Messages in this thread | | | Date | Fri, 19 Apr 2024 17:20:20 +0800 | Subject | Re: [PATCH] blk-iocost: do not WARNING if iocg has already offlined | From | Li Nan <> |
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在 2024/4/19 0:14, Tejun Heo 写道: > Hello, > > On Thu, Apr 18, 2024 at 03:23:40PM +0800, linan666@huaweicloud.com wrote: >> From: Li Nan <linan122@huawei.com> >> >> 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 > > Maybe saying "a blkcg is being removed" is clearer?
Thanks for your suggestion. I will correct my expression in next version.
> >> 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@huawei.com> >> --- >> 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); > > Can you add a comment explaining why we need the pd.online test?
Yeah, I will add comment in next version.
> > Other than the above nits, looks great to me. Please feel free to add > > Acked-by: Tejun Heo <tj@kernel.org> > > Thanks. >
-- Thanks, Nan
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