pid_for_children before the pid
  namespace init has been created. This lets one process create the
  pid namespace and a different process create the init via setns(),
  which makes clone3(set_tid) usable in all cases evenly and is
  particularly useful to CRIU when restoring nested containers.

  A new selftest covers both the basic create-pidns-then-init flow and
  the cross-process variant, and a MAINTAINERS entry for the pid
  namespace code is added.

Cleanups

- signal: update outdated comment for the removed freezable_schedule()

/* Testing */

gcc (Debian 14.2.0-19) 14.2.0
Debian clang version 19.1.7 (3+b1)

No build failures or warnings were observed.

/* Conflicts */

Merge conflicts with mainline
=============================

No known conflicts.

Merge conflicts with other trees
================================

No known conflicts.

The following changes since commit 1f318b96cc84d7c2ab792fcc0bfd42a7ca890681:

  Linux 7.0-rc3 (2026-03-08 16:56:54 -0700)

are available in the Git repository at:

  git@xxxxxxxxxxxxxxxxxxx:pub/scm/linux/kernel/git/vfs/vfs tags/kernel-7.1-rc1.misc

for you to fetch changes up to 4c68d150246d7e1d826a807a82e6eb6b4669f42c:

  signal: update outdated comment for removed freezable_schedule() (2026-03-23 16:38:31 +0100)

----------------------------------------------------------------
kernel-7.1-rc1.misc

Please consider pulling these changes from the signed kernel-7.1-rc1.misc tag.

Thanks!
Christian

----------------------------------------------------------------
Christian Brauner (1):
      Merge patch series "pid_namespace: make init creation more flexible"

Kexin Sun (1):
      signal: update outdated comment for removed freezable_schedule()

Pavel Tikhomirov (5):
      pid_namespace: avoid optimization of accesses to ->child_reaper
      pid: check init is created first after idr alloc
      pid_namespace: allow opening pid_for_children before init was created
      selftests: Add tests for creating pidns init via setns
      MAINTAINERS: add a pid namespace entry

 MAINTAINERS                                        |  11 +-
 kernel/exit.c                                      |   3 +-
 kernel/fork.c                                      |   5 +-
 kernel/pid.c                                       |  19 +-
 kernel/pid_namespace.c                             |   9 -
 kernel/signal.c                                    |   5 +-
 tools/testing/selftests/pid_namespace/.gitignore   |   1 +
 tools/testing/selftests/pid_namespace/Makefile     |   2 +-
 .../selftests/pid_namespace/pidns_init_via_setns.c | 238 +++++++++++++++++++++
 9 files changed, 269 insertions(+), 24 deletions(-)
 create mode 100644 tools/testing/selftests/pid_namespace/pidns_init_via_setns.c