sched_ext: Drop spurious warning on kick during scheduler disable

kick_cpus_irq_workfn() warns when scx_kick_syncs is NULL, but this can
legitimately happen when a BPF timer or other kick source races with
free_kick_syncs() during scheduler disable. Drop the pr_warn_once() and
add a comment explaining the race.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index b8dbae251fd5887157abd69f7ac48967da032346..012ca8bd70fbdf75a04cd5b0cd012501a184790d 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -7600,10 +7600,9 @@ static void kick_cpus_irq_workfn(struct irq_work *irq_work)
        unsigned long *ksyncs;
        s32 cpu;
 
-       if (unlikely(!ksyncs_pcpu)) {
-               pr_warn_once("kick_cpus_irq_workfn() called with NULL scx_kick_syncs");
+       /* can race with free_kick_syncs() during scheduler disable */
+       if (unlikely(!ksyncs_pcpu))
                return;
-       }
 
        ksyncs = rcu_dereference_bh(ksyncs_pcpu)->syncs;