Merge tag 'sched_ext-for-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fixes from Tejun Heo:

 - Three build fixes

 - The fix for a stall bug introduced by a recent optimization in sched
   core (SM_IDLE)

 - Addition of /sys/kernel/sched_ext/enable_seq. While not a fix, it is
   a simple addition that distro people want to be able to tell whether
   an SCX scheduler has ever been loaded on the system

* tag 'sched_ext-for-6.12-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: Provide a sysfs enable_seq counter
  sched_ext: Fix build when !CONFIG_STACKTRACE
  sched, sched_ext: Disable SM_IDLE/rq empty path when scx_enabled()
  sched: Put task_group::idle under CONFIG_GROUP_SCHED_WEIGHT
  sched: Add dummy version of sched_group_set_idle()

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst
index a707d2181a77..6c0d70e2e27d 100644
--- a/Documentation/scheduler/sched-ext.rst
+++ b/Documentation/scheduler/sched-ext.rst
@@ -83,6 +83,15 @@ The current status of the BPF scheduler can be determined as follows:
     # cat /sys/kernel/sched_ext/root/ops
     simple
 
+You can check if any BPF scheduler has ever been loaded since boot by examining
+this monotonically incrementing counter (a value of zero indicates that no BPF
+scheduler has been loaded):
+
+.. code-block:: none
+
+    # cat /sys/kernel/sched_ext/enable_seq
+    1
+
 ``tools/sched_ext/scx_show_state.py`` is a drgn script which shows more
 detailed information:
 
@@ -96,6 +105,7 @@ detailed information:
     enable_state  : enabled (2)
     bypass_depth  : 0
     nr_rejected   : 0
+    enable_seq    : 1
 
 If ``CONFIG_SCHED_DEBUG`` is set, whether a given task is on sched_ext can
 be determined as follows: