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

From: Pavel Machek
Date: Wed Jan 27 2021 - 17:04:51 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.
> >
> > 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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