Messages in this thread | | | Date | Wed, 06 Oct 2021 07:52:25 -0300 | From | Fabio Estevam <> | Subject | Re: [PATCH v3] serial: imx: Suppress false positive sysrq lockdep warning |
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Hi Johan,
On 06/10/2021 05:10, Johan Hovold wrote:
> Ok, thanks for testing. The above is what I meant and it does fix the > false-positive lockdep splat which motivated > uart_unlock_and_check_sysrq() to be added in the first place. > > Looking closer at the splat you reported (which you've edited quite > heavily), it becomes apparent that you are now hitting a different > locking issue. And it's not a false positive this time. > > There a problem with the workqueue debugging code, which unless fixed > at > the source, would prevent any console driver from queueing work while > holding a lock also taken in their write paths. And > tty_flip_buffer_push() is just one example of many. > > I can easily reproduce the splat with another serial driver, and I've > also been able to trigger the actual deadlock. > > I've prepared a patch that takes care of the workqueue state dumping, > which I'll send as a reply to this mail. Would you mind giving it a > spin > with the imx driver as well?
Yes, after applying only your patch I no longer get the lockdep splat. I have replied with my Tested-by, thanks.
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