Merge tag 'sched_ext-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext updates from Tejun Heo:

 - Improve recovery from misbehaving BPF schedulers.

   When a scheduler puts many tasks with varying affinity restrictions
   on a shared DSQ, CPUs scanning through tasks they cannot run can
   overwhelm the system, causing lockups.

   Bypass mode now uses per-CPU DSQs with a load balancer to avoid this,
   and hooks into the hardlockup detector to attempt recovery.

   Add scx_cpu0 example scheduler to demonstrate this scenario.

 - Add lockless peek operation for DSQs to reduce lock contention for
   schedulers that need to query queue state during load balancing.

 - Allow scx_bpf_reenqueue_local() to be called from anywhere in
   preparation for deprecating cpu_acquire/release() callbacks in favor
   of generic BPF hooks.

 - Prepare for hierarchical scheduler support: add
   scx_bpf_task_set_slice() and scx_bpf_task_set_dsq_vtime() kfuncs,
   make scx_bpf_dsq_insert*() return bool, and wrap kfunc args in
   structs for future aux__prog parameter.

 - Implement cgroup_set_idle() callback to notify BPF schedulers when a
   cgroup's idle state changes.

 - Fix migration tasks being incorrectly downgraded from
   stop_sched_class to rt_sched_class across sched_ext enable/disable.
   Applied late as the fix is low risk and the bug subtle but needs
   stable backporting.

 - Various fixes and cleanups including cgroup exit ordering,
   SCX_KICK_WAIT reliability, and backward compatibility improvements.

* tag 'sched_ext-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (44 commits)
  sched_ext: Fix incorrect sched_class settings for per-cpu migration tasks
  sched_ext: tools: Removing duplicate targets during non-cross compilation
  sched_ext: Use kvfree_rcu() to release per-cpu ksyncs object
  sched_ext: Pass locked CPU parameter to scx_hardlockup() and add docs
  sched_ext: Update comments replacing breather with aborting mechanism
  sched_ext: Implement load balancer for bypass mode
  sched_ext: Factor out abbreviated dispatch dequeue into dispatch_dequeue_locked()
  sched_ext: Factor out scx_dsq_list_node cursor initialization into INIT_DSQ_LIST_CURSOR
  sched_ext: Add scx_cpu0 example scheduler
  sched_ext: Hook up hardlockup detector
  sched_ext: Make handle_lockup() propagate scx_verror() result
  sched_ext: Refactor lockup handlers into handle_lockup()
  sched_ext: Make scx_exit() and scx_vexit() return bool
  sched_ext: Exit dispatch and move operations immediately when aborting
  sched_ext: Simplify breather mechanism with scx_aborting flag
  sched_ext: Use per-CPU DSQs instead of per-node global DSQs in bypass mode
  sched_ext: Refactor do_enqueue_task() local and global DSQ paths
  sched_ext: Use shorter slice in bypass mode
  sched_ext: Mark racy bitfields to prevent adding fields that can't tolerate races
  sched_ext: Minor cleanups to scx_task_iter
  ...

1 files changed, 39 insertions, 0 deletions

diff --git a/include/trace/events/sched_ext.h b/include/trace/events/sched_ext.h
index 50e4b712735a..d1bf5acd59c5 100644
--- a/include/trace/events/sched_ext.h
+++ b/include/trace/events/sched_ext.h
@@ -45,6 +45,45 @@ TRACE_EVENT(sched_ext_event,
 	)
 );
 
+TRACE_EVENT(sched_ext_bypass_lb,
+
+	TP_PROTO(__u32 node, __u32 nr_cpus, __u32 nr_tasks, __u32 nr_balanced,
+		 __u32 before_min, __u32 before_max,
+		 __u32 after_min, __u32 after_max),
+
+	TP_ARGS(node, nr_cpus, nr_tasks, nr_balanced,
+		before_min, before_max, after_min, after_max),
+
+	TP_STRUCT__entry(
+		__field(	__u32,		node		)
+		__field(	__u32,		nr_cpus		)
+		__field(	__u32,		nr_tasks	)
+		__field(	__u32,		nr_balanced	)
+		__field(	__u32,		before_min	)
+		__field(	__u32,		before_max	)
+		__field(	__u32,		after_min	)
+		__field(	__u32,		after_max	)
+	),
+
+	TP_fast_assign(
+		__entry->node		= node;
+		__entry->nr_cpus	= nr_cpus;
+		__entry->nr_tasks	= nr_tasks;
+		__entry->nr_balanced	= nr_balanced;
+		__entry->before_min	= before_min;
+		__entry->before_max	= before_max;
+		__entry->after_min	= after_min;
+		__entry->after_max	= after_max;
+	),
+
+	TP_printk("node %u: nr_cpus=%u nr_tasks=%u nr_balanced=%u min=%u->%u max=%u->%u",
+		  __entry->node, __entry->nr_cpus,
+		  __entry->nr_tasks, __entry->nr_balanced,
+		  __entry->before_min, __entry->after_min,
+		  __entry->before_max, __entry->after_max
+	)
+);
+
 #endif /* _TRACE_SCHED_EXT_H */
 
 /* This part must be outside protection */