On Mon, Sep 28, 2020 at 12:11:30AM +0800, Chengming Zhou wrote: > The WARN_ON/WARN_ON_ONCE with rq lock held in __schedule() should be > deferred by marking the PRINTK_DEFERRED_CONTEXT_MASK, or will cause > deadlock on rq lock in the printk path.
It also shouldn't happen in the first place, so who bloody cares. > Signed-off-by: Chengming Zhou <zhouchengm...@bytedance.com> > Signed-off-by: Muchun Song <songmuc...@bytedance.com> > --- > kernel/sched/core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 2d95dc3f4644..81d8bf614225 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4444,6 +4444,7 @@ static void __sched notrace __schedule(bool preempt) > */ > rq_lock(rq, &rf); > smp_mb__after_spinlock(); > + printk_deferred_enter(); > > /* Promote REQ to ACT */ > rq->clock_update_flags <<= 1; > @@ -4530,6 +4531,7 @@ static void __sched notrace __schedule(bool preempt) > rq_unlock_irq(rq, &rf); > } > > + printk_deferred_exit(); > balance_callback(rq); > } NAK printk_deferred is an abomination, kill that.
