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sched_ext: Fixes for v6.19-rc3

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- Fix uninitialized @ret on alloc_percpu() failure leading to ERR_PTR(0).
 
 - Fix PREEMPT_RT warning when bypass load balancer sends IPI to offline
   CPU by using resched_cpu() instead of resched_curr().
 
 - Fix comment referring to renamed function.
 
 - Update scx_show_state.py for scx_root and scx_aborting changes.
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Merge tag 'sched_ext-for-6.19-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fixes from Tejun Heo:

 - Fix uninitialized @ret on alloc_percpu() failure leading to
   ERR_PTR(0)

 - Fix PREEMPT_RT warning when bypass load balancer sends IPI to offline
   CPU by using resched_cpu() instead of resched_curr()

 - Fix comment referring to renamed function

 - Update scx_show_state.py for scx_root and scx_aborting changes

* tag 'sched_ext-for-6.19-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  tools/sched_ext: update scx_show_state.py for scx_aborting change
  tools/sched_ext: fix scx_show_state.py for scx_root change
  sched_ext: Use the resched_cpu() to replace resched_curr() in the bypass_lb_node()
  sched_ext: Fix some comments in ext.c
  sched_ext: fix uninitialized ret on alloc_percpu() failure
This commit is contained in:
Linus Torvalds 2025-12-28 17:21:36 -08:00
commit 7839932417
2 changed files with 16 additions and 17 deletions
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23
kernel/sched/ext.c
View File

@ -1577,7 +1577,7 @@ static bool dequeue_task_scx(struct rq *rq, struct task_struct *p, int deq_flags
*
* @p may go through multiple stopping <-> running transitions between
* here and put_prev_task_scx() if task attribute changes occur while
* balance_scx() leaves @rq unlocked. However, they don't contain any
* balance_one() leaves @rq unlocked. However, they don't contain any
* information meaningful to the BPF scheduler and can be suppressed by
* skipping the callbacks if the task is !QUEUED.
*/
@ -2372,7 +2372,7 @@ static void switch_class(struct rq *rq, struct task_struct *next)
* preempted, and it regaining control of the CPU.
*
* ->cpu_release() complements ->cpu_acquire(), which is emitted the
* next time that balance_scx() is invoked.
* next time that balance_one() is invoked.
*/
if (!rq->scx.cpu_released) {
if (SCX_HAS_OP(sch, cpu_release)) {
@ -2478,7 +2478,7 @@ do_pick_task_scx(struct rq *rq, struct rq_flags *rf, bool force_scx)
}
/*
* If balance_scx() is telling us to keep running @prev, replenish slice
* If balance_one() is telling us to keep running @prev, replenish slice
* if necessary and keep running @prev. Otherwise, pop the first one
* from the local DSQ.
*/
@ -3956,13 +3956,8 @@ static void bypass_lb_node(struct scx_sched *sch, int node)
nr_donor_target, nr_target);
}
for_each_cpu(cpu, resched_mask) {
struct rq *rq = cpu_rq(cpu);
raw_spin_rq_lock_irq(rq);
resched_curr(rq);
raw_spin_rq_unlock_irq(rq);
}
for_each_cpu(cpu, resched_mask)
resched_cpu(cpu);
for_each_cpu_and(cpu, cpu_online_mask, node_mask) {
u32 nr = READ_ONCE(cpu_rq(cpu)->scx.bypass_dsq.nr);
@ -4025,7 +4020,7 @@ static DEFINE_TIMER(scx_bypass_lb_timer, scx_bypass_lb_timerfn);
*
* - ops.dispatch() is ignored.
*
* - balance_scx() does not set %SCX_RQ_BAL_KEEP on non-zero slice as slice
* - balance_one() does not set %SCX_RQ_BAL_KEEP on non-zero slice as slice
* can't be trusted. Whenever a tick triggers, the running task is rotated to
* the tail of the queue with core_sched_at touched.
*
@ -4783,8 +4778,10 @@ static struct scx_sched *scx_alloc_and_add_sched(struct sched_ext_ops *ops)
}
sch->pcpu = alloc_percpu(struct scx_sched_pcpu);
if (!sch->pcpu)
if (!sch->pcpu) {
ret = -ENOMEM;
goto err_free_gdsqs;
}
sch->helper = kthread_run_worker(0, "sched_ext_helper");
if (IS_ERR(sch->helper)) {
@ -6067,7 +6064,7 @@ __bpf_kfunc bool scx_bpf_dsq_move_to_local(u64 dsq_id)
/*
* A successfully consumed task can be dequeued before it starts
* running while the CPU is trying to migrate other dispatched
* tasks. Bump nr_tasks to tell balance_scx() to retry on empty
* tasks. Bump nr_tasks to tell balance_one() to retry on empty
* local DSQ.
*/
dspc->nr_tasks++;

10
tools/sched_ext/scx_show_state.py
View File

@ -27,16 +27,18 @@ def read_static_key(name):
def state_str(state):
return prog['scx_enable_state_str'][state].string_().decode()
ops = prog['scx_ops']
root = prog['scx_root']
enable_state = read_atomic("scx_enable_state_var")
print(f'ops : {ops.name.string_().decode()}')
if root:
print(f'ops : {root.ops.name.string_().decode()}')
else:
print('ops : ')
print(f'enabled : {read_static_key("__scx_enabled")}')
print(f'switching_all : {read_int("scx_switching_all")}')
print(f'switched_all : {read_static_key("__scx_switched_all")}')
print(f'enable_state : {state_str(enable_state)} ({enable_state})')
print(f'in_softlockup : {prog["scx_in_softlockup"].value_()}')
print(f'breather_depth: {read_atomic("scx_breather_depth")}')
print(f'aborting : {prog["scx_aborting"].value_()}')
print(f'bypass_depth : {prog["scx_bypass_depth"].value_()}')
print(f'nr_rejected : {read_atomic("scx_nr_rejected")}')
print(f'enable_seq : {read_atomic("scx_enable_seq")}')