From: Li Nan <linan122@xxxxxxxxxx> In iocg_pay_debt(), warn is triggered if 'active_list' is empty, which is intended to confirm iocg is avitve when it has debt. However, warn can be triggered during removing cgroup controller, as iocg_waitq_timer_fn() is awakened at that time. WARNING: CPU: 0 PID: 2344971 at block/blk-iocost.c:1402 iocg_pay_debt+0x14c/0x190 Call trace: iocg_pay_debt+0x14c/0x190 iocg_kick_waitq+0x438/0x4c0 iocg_waitq_timer_fn+0xd8/0x130 __run_hrtimer+0x144/0x45c __hrtimer_run_queues+0x16c/0x244 hrtimer_interrupt+0x2cc/0x7b0 The warn in this situation is meaningless. Since this iocg is being removed, the state of the 'active_list' is irrelevant, and 'waitq_timer' is canceled after removing 'active_list' in ioc_pd_free(), which ensure iocg is freed after iocg_waitq_timer_fn() returns. Therefore, add the check if iocg has already offlined to avoid warn when removing cgroup controller. Signed-off-by: Li Nan <linan122@xxxxxxxxxx> --- block/blk-iocost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index baa20c85799d..2e109c016a39 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1440,7 +1440,7 @@ static void iocg_pay_debt(struct ioc_gq *iocg, u64 abs_vpay, lockdep_assert_held(&iocg->waitq.lock); /* make sure that nobody messed with @iocg */ - WARN_ON_ONCE(list_empty(&iocg->active_list)); + WARN_ON_ONCE(list_empty(&iocg->active_list) && iocg->pd.online); WARN_ON_ONCE(iocg->inuse > 1); iocg->abs_vdebt -= min(abs_vpay, iocg->abs_vdebt); -- 2.39.2
