linux-kernel - Re: WARNING: at drivers/gpu/drm/drm_crtc.c:82 drm_warn_on_modeset_not_all

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Message-ID: <CAPM=9tw-Ssu7ZYBZX7ipGt9w7zYG91tKbWZguM5DLPaqTakJPA@mail.gmail.com>
Date:	Thu, 2 May 2013 10:57:27 +1000
From:	Dave Airlie <airlied@...il.com>
To:	Daniel Vetter <daniel@...ll.ch>
Cc:	Borislav Petkov <bp@...en8.de>,
	lkml <linux-kernel@...r.kernel.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: WARNING: at drivers/gpu/drm/drm_crtc.c:82 drm_warn_on_modeset_not_all_locked+0x8d/0xc0()

On Thu, May 2, 2013 at 10:41 AM, Daniel Vetter <daniel@...ll.ch> wrote:
> On Thu, May 2, 2013 at 2:02 AM, Borislav Petkov <bp@...en8.de> wrote:
>> Hi,
>>
>> I'm seeing this when booting latest Linus tree + tip/master in kvm.
>> Config is attached. Looks like it cannot find root fs and panics and
>> calls the panic notifier which screams in drm_crtc.c because not all
>> modeset locks are taken. Maybe bogus?
>
> Locking in the drm panic notifiere is completely bogus (as in simply
> does not exist). The only difference is that with the new locking
> scheme in 3.9 we're now pretty obnixious about checking for these
> kinds of things. Also, drm drivers love to sleep in the panic
> handlers, too. It's somewhere on my giant list of things to fix in drm
> land, but I'm not sure whether I'll get around to it in this life or
> the next. Maybe we just need to shut up the WARN in case of a panic
> ...

Maybe? of course you do.

its a panic, getting anything on the screen is vastly more important than
the locking being perfect, any chance of any info landing on the screen
is being decreased by this spew.

Dave.
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