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

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Date:   Wed, 27 Jan 2021 23:01:34 +0100
From:   Pavel Machek <pavel@....cz>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, Dan Murphy <dmurphy@...com>,
        linux-ide@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: 5.11 new lockdep warning related to led-class code (also may
 involve ata / piix controller)

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.
> > 
> > I can confirm that this fixes things, thanks.
> > 
> > I assume that this will be part of some future 5.11 fixes pull-req?
> 
> This *regression* fix seems to still have not landed in 5.11-rc5, can
> we please get this on its way to Linus ?

Is it a regression? AFAIK it is a bug that has been there
forever... My original plan was to simply wait for 5.12, so it gets
full release of testing...

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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