From: Valentin Schneider <valentin.schneider@arm.com>
To: Dexuan Cui <decui@microsoft.com>
Cc: "mingo\@redhat.com" <mingo@redhat.com>,
"peterz\@infradead.org" <peterz@infradead.org>,
"juri.lelli\@redhat.com" <juri.lelli@redhat.com>,
"vincent.guittot\@linaro.org" <vincent.guittot@linaro.org>,
"dietmar.eggemann\@arm.com" <dietmar.eggemann@arm.com>,
"rostedt\@goodmis.org" <rostedt@goodmis.org>,
"bsegall\@google.com" <bsegall@google.com>,
"mgorman\@suse.de" <mgorman@suse.de>,
"bristot\@redhat.com" <bristot@redhat.com>,
"x86\@kernel.org" <x86@kernel.org>,
"linux-pm\@vger.kernel.org" <linux-pm@vger.kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hyperv\@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
Michael Kelley <mikelley@microsoft.com>
Subject: Re: v5.10: sched_cpu_dying() hits BUG_ON during hibernation: kernel BUG at kernel/sched/core.c:7596!
Date: Tue, 22 Dec 2020 13:39:53 +0000 [thread overview]
Message-ID: <jhjlfdqrmc6.mognet@arm.com> (raw)
In-Reply-To: <MW4PR21MB1857BF96E59E75EF9CE406E2BFDF9@MW4PR21MB1857.namprd21.prod.outlook.com>
Hi,
On 22/12/20 09:13, Dexuan Cui wrote:
> Hi,
> I'm running a Linux VM with the recent mainline (48342fc07272, 12/20/2020) on Hyper-V.
> When I test hibernation, the VM can easily hit the below BUG_ON during the resume
> procedure (I estimate this can repro about 1/5 of the time). BTW, my VM has 40 vCPUs.
>
> I can't repro the BUG_ON with v5.9.0, so I suspect something in v5.10.0 may be broken?
>
> In v5.10.0, when the BUG_ON happens, rq->nr_running==2, and rq->nr_pinned==0:
>
> 7587 int sched_cpu_dying(unsigned int cpu)
> 7588 {
> 7589 struct rq *rq = cpu_rq(cpu);
> 7590 struct rq_flags rf;
> 7591
> 7592 /* Handle pending wakeups and then migrate everything off */
> 7593 sched_tick_stop(cpu);
> 7594
> 7595 rq_lock_irqsave(rq, &rf);
> 7596 BUG_ON(rq->nr_running != 1 || rq_has_pinned_tasks(rq));
> 7597 rq_unlock_irqrestore(rq, &rf);
> 7598
> 7599 calc_load_migrate(rq);
> 7600 update_max_interval();
> 7601 nohz_balance_exit_idle(rq);
> 7602 hrtick_clear(rq);
> 7603 return 0;
> 7604 }
>
> The last commit that touches the BUG_ON line is the commit
> 3015ef4b98f5 ("sched/core: Make migrate disable and CPU hotplug cooperative")
> but the commit looks good to me.
>
> Any idea?
>
I'd wager this extra task is a kworker; could you give this series a try?
https://lore.kernel.org/r/20201218170919.2950-1-jiangshanlai@gmail.com
> Thanks,
> -- Dexuan
next prev parent reply other threads:[~2020-12-22 13:40 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-22 9:13 v5.10: sched_cpu_dying() hits BUG_ON during hibernation: kernel BUG at kernel/sched/core.c:7596! Dexuan Cui
2020-12-22 13:39 ` Valentin Schneider [this message]
2020-12-22 21:44 ` Dexuan Cui
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