linux-kernel - Re: Sleeping in atomic context on device release due to device links

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Date:   Wed, 28 Apr 2021 10:27:46 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: Sleeping in atomic context on device release due to device links

On Mon, Apr 26, 2021 at 10:08 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> Hi!
>
> Is the below already fixed somewhere (v5.12 seems still has it)?
> Or I missed something?
>
> [  186.439095] BUG: sleeping function called from invalid context at
> drivers/gpio/gpiolib.c:1952
> [  186.451666] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid:
> 119, name: kworker/0:2
> [  186.463885] 2 locks held by kworker/0:2/119:
> [  186.470831]  #0: ffff985d8110d338
> ((wq_completion)rcu_gp){....}-{0:0}, at: process_one_work+0x1bc/0x4b0
> [  186.484458]  #1: ffffb1a2c0367e70
> ((work_completion)(&sdp->work)){....}-{0:0}, at:
> process_one_work+0x1bc/0x4b
> 0
> [  186.498732] CPU: 0 PID: 119 Comm: kworker/0:2 Not tainted 5.12.0-rc8+ #168
> [  186.508301] Hardware name: Intel Corporation Merrifield/BODEGA BAY,
> BIOS 542 2015.01.21:18.19.48
> [  186.521000] Workqueue: rcu_gp srcu_invoke_callbacks
> [  186.528515] Call Trace:
> [  186.532288]  dump_stack+0x69/0x8e
> [  186.536964]  ___might_sleep.cold+0x95/0xa2
> [  186.543606]  gpiod_free_commit+0x25/0x170
> [  186.550163]  gpiod_put+0x19/0x40
> [  186.554728]  cleanup+0x1b/0x30 [spi_pxa2xx_platform]
> [  186.562246]  spidev_release+0x24/0x50
> [  186.567243]  device_release+0x34/0x90
> [  186.572228]  kobject_put+0x86/0x1d0
> [  186.577035]  __device_link_free_srcu+0x47/0x70
> [  186.583942]  srcu_invoke_callbacks+0xc8/0x170

Hi Rafael,

So it looks like put_device() is not guaranteed to be atomic and
srcu_invoke_callbacks() runs in atomic context. I haven't dug into why
the SRCU implementation is needed for device links and what needs to
be in the srcu callback vs be done earlier in the actual caller
context.

Can you please look into this and give your thoughts?

-Saravana

> [  186.590720]  process_one_work+0x24d/0x4b0
> [  186.597118]  worker_thread+0x55/0x3c0
> [  186.602030]  ? rescuer_thread+0x390/0x390
> [  186.608373]  kthread+0x137/0x150
> [  186.612834]  ? __kthread_bind_mask+0x60/0x60
> [  186.619446]  ret_from_fork+0x22/0x30
>
>
> --
> With Best Regards,
> Andy Shevchenko