linux-kernel - Re: BUG: sleeping function called from invalid context at kernel/locking/mutex.c db410c

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Date:   Wed, 22 Jul 2020 08:25:32 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     paulmck@...nel.org
Cc:     Arnd Bergmann <arnd@...db.de>,
        Naresh Kamboju <naresh.kamboju@...aro.org>,
        open list <linux-kernel@...r.kernel.org>, rcu@...r.kernel.org,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        lkft-triage@...ts.linaro.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        walter-zh.wu@...iatek.com, neeraju@...eaurora.org,
        Vinod Koul <vinod.koul@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: BUG: sleeping function called from invalid context at
 kernel/locking/mutex.c db410c

On Wed, Jul 22, 2020 at 6:01 AM Paul E. McKenney <paulmck@...nel.org> wrote:
>
> On Wed, Jul 22, 2020 at 10:04:21AM +0200, Arnd Bergmann wrote:
> > On Wed, Jul 22, 2020 at 9:44 AM Naresh Kamboju
> > <naresh.kamboju@...aro.org> wrote:
> > >
> > > Kernel BUG noticed on arm64 db410c device while booting linux next 20200721 tag.
> > > Continually popping up these BUG messages on the boot console and kernel warning
> > > also noticed.
> > >
> > > metadata:
> > >   git branch: master
> > >   git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
> > >   git commit: de2e69cfe54a8f2ed4b75f09d3110c514f45d38e
> > >   git describe: next-20200721
> > >   kernel-config:
> > > http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/dragonboard-410c/lkft/linux-next/818/config
> > >   build-location:
> > > http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/dragonboard-410c/lkft/linux-next/818
> > >
> > > Crash log:
> > > [    0.444349] BUG: sleeping function called from invalid context at
> > > /usr/src/kernel/kernel/locking/mutex.c:935
> > > [    0.444422] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid:
> > > 30, name: kworker/0:1
> > > [    0.444458] 2 locks held by kworker/0:1/30:
> > > [    0.444489]  #0: ffff00000eb15138
> > > ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x208/0x768
> > > [    0.444627]  #1: ffff800013713df0
> > > ((work_completion)(&sdp->work)){+.+.}-{0:0}, at:
> > > process_one_work+0x208/0x768
> > > [    0.444761] CPU: 0 PID: 30 Comm: kworker/0:1 Not tainted
> > > 5.8.0-rc6-next-20200721 #1
> > > [    0.444787] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
> > > [    0.444817] Workqueue: rcu_gp srcu_invoke_callbacks
> > > [    0.444856] Call trace:
> > > [    0.444883]  dump_backtrace+0x0/0x1f8
> > > [    0.444910]  show_stack+0x2c/0x38
> > > [    0.444939]  dump_stack+0xf0/0x16c
> > > [    0.444969]  ___might_sleep+0x144/0x208
> > > [    0.444996]  __might_sleep+0x54/0x90
> > > [    0.445027]  __mutex_lock+0x64/0x970
> > > [    0.445055]  mutex_lock_nested+0x54/0x70
> > > [    0.445084]  device_del+0x44/0x3c0
> > > [    0.445110]  device_unregister+0x24/0x78
> > > [    0.445138]  __device_link_free_srcu+0x64/0x70
> > > [    0.445164]  srcu_invoke_callbacks+0x10c/0x1a0
> >
> > The device_unregister() was added to __device_link_free_srcu() as part
> > of commit 287905e68dd2 ("driver core: Expose device link details in sysfs")
> >
> > I'm fairly sure this is what introduced the console output, though the
> > code before it is already suspicious:
> >
> > call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);
> >
> > According to the documentation, call_srcu() must not call any sleeping
> > functions, which is what the 'in_atomic(): 1' above is about.
>
> Yes, the callback function, in this case __device_link_free_srcu(),
> will execute from softirq context.
>
> > However, from what I can tell, the put_device() and pm_runtime_put()
> > calls in device_link_free() can also potentially sleep even if they normally
> > don't warn about that.
>
> The usual workaround is to have __device_link_free_srcu() schedule a
> workqueue that invokes the potentially sleeping functions.
>
>                                                         Thanx, Paul

Thanks for reporting. It was already reported and fixed last week.
Waiting on Greg to pull it in.
https://lore.kernel.org/lkml/CAGETcx9quqtV9TeD8WEcLLijGeV+7hXqnyiMv7F8xo+vyF_7iw@mail.gmail.com/#t


-Saravana