BUG: pcmC0D0p:0, pos = 16390, buffer size = 16384, period size = 1024

This change was made by a bot.

Important note: there were no bug when I've installed Trusty Beta. It appeared later, after some updates.

Might be related to the radeon HD audio device. I have Radeon HD 5000 graphics card with HDMI output and the audio works quite ok with alsa, but jackd gives tons of xruns, no matter what period/buffer settings I try. This BUG could be the reason for that. I'm getting this:

BUG: pcmC1D0c:0, pos = 5461, buffer size = 5461, period size = 2730

I tested the 3.14 lowlatency and seems that this bug is fixed for me at least. No more BUG info to kern.log and jackd is able to run just fine. Using kernel:

3.14.0-031400-lowlatency #201403310035 SMP PREEMPT Mon Mar 31 04:44:05 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1305480

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-trusty' to 'verification-done-trusty'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

Upstreamed patch "ALSA: pcm: 'BUG:' message unnecessarily triggers kerneloops" accepted by Takashi Iwai.

On Tue, 13 May 2014, Brad Figg wrote:

> This bug is awaiting verification that the kernel in -proposed solves
> the problem. Please test the kernel and update this bug with the
> results. If the problem is solved, change the tag 'verification-needed-
> trusty' to 'verification-done-trusty'.
>
> If verification is not done by 5 working days from today, this fix will
> be dropped from the source code, and this bug will be closed.

While I did have this problem originally, the kernel upgrades since then
have not shown this issue for me. I have been running the lowlatency
kernel 3.13.0-24-lowlatency since before release on two machines and the
generic version on two more with no problems. So I no longer have a
"broken" machine to test against (do A/B testing).

I'm comfortable that this patch has stopped erroneously triggering apport. Marking verification-done-trusty.

This bug was fixed in the package linux - 3.13.0-27.50

---------------
linux (3.13.0-27.50) trusty; urgency=low

  [ Brad Figg ]

  * Revert "rtlwifi: Set the link state"

linux (3.13.0-27.49) trusty; urgency=low

  [ Brad Figg ]

  * Revert "SAUCE: (no-up) HID: rmi: do not stop the device at the end of
    probe"
  * Revert "SAUCE: (no-up) HID: rmi: introduce RMI driver for Synaptics
    touchpads"
  * Revert "[Config] CONFIG_HID_RMI=m"

linux (3.13.0-26.48) trusty; urgency=low

  [ Benjamin Tissoires ]

  * SAUCE: (no-up) HID: rmi: introduce RMI driver for Synaptics touchpads
    - LP: #1305522
  * SAUCE: (no-up) HID: rmi: do not stop the device at the end of probe
    - LP: #1305522

  [ Kamal Mostafa ]

  * Merged back Ubuntu-3.13.0-24.47 security release
  * Revert "n_tty: Fix n_tty_write crash when echoing in raw mode"
    - LP: #1314762
  * Release Tracking Bug
    - LP: #1316835

  [ Tim Gardner ]

  * [Config] CONFIG_HID_RMI=m
    - LP: #1305522
  * [Config] CONFIG_CRYPTO_DEV_NX=n for ppc64el
    - LP: #1314625
  * [Config] CONFIG_ZSWAP=y
    - LP: #1315203
  * Add rpcsec_gss_krb5 to generic inclusion list
    - LP: #769527

  [ Upstream Kernel Changes ]

  * HID: hidraw: make comment more accurate and nicer
    - LP: #1305522
  * HID: remove hid_get_raw_report in struct hid_device
    - LP: #1305522
  * HID: i2c-hid: implement ll_driver transport-layer callbacks
    - LP: #1305522
  * HID: add inliners for ll_driver transport-layer callbacks
    - LP: #1305522
  * HID: Add transport-driver callbacks to the hid_ll_driver struct
    - LP: #1305522
  * drm/nouveau: fail runtime pm properly.
    - LP: #1313986
  * drm/nouveau: don't suspend/resume display on runtime s/r
    - LP: #1313986
  * n_tty: Fix n_tty_write crash when echoing in raw mode
    - LP: #1314762
    - CVE-2014-0196
  * floppy: ignore kernel-only members in FDRAWCMD ioctl input
    - LP: #1316729
    - CVE-2014-1737
  * floppy: don't write kernel-only members to FDRAWCMD ioctl output
    - LP: #1316735
    - CVE-2014-1738

linux (3.13.0-25.47) trusty; urgency=low

  [ Joseph Salisbury ]

  * Release Tracking Bug
    - LP: #1313868

  [ Adam Lee ]

  * [Config] CONFIG_RTL8723BE=m, CONFIG_RTL8723_COMMON=m
    - LP: #1240940

  [ Alex Hung ]

  * SAUCE: (no-up) dell-led: add mic mute led interface
    - LP: #1308297

  [ Andy Whitcroft ]

  * SAUCE: (no-up) powerpc: Increase COMMAND_LINE_SIZE to 2048 from 512.
    - LP: #1306677

  [ Ben Collins ]

  * [Config] Disable PAMU on Freescale kernels
    - LP: #1311738

  [ Tim Gardner ]

  * Revert "SAUCE: x86, hyperv: bypass the timer_irq_works() check"
    - LP: #1311683
  * SAUCE: (no-up) ALSA: usb-audio: Suppress repetitive debug messages from
    retire_playback_urb()
    - LP: #1305133
  * SAUCE: (no-up) 'BUG:' message unnecessarily triggers kerneloops
    - LP: #1305480
  * [Config] CONFIG_POWERNV_CPUFREQ=m
    - LP: #1309576
  * [Config] CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y for ppc64el
    - LP: #1309576
  * [Config] CONFIG_TRANSPARENT_HUGEPAGE=n for arm64
    - LP: #1309221
  * [Config] CONFIG_MEMCG_KMEM=y
    - LP: #1309586
  * [Config] CONFIG_CRASH_DUMP=y for ppc64el
    - LP: #1312783

  [ Upstream Kernel Change...

This bug was fixed in the package linux - 3.15.0-6.11

---------------
linux (3.15.0-6.11) utopic; urgency=low

  [ Adam Conrad ]

  * Enable building the sata-modules udeb on ppc64el.
    - LP: #1323980
  * [Packaging] Set bootloader and loader on ppc64el to grub

  [ Adam Lee ]

  * SAUCE: (no-up) rtlwifi: rtl8723be: disable MSI interrupts mode
    - LP: #1310512, #1320070

  [ Alex Hung ]

  * SAUCE: (no-up) dell-led: add mic mute led interface
    - LP: #1308297

  [ Andy Whitcroft ]

  * [Config] d-i -- add hyperv_keyboard to serial-modules udeb
    - LP: #1285434
  * [Config] tools -- enable cpupower on ppc64el
  * [Config] ppc64el -- enable perf tools
  * [Config] powerpc -- enable perf tools
  * [Config] ppc64el -- reduce MAX_ORDER with 64k pages
  * [Config] arm64 -- enable tools
    - LP: #1326050
  * [Config] switch hyper-keyboard to virtual
    - LP: #1325306
  * [Config] fix up Breaks/Replaces on linux-cloud-tools-common to fix
    upgrades
  * SAUCE: kvm: BIOS disabled kvm support should be a warning
    - LP: #1300247
  * SAUCE: nouveau: missing outputs should be warnings
    - LP: #1300244
  * [Config] d-i -- add nvme devices to block-modules udeb
    - LP: #1303710

  [ Anton Blanchard ]

  * SAUCE: (no-up) powerpc: 64bit sendfile is capped at 2GB
    - LP: #1328230

  [ Colin Ian King ]

  * SAUCE: intel_pstate: inform user that thermald is worth considering

  [ Dave Chiluk ]

  * [Config] Enable CONFIG_IP_VS_IPV6=y
    - LP: #1300739

  [ Paolo Pisati ]

  * [Config] build vexpress a9 dtb
    - LP: #1303657

  [ Tetsuo Handa ]

  * SAUCE: kthread: Do not leave kthread_create() immediately upon SIGKILL.

  [ Tim Gardner ]

  * Release Tracking Bug
    - LP: #1329045
  * [Debian] Treat vdso install as an environment variable
    - LP: #1325713
  * [Config] Treat vdso install as an environment variable
    - LP: #1325713
  * [config] Set IPMI suppoort default to "y"
  * [Config] powerpc -- CONFIG_SCSI_IBMVSCSI=y
  * [Config] CONFIG_RT_GROUP_SCHED=n
    - LP: #1284731
  * [Config] ppc64el -- switch to 64K system pages
  * [Config] CONFIG_MICROCODE_EARLY=y
  * [Config] SND_DAVINCI_SOC && SND_AM33XX_SOC_EVM =m
  * [Config] armhf: DRM_TILCDC=m
  * SAUCE: (no-up) mei_me: Add module parameter to disable MSI
  * [Config] arm64: KVM=y
  * [Config] armhf: LEDS_TRIGGER_HEARTBEAT=y
  * [Config] armhf: generic: disable CPU_IDLE
  * [Config] armhf: CPU_FREQ=y
  * [Config] Add new mlx modules to d-i
  * [Config] Added Muti-Arch support for linux-headers-PKGVER-ABINUM, linux-tools-common, and linux-cloud-tools-common
    - LP: #1295112
  * [Config] CONFIG_EXYNOS_ADC=n, CONFIG_HW_RANDOM_EXYNOS=n, CONFIG_MMC_DW_EXYNOS=n, CONFIG_USB_DWC3_EXYNOS=n
    - LP: #1294353
  * [Config] CONFIG_ABX500_CORE=y for ppc64el
  * [Config] CONFIG_ALX=m for powerpc
  * [Config] CONFIG_ACENIC_OMIT_TIGON_I=n for ppc64el
  * [Config] CONFIG_ACORN_PARTITION_*=n for ppc64el
  * [Config] CONFIG_ANDROID=n for powerpc
  * [Config] CONFIG_ASYNC_RAID6_TEST=m for ppc64el
  * [Config] CONFIG_BIG_KEYS=y for ppc64el
  * [Config] CONFIG_BSD_PROCESS_ACCT=y for ppc64el
  * rebase to v3.15
  * [Config] CONFIG_PHY_XGENE=y
  * [Config] CONFIG_MLX4_DEBUG=y
    - LP: #1328256
  * [C...

Bug #1551041 affects my hp xw8400 workstation when running 32-bit *Xenial*. Raymond (superquad-vortex2) has helped me identify the problem, and he found, that it is probably caused by what you describe in the following link,

https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/core/pcm_lib.c?id=00d90154404ae6218730068d25bf2faad3186631

that is *this bug*

ALSA: pcm: 'BUG:' message unnecessarily triggers kerneloops
BugLink: http://bugs.launchpad.net/bugs/1305480

The kerneloops-daemon scans dmesg for common crash signatures, among which is 'BUG:'. The message emitted by the PCM library is really a warning, so the most expedient thing to do seems to be to change the string.

See also the Bug report #1551041,

snd_au8820 0000:01:04.0: BUG: , pos = 16386, buffer size = 16384, period size = 1024

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1551041

sudodus, as this report is closed, it has nothing to do with your problem. As you were previously advised in https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1551041/comments/53 , you would want to direct mail the patch author and committer (not post comments on a closed Launchpad report).

I see.