Re: 5.11 new lockdep warning related to led-class code (also may involve ata / piix controller)

From: Pavel Machek
Date: Tue Jan 12 2021 - 17:31:20 EST


Hi!

> Booting a 5.11-rc2 kernel with lockdep enabled inside a virtualbox vm (which still
> emulates good old piix ATA controllers) I get the below lockdep splat early on during boot:
>
> This seems to be led-class related but also seems to have a (P)ATA
> part to it. To the best of my knowledge this is a new problem in
> 5.11 .

This is on my for-next branch:

commit 9a5ad5c5b2d25508996f10ee6b428d5df91d9160 (HEAD -> for-next, origin/for-next)

leds: trigger: fix potential deadlock with libata

We have the following potential deadlock condition:

========================================================
WARNING: possible irq lock inversion dependency detected
5.10.0-rc2+ #25 Not tainted
--------------------------------------------------------
swapper/3/0 just changed the state of lock:
ffff8880063bd618 (&host->lock){-...}-{2:2}, at: ata_bmdma_interrupt+0x27/0x200
but this lock took another, HARDIRQ-READ-unsafe lock in the past:
(&trig->leddev_list_lock){.+.?}-{2:2}

If I'm not mistaken, that should fix your issue.

Best regards,

Pavel
--
http://www.livejournal.com/~pavelmachek

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