[GIT PULL] sched_ext: Fixes for v7.0-rc2

[Tejun Heo]

Hello,

The following changes since commit 640c9dc72f21f325700a4b0f839ad568ff21c697:

  tools/sched_ext: fix getopt not re-parsed on restart (2026-02-20 17:17:38 -1000)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git tags/sched_ext-for-7.0-rc2-fixes

for you to fetch changes up to b06ccbabe2506fd70b9167a644978b049150224a:

  sched_ext: Fix starvation of scx_enable() under fair-class saturation (2026-03-03 11:10:40 -1000)

Note: There's a merge conflict in kernel/sched/ext_idle.c between
189f164e573e ("Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL
uses") from the slab tree and 2a064262eb37 ("sched_ext: Fix
out-of-bounds access in scx_idle_init_masks()") from this pull. The
former converts kcalloc() to kzalloc_objs() and the latter changes
num_possible_nodes() to nr_node_ids. The resolution is to take both:

  /* before (master) */
  scx_idle_node_masks = kzalloc_objs(*scx_idle_node_masks,
                                     num_possible_nodes());

  /* after (resolved) */
  scx_idle_node_masks = kzalloc_objs(*scx_idle_node_masks,
                                     nr_node_ids);

A test-merge branch is available at:

  https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git test-merge-for-7.0-rc2-fixes

----------------------------------------------------------------
sched_ext: Fixes for v7.0-rc2

- Fix starvation of scx_enable() under fair-class saturation by
  offloading the enable path to an RT kthread.

- Fix out-of-bounds access in idle mask initialization on systems with
  non-contiguous NUMA node IDs.

- Fix a preemption window during scheduler exit and a refcount underflow
  in cgroup init error path.

- Fix SCX_EFLAG_INITIALIZED being a no-op flag.

- Add READ_ONCE() annotations for KCSAN-clean lockless accesses and
  replace naked scx_root dereferences with container_of() in kobject
  callbacks.

- Tooling and selftest fixes: compilation issues with clang 17,
  strtoul() misuse, unused options cleanup, and Kconfig sync.

----------------------------------------------------------------
Cheng-Yang Chou (8):
      selftests/sched_ext: Abort test loop on signal
      selftests/sched_ext: Fix unused-result warning for read()
      tools/sched_ext: scx_central: Remove unused '-p' option
      tools/sched_ext: scx_sdt: Remove unused '-f' option
      selftests/sched_ext: Remove duplicated unistd.h include in rt_stall.c
      tools/sched_ext: Sync README.md Kconfig with upstream scx
      tools/sched_ext: Add Kconfig to sync with upstream
      sched_ext: Remove redundant css_put() in scx_cgroup_init()

David Carlier (3):
      sched_ext: Fix out-of-bounds access in scx_idle_init_masks()
      sched_ext: Fix SCX_EFLAG_INITIALIZED being a no-op flag
      tools/sched_ext: fix strtoul() misuse in scx_hotplug_seq()

Tejun Heo (2):
      sched_ext: Disable preemption between scx_claim_exit() and kicking helper work
      sched_ext: Fix starvation of scx_enable() under fair-class saturation

Zhao Mengmeng (3):
      tools/sched_ext: Add -fms-extensions to bpf build flags
      selftests/sched_ext: Add -fms-extensions to bpf build flags
      selftests/sched_ext: Fix peek_dsq.bpf.c compile error for clang 17

zhidao su (3):
      sched_ext: Use READ_ONCE() for the read side of dsq->nr update
      sched_ext: Replace naked scx_root dereferences in kobject callbacks
      sched_ext: Use READ_ONCE() for plain reads of scx_watchdog_timeout

 kernel/sched/ext.c                                 | 101 +++++++++++++++++----
 kernel/sched/ext_idle.c                            |   4 +-
 kernel/sched/ext_internal.h                        |   2 +-
 tools/sched_ext/Kconfig                            |  61 +++++++++++++
 tools/sched_ext/Makefile                           |   2 +
 tools/sched_ext/README.md                          |   6 --
 tools/sched_ext/include/scx/compat.h               |   7 +-
 tools/sched_ext/scx_central.c                      |   2 +-
 tools/sched_ext/scx_sdt.c                          |   2 +-
 tools/testing/selftests/sched_ext/Makefile         |   2 +
 .../selftests/sched_ext/init_enable_count.c        |   3 +-
 tools/testing/selftests/sched_ext/peek_dsq.bpf.c   |   4 +-
 tools/testing/selftests/sched_ext/rt_stall.c       |   1 -
 tools/testing/selftests/sched_ext/runner.c         |   3 +
 14 files changed, 165 insertions(+), 35 deletions(-)
 create mode 100644 tools/sched_ext/Kconfig

Thanks.

--
tejun