kernel BUG in videobuf-dma-sg.c

Hello,

I am a KnoppMyth user experiencing some trouble with the saa7134-alsa module. The module loads fine, but as soon as I launch MythTV and try to use the tuner, the application locks up and I get a message about a kernel bug.

I have tried compiling and using several different versions of the v4l drivers (including the most recent), but to no avail. Also, there is another KnoppMyth user experiencing the same issue.

I thought my problem might be fixed by using the drivers that included this
patch: http://linuxtv.org/hg/v4l-dvb/rev/b978c6ede10a , but that did not work either.

Here is the output from dmesg after the error:

saa7134 ALSA driver for DMA sound loaded

saa7133[0]/alsa: saa7133[0] at 0xdc001000 irq 5 registered as card -1

{here is where I launched mythfrontend and began using the tuner}

magic mismatch: 0 (expected 19721112)

------------[ cut here ]------------

kernel BUG at /home/gjm/v4l-dvb-b978c6ede10a/v4l/videobuf-dma-sg.c:278!

invalid opcode: 0000 [#1]

PREEMPT SMP

Modules linked in: saa7134_alsa autofs4 nfsd exportfs cx8800 cx88xx bttv

btcx_risc lirc_i2c lirc_dev ipv6 af_packet fuse usbhid ff_memless pcmcia yenta_socket rsrc_nonstatic pcmcia_core aufs sbp2 ohci1394 ieee1394 usb_storage ohci_hcd ehci_hcd nvram wm8775 cx25840 snd_via82xx gameport snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss ivtv snd_pcm saa7115 snd_page_alloc snd_mpu401_uart snd_seq_dummy snd_seq_oss hostap_pci hostap ieee80211_crypt_rtl msp3400 snd_seq_midi snd_seq_midi_event tuner_simple tuner_types snd_seq snd_timer tuner snd_rawmidi orinoco_pci orinoco hermes via686a hwmon snd_seq_device firmware_class 8250_pnp 8250 saa7134 compat_ioctl32 i2c_algo_bit serial_core videobuf_dma_sg videobuf_core cx2341x i2c_viapro via_agp v4l2_common videodev v4l1_compat agpgart uhci_hcd ir_kbd_i2c ir_common tveeprom snd i2c_core parport_pc parport shpchp pci_hotplug usbcore prism2_pci p80211 soundcore pcspkr rtc_cmos rtc_core rtc_lib evdev tsdev

CPU: 0

EIP: 0060:[<f0c93438>] Not tainted VLI

EFLAGS: 00010292 (2.6.23-chw-4 #1)

EIP is at videobuf_dma_unmap+0x58/0x60 [videobuf_dma_sg]

eax: 00000029 ebx: efaf50cc ecx: ffffffff edx: 00000000

esi: e74c53c0 edi: df511400 ebp: e405ff44 esp: e405fe24

ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068

Process mythbackend (pid: 3304, ti=e405e000 task=eff5a1d0 task.ti=e405e000)

Stack: f0c94218 00000000 19721112 efaf5000 f0c93451 e405fe9d f0dd25a3

00000000

       e15915e0 eff5a220 00000000 e74c53c0 e34fca44 e295d720 eff23448

eacac1f4

       e34fc800 e3ab7000 e15915e0 00000af5 00000000 e34fc4a4 e34fc558

00000000

Call Trace:

 [<f0c93451>] videobuf_sg_dma_unmap+0x11/0x20 [videobuf_dma_sg]

 [<f0dd25a3>] snd_pcm_oss_change_params+0x1f3/0xd80 [snd_pcm_oss]

 [<f0dd353b>] snd_pcm_oss_get_active_substream+0x5b/0x70 [snd_pcm_oss]

 [<c0567c1d>] __mutex_lock_slowpath+0x12d/0x290

 [<f178e564>] snd_card_saa7134_hw_free+0x44/0x70 [saa7134_alsa]

 [<f0dc0f36>] snd_pcm_release_substream+0x36/0x70 [snd_pcm]

 [<f0dd3709>] snd_pcm_oss_release_file+0x19/0x30 [snd_pcm_oss]

 [<f0dd4ee4>] snd_pcm_oss_release+0x44/0xa0 [snd_pcm_oss]

 [<c01854d2>] __fput+0xa2/0x1d0

 [<c01824b7>] filp_close+0x47/0x80

 [<c01838b9>] sys_close+0x69/0xc0

 [<c0104412>] syscall_call+0x7/0xb

=======================

Code: c7 43 14 00 00 00 00 c7 43 18 00 00 00 00 83 c4 0c 5b c3 c7 44 24 08

12 11 72 19 89 44 24 04 c7 04 24 18 42 c9 f0 e8 b8 65 49 cf <0f> 0b eb fe 0f 0b eb fe 81 ec ec 00 00 00 89 44 24 24 89 e0 e8

EIP: [<f0c93438>] videobuf_dma_unmap+0x58/0x60 [videobuf_dma_sg] SS:ESP 0068:e405fe24

root@mythtv:/home/gjm#

root@mythtv:/home/gjm# uname -a

Linux mythtv 2.6.23-chw-4 #1 SMP PREEMPT Mon May 26 14:44:56 PDT 2008 i686 GNU/Linux

The function in which the error appears in videobuf-dma-sg.c is this:

int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)

{

        MAGIC_CHECK(dma->magic, MAGIC_DMABUF); /* this is line 278 in the

last driver I tried */

        if (!dma->sglen)

                return 0;

 

        dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);

 

        kfree(dma->sglist);

        dma->sglist = NULL;

        dma->sglen = 0;

        return 0;

}

If you need any more information, please let me know.

Thanks,

Gabriel

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