Re: kernel oops since changeset e3b8fb8cc214

[Eric Thomas <ethomas@claranet.fr>]

Eric Thomas wrote:
> Hi all,
> 
> My box runs with kernel 2.6.24 + main v4l-dvb tree from HG.
> The card is a Haupauge HVR-3000 running in analog mode only. No *dvd* 
> module loaded.
> Since this videobuf-dma-sg patch, I face kernel oops in several
> situations.
> These problems occur with real tv applications, but traces below come
> from the capture_example binary from v4l2-apps/test.
> 
> 
> capture_example called without any argument, oopses when calling STREAMOFF:
> 
> BUG: unable to handle kernel NULL pointer dereference at virtual address 
> 00000200
> printing eip: c01077e0 *pde = 00000000
> Oops: 0000 [#1] PREEMPT
> Modules linked in: cx8800 compat_ioctl32 cx88_alsa cx88xx ir_common 
> videobuf_dma_sg wm8775 tuner tda9887 tuner_simple tuner_types tveeprom 
> btcx_risc videobuf_core videodev v4l2_common v4l1_compat i2c_dev rfcomm 
> l2cap bluetooth it87 hwmon_vid sunrpc binfmt_misc fglrx(P) snd_intel8x0 
> usb_storage snd_ac97_codec agpgart ac97_bus i2c_nforce2 ati_remote sg 
> sata_nv uhci_hcd ohci_hcd ehci_hcd
> 
> Pid: 3490, comm: capture_example Tainted: P        (2.6.24 #1)
> EIP: 0060:[<c01077e0>] EFLAGS: 00210206 CPU: 0
> EIP is at dma_free_coherent+0x30/0xa0
> EAX: 00200257 EBX: 00000001 ECX: f7206000 EDX: 00001880
> ESI: f7206000 EDI: 00000200 EBP: f78a884c ESP: f70c0d6c
>  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
> Process capture_example (pid: 3490, ti=f70c0000 task=f7881560 
> task.ti=f70c0000)
> Stack: 00200046 00000000 f887672f 00000000 00000000 37206000 f7e3ff68 
> f886e4b2
>        37206000 f98cbbaf f98cb3bb f7e3ff00 f7e3ff84 f7c8ee4c 00200282 
> f990cc26
>        00000000 00000020 f7c8ee4c f8876517 f7c8ee4c f7e3fa80 00000002 
> f7c8ee00
> Call Trace:
>  [<f887672f>] videobuf_waiton+0xdf/0x110 [videobuf_core]
>  [<f886e4b2>] btcx_riscmem_free+0x42/0x90 [btcx_risc]
>  [<f98cbbaf>] videobuf_dma_free+0x4f/0xa0 [videobuf_dma_sg]
>  [<f98cb3bb>] videobuf_dma_unmap+0x2b/0x60 [videobuf_dma_sg]
>  [<f990cc26>] cx88_free_buffer+0x46/0x60 [cx88xx]
>  [<f8876517>] videobuf_queue_cancel+0x97/0xc0 [videobuf_core]
>  [<f88765ca>] __videobuf_streamoff+0x1a/0x30 [videobuf_core]
>  [<f8876638>] videobuf_streamoff+0x18/0x30 [videobuf_core]
>  [<f98ed644>] vidioc_streamoff+0x44/0x60 [cx8800]
>  [<f98ed600>] vidioc_streamoff+0x0/0x60 [cx8800]
>  [<f8855933>] __video_do_ioctl+0xe83/0x3820 [videodev]
>  [<c0200e90>] bit_cursor+0x350/0x5a0
>  [<c02401ff>] n_tty_receive_buf+0x6ff/0xef0
>  [<c024b9a2>] do_con_write+0xaa2/0x19e0
>  [<c013fcb5>] find_lock_page+0x95/0xe0
>  [<f88587ad>] video_ioctl2+0xbd/0x220 [videodev]
>  [<c0118fd3>] release_console_sem+0x1c3/0x210
>  [<c0115880>] __wake_up+0x50/0x90
>  [<c023ad06>] tty_ldisc_deref+0x36/0x90
>  [<c023ccde>] tty_write+0x1be/0x1d0
>  [<c016d008>] do_ioctl+0x78/0x90
>  [<c016d07c>] vfs_ioctl+0x5c/0x2b0
>  [<c023cb20>] tty_write+0x0/0x1d0
>  [<c016d30d>] sys_ioctl+0x3d/0x70
>  [<c0102ace>] sysenter_past_esp+0x5f/0x85
>  =======================
> Code: ce 53 83 ec 10 85 c0 74 06 8b b8 e0 00 00 00 8d 42 ff bb ff ff ff 
> ff c1 e8 0b 90 43 d1 e8 75 fb 9c 58 f6 c4 02 74 3d 85 ff 74 06 <8b> 17 
> 39 d6 73 0f 83 c4 10 89 da 89 f0 5b 5e 5f e9 eb d7 03 00
> EIP: [<c01077e0>] dma_free_coherent+0x30/0xa0 SS:ESP 0068:f70c0d6c
> ---[ end trace d2e4ad244a27b1e7 ]---
> 
> capture_example called with "-r" (read calls) oopses much earlier and
> twice. I can provide traces if useful.
> 
> I'm not skilled enough to fix it myself, but I can test patches.
> 
> Eric
> 

Am'I the only one to face this problem ?
It's clearly related to the changeset e3b8fb8cc214 (Convert
videobuf-dma-sg to generic DMA API).
I don't get how this could only affect my card but not the others.
Maybe this code trigs a bug elsewhere ?

Any help is welcome.

Regards,
Eric

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