From: Greg KH <gregkh@linuxfoundation.org>
To: qiang.zhang@windriver.com
Cc: stern@rowland.harvard.edu, dvyukov@google.com,
paulmck@kernel.org, dpenkler@gmail.com,
guido.kiener@rohde-schwarz.com, linux-usb@vger.kernel.org
Subject: Re: [PATCH] USB: usbtmc: Fix RCU stall warning
Date: Wed, 21 Jul 2021 09:08:50 +0200 [thread overview]
Message-ID: <YPfIAolSC8mJoQUr@kroah.com> (raw)
In-Reply-To: <20210629033236.7107-1-qiang.zhang@windriver.com>
On Tue, Jun 29, 2021 at 11:32:36AM +0800, qiang.zhang@windriver.com wrote:
> From: Zqiang <qiang.zhang@windriver.com>
I need a "full" name here, and in the signed-off-by line please.
>
> rcu: INFO: rcu_preempt self-detected stall on CPU
> rcu: 1-...!: (2 ticks this GP) idle=d92/1/0x4000000000000000
> softirq=25390/25392 fqs=3
> (t=12164 jiffies g=31645 q=43226)
> rcu: rcu_preempt kthread starved for 12162 jiffies! g31645 f0x0
> RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
> rcu: Unless rcu_preempt kthread gets sufficient CPU time,
> OOM is now expected behavior.
> rcu: RCU grace-period kthread stack dump:
> task:rcu_preempt state:R running task
>
> In the case of system use dummy_hcd as usb controller, when the
> usbtmc devices is disconnected, in usbtmc_interrupt(), if the urb
> status is unknown, the urb will be resubmit, the urb may be insert
> to dum_hcd->urbp_list again, this will cause the dummy_timer() not
> to exit for a long time, beacause the dummy_timer() be called in
> softirq and local_bh is disable, this not only causes the RCU reading
> critical area to consume too much time but also makes the tasks in
> the current CPU runq not run in time, and that triggered RCU stall.
>
> return directly when find the urb status is not zero to fix it.
>
> Reported-by: syzbot+e2eae5639e7203360018@syzkaller.appspotmail.com
> Signed-off-by: Zqiang <qiang.zhang@windriver.com>
What commit does this fix? Does it need to go to stable kernels?
What about the usbtmc maintainers, what do they think about this?
thanks,
greg k-h
next prev parent reply other threads:[~2021-07-21 7:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-29 3:32 [PATCH] USB: usbtmc: Fix RCU stall warning qiang.zhang
2021-07-07 1:29 ` Zhang, Qiang
2021-07-07 5:58 ` gregkh
2021-07-21 7:08 ` Greg KH [this message]
2021-07-21 7:30 ` Zhang, Qiang
2021-07-21 7:52 ` Greg KH
2021-07-21 8:28 ` Zhang, Qiang
2021-07-21 7:41 ` dave penkler
2021-07-21 7:52 ` Greg KH
2021-07-21 9:44 ` dave penkler
2021-07-21 9:47 ` Greg KH
2021-07-21 14:22 ` Alan Stern
2021-07-21 8:34 ` Zhang, Qiang
2021-07-21 11:15 Guido Kiener
2021-07-21 15:24 Guido Kiener
2021-07-21 16:17 ` Alan Stern
2021-07-21 17:08 Guido Kiener
2021-07-21 18:16 ` Alan Stern
2021-07-22 17:33 Guido Kiener
2021-07-23 0:36 ` Zhang, Qiang
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