Bug 90681

Summary: Radeon Kernel Oops & Lockup when switching on DisplayPort attached monitor
Product: DRI Reporter: Richard Bradfield <bradfirj>
Component: DRM/RadeonAssignee: Default DRI bug account <dri-devel>
Status: RESOLVED FIXED QA Contact:
Severity: major    
Priority: medium CC: kparal, samuel
Version: unspecified   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: i915 features:
Attachments:
Description Flags
journalctl output for crash
none
lspci -nn
none
Oops stack trace only
none
Bisection log
none
Culprit commit according to bisect
none
possible fix none

Description Richard Bradfield 2015-05-27 14:14:42 UTC 
Created attachment 116079 [details]
journalctl output for crash

Switching my DisplayPort attached monitor on (or off and then on again) while booted to multiuser target (no Xorg or Wayland) causes a kernel Oops, followed by soft-lockups which render the system unusable.

Doing the same while at the full Graphical target causes gnome-shell to crash, but it is possible to recover the system by logging in again.

The kernel error and IP are:
>May 24 23:25:28 fedora-workstation.home kernel: BUG: unable to handle kernel NULL pointer dereference at 00000000000003b0
>May 24 23:25:28 fedora-workstation.home kernel: IP: [<ffffffffa0152055>] radeon_connector_edid+0x5/0x70 [radeon]

Full journal from a reproduction of the bug will be attached, as will lspci -nn.

I have isolated this using git bisect to the following commit (the patch for which is attached to this bug).
This is a commit currently part of the linux-stable tree and lies between 4.0.2 and 4.0.3

>016a255b7835ee7e49a3eba3c14ba0bc0221a4f8 is the first bad commit
>commit 016a255b7835ee7e49a3eba3c14ba0bc0221a4f8
>Author: Alex Deucher <alexander.deucher@amd.com>
>Date:   Tue Apr 7 09:52:42 2015 -0400
>
>    drm/radeon: only mark audio as connected if the monitor supports it (v3)
>    
>    commit 0f55db36d49d45b80eff0c0a2a498766016f458b upstream.
>    
>    Otherwise the driver may try and send audio which may confuse the
>    monitor.
>    
>    v2: set pin to NULL if no audio
>    v3: avoid crash with analog encoders
>    
>    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>>
>
>:040000 040000 de0366a6790f5c91d175bcb89cb34956bbe72b26 >bbdb5734961f824558152c7c34a840c78bc3a9a9 M	drivers
Comment 1 Richard Bradfield 2015-05-27 14:15:10 UTC 
Created attachment 116080 [details]
lspci -nn
Comment 2 Richard Bradfield 2015-05-27 14:15:36 UTC 
Created attachment 116081 [details]
Oops stack trace only
Comment 3 Richard Bradfield 2015-05-27 14:16:15 UTC 
Created attachment 116082 [details]
Bisection log
Comment 4 Richard Bradfield 2015-05-27 14:17:00 UTC 
Created attachment 116083 [details] [review]
Culprit commit according to bisect

Sorry for the bug-spam, I wasn't sure how to add many attachments at once.
Comment 5 Alex Deucher 2015-05-27 15:37:40 UTC 
Created attachment 116085 [details] [review]
possible fix

Does the attached patch fix the issue?
Comment 6 Alex Deucher 2015-05-27 15:59:55 UTC 
Actually reverting the commit is probably the proper fix.
Comment 7 Richard Bradfield 2015-05-27 16:05:57 UTC 
Patch fixes the issue, I can try a revert as well.

With the patch applied, there's still a problem with gnome-shell crashing, but there's no Oops in the VT any more.
Comment 8 Richard Bradfield 2015-05-27 17:08:23 UTC 
(In reply to Alex Deucher from comment #6)
> Actually reverting the commit is probably the proper fix.

Reverting the commit doesn't fix the issue, there is still a kernel Oops upon hotplugging the monitor. I'll dig into the trace.
Comment 9 Alex Deucher 2015-05-27 17:14:28 UTC 
How about the revert and the patch?
Comment 10 Richard Bradfield 2015-05-27 18:02:42 UTC 
(In reply to Alex Deucher from comment #9)
> How about the revert and the patch?

Revert and patch is working for me.
Comment 11 Andreas Tunek 2015-07-20 17:58:03 UTC 
Is this fixed? I am asking because 91253 is probably due to the same committ.
Comment 13 Andreas Tunek 2015-07-21 19:37:03 UTC 
Will this be in 4.2 rc3?
Comment 14 Alex Deucher 2015-07-21 19:41:14 UTC 
(In reply to Andreas Tunek from comment #13)
> Will this be in 4.2 rc3?

Yes, they are in 4.1 as well.

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