Re: musb RPM sleep-while-atomic in 4.9-rc1

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> [161020 08:38]:
> Hi Tony,
> 
> I'm getting the splat below when booting 4.9-rc1 on a BBB and
> tracked it down to 65b3f50ed6fa ("usb: musb: Add PM runtime support for
> MUSB DSPS glue layer") which added a synchronous RPM get in a timer
> callback:

OK, sorry to hear about that. Care to email me your .config and how
to reproduce and what do you have connected like a hub? Also do
you use built-in gadgets or configure them via configfs?

> [    6.466226] BUG: sleeping function called from invalid context at /home/johan/work/omicron/src/linux/drivers/base/power/runtime.c:955
> [    6.478850] in_atomic(): 1, irqs_disabled(): 0, pid: 59, name: grep
> [    6.485434] 1 lock held by grep/59:
> [    6.489102]  #0: [    6.490966]  (
> ((&glue->timer))[    6.494206] ){+.-...}
> , at: [    6.497194] [<c0191084>] call_timer_fn+0x0/0x41c
> [    6.502048] Preemption disabled at:[    6.505540] [<c01015e0>] __do_softirq+0x80/0x594
> [    6.510393] 
> [    6.511974] CPU: 0 PID: 59 Comm: grep Not tainted 4.9.0-rc1 #46
> [    6.518190] Hardware name: Generic AM33XX (Flattened Device Tree)
> [    6.524613] [<c01116e4>] (unwind_backtrace) from [<c010dec0>] (show_stack+0x20/0x24)
> [    6.532753] [<c010dec0>] (show_stack) from [<c0364f1c>] (dump_stack+0x24/0x28)
> [    6.540351] [<c0364f1c>] (dump_stack) from [<c015ea58>] (___might_sleep+0x1d8/0x2c4)
> [    6.548486] [<c015ea58>] (___might_sleep) from [<c015ebb4>] (__might_sleep+0x70/0xa8)
> [    6.556720] [<c015ebb4>] (__might_sleep) from [<c0413d60>] (__pm_runtime_resume+0x9c/0xa0)
> [    6.565404] [<c0413d60>] (__pm_runtime_resume) from [<c04d0bc4>] (otg_timer+0x3c/0x254)
> [    6.573813] [<c04d0bc4>] (otg_timer) from [<c0191180>] (call_timer_fn+0xfc/0x41c)
> [    6.581675] [<c0191180>] (call_timer_fn) from [<c01915c0>] (expire_timers+0x120/0x210)
> [    6.589990] [<c01915c0>] (expire_timers) from [<c0191acc>] (run_timer_softirq+0xa4/0xdc)
> [    6.598487] [<c0191acc>] (run_timer_softirq) from [<c010168c>] (__do_softirq+0x12c/0x594)
> [    6.607079] [<c010168c>] (__do_softirq) from [<c01384cc>] (irq_exit+0xf4/0x130)
> [    6.614766] [<c01384cc>] (irq_exit) from [<c017d910>] (__handle_domain_irq+0x84/0xec)
> [    6.622991] [<c017d910>] (__handle_domain_irq) from [<c0101500>] (omap_intc_handle_irq+0x44/0xa0)
> [    6.632306] [<c0101500>] (omap_intc_handle_irq) from [<c010ee78>] (__irq_usr+0x58/0x80)
> [    6.640716] Exception stack(0xcf669fb0 to 0xcf669ff8)
> [    6.646028] 9fa0:                                     b6fd5050 0012ebb0 b6e71058 b6e1c088
> [    6.654614] 9fc0: b6e07000 00000001 b6e1cb10 b6fd5000 00000001 00000000 b6fd38e8 bec32a54
> [    6.663198] 9fe0: b6e1c870 bec32990 b6fb0a20 b6fb9758 20030010 ffffffff
> 
> Setting the irq_safe flag seems to do the trick, but not sure that's
> what you intended to do.

That's what we want to avoid as it keep the parent device permanently
enabled. To avoid that we want to just queue things and deal with them
from pm_runtime_resume.

> I saw you posted some regression fixes lately, but they did not look
> related to this at first glance at least.

Yeah this seems different. Can you still try v4.9-rc + patches from
thread "[PATCH 0/2] Fixes for two more musb regressions"?

Regards,

Tony
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