kernel-packages team mailing list archive

[Sergio Callegari <sergio.callegari@xxxxxxxxx>]

To Jussi...

as the original reporter of this bug, I think it has no hope of being fixed even if you provide all the relevant kernel commits.
Which is bad, because the crash is serious and happens 'late' when may kernel data structures may have been written over, with potential data loss.

I tried to provide pointers to all the relevant LKML entries and the
only replies I got was that I should have run apport-collect, which was
a bit frustrating. I hope that your list, that is much more organized
than my posts, has a better success.

Besides that, the bad news is that even on trusty (that has kernel
3.14), bluetooth dun is broken. At least here the issue is mere lack of
functionality, no crashes. This is due to:

- another kernel bug (it is probably http://lists.openwall.net/linux-
kernel/2014/02/10/54).  This prevents modemmanager from seeing rfcomm0
as a modem. Tried mainline 3.15.6 and works fine.

- a bug in modemmanager/networkmanager.  This keeps rfcomm0 open when
the connection is dropped and causes modemmanager to keep asking the
bluetooth phone about the signal quality.  When you try to connect
again, the connection fails. This is easily worked around by "service
modemmanager restart".

Probably a new bug should be opened on launchpad against the kernel, wrt
the issue of parenting rfcomm0.  This fix should be easy to backport.
But I am a bit discouraged.

-- 
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Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1165433

Title:
  Kernels from 3.8.x to 3.11.x panic on bluetooth DUN disconnect

Status in “linux” package in Ubuntu:
  Incomplete

Bug description:
  Issue is obviously in the kernel that should not panic in any circumnstances.
  This bug is seen on quantal using the kernel from PPA mainline. Tested with 3.8.0 to 3.8.6.
  Since 3.8.x is going to be the raring kernel I believe that this should definitely be fixed before raring is shipped.

  Seen on:

  DELL E6500 with kubuntu quantal 12.10 64 bit and as said, kernel 3.8.6 from the mainline ppa.
  The machine has a Dell Computer Corp. Wireless 370 Bluetooth Mini-card (connected via an internal usb connection).

  The issue is shown when connecting to the internet via a Samsung Galaxy S plus phone, using a bluetooth DUN connection.
  It is reproducible every time.

  How to reproduce:

  1) Use the bluetooth applet to discover the phone and associate to it.
  2) Use network manager to setup a DUN connection with the phone through your APN
  3) Connect to the internet via bluetooth DUN (connection works perfectly)
  4) Disconnect from the network manager.

  At the same time you disconnect, the GUI session is terminated and the
  kernel panics, briefly showing a panic log on the screen.

  Note that:

  a) The issue is not present using the standard ubuntu quantal kernel
  b) The issue is not present using kernels from the mainline ppa before 3.8 (e.g., 3.7.x is fine for all x)
  c) The issue is not present when connecting to the internet using a USB mobile dongle (e.g. Huawei usb key)

  This looks pretty serious to me: kernel does not sync when panicing
  and there is a serious risk of data loss; connecting to the internet
  via a smart phone using bluetooth DUN seems to be something that one
  should take for granted on any modern OS. Furthermore, points a) and
  b) above show that this is a *regression* over previous kernels.

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