Re: [Em28xx] dvb-core random crashes

On Tue, 10 Jul 2007, Christoph wrote:

> Alan Stern schrieb:
> > On Sun, 8 Jul 2007, Markus Rechberger wrote:
> > 
> >> On 7/8/07, Christoph <[email protected]> wrote:
> >>> Hallo Markus!
> >>>
> >>> I'm using a Pinnacle PCTV DVB-T for several months now without serious
> >>> problems.
> >>> So far I used it only with my Notebook. Now I set up a Mini-ITX Machine with
> >>> MythTV running 24/24h.
> >>>
> >>> The machine freezes ~36h ... black screen, even no sysrq. (Debian etch
> >>> 2.6.18-4-k7).
> >>> So I setup kexec, kernel 2.6.21, v4l 5877:e9a7be188b2b and now I got a
> >>> backtrace:
> >>>
> >>> <1>[16645.528000] BUG: unable to handle kernel NULL pointer dereference at
> >>> virtual address 0
> >>> 0000068
> >>> [...]
> >>> [16645.528000] EIP is at end_unlink_async+0x1b/0xc5 [ehci_hcd]
> >>> [16645.528000] eax: 00000060   ebx: de4f20dc   ecx: df912020   edx: df8f0b57
> >>> [16645.528000] esi: 00000000   edi: de4f20dc   ebp: c58a9d4c   esp: c58a9d40
> >>> [16645.528000] ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
> >>> [16645.528000] Process mythbackend (pid: 12863, ti=c58a8000 task=dbb3d070
> >>> task.ti=c58a8000)
> >>> [16645.528000] Stack: 00000020 00000000 de4f20dc c58a9dbc df8ed7d6 d74ba800
> >>> de4f20dc de4f20d
> >>> c
> >>> [16645.528000]        dd9bd080 c58a9d78 df8ed22a de4f20dc 00000000 de4f20dc
> >>> c58a9de8 df8ed7d
> >>> 6
> >>> [16645.528000]        000000bc c58a9d9c 00000292 00000000 00000000 c56ce254
> >>> de4f20dc 0000000
> >>> 0
> >>> [16645.528000] Call Trace:
> >>> [16645.528000]  [<c0104a3e>] show_trace_log_lvl+0x1a/0x2f
> >>> [16645.528000]  [<c0104aee>] show_stack_log_lvl+0x9b/0xa3
> >>> [16645.528000]  [<c0104cac>] show_registers+0x1b6/0x288
> >>> [16645.528000]  [<c0104e68>] die+0xea/0x1bd
> >>> [16645.528000]  [<c0113bcf>] do_page_fault+0x435/0x506
> >>> [16645.528000]  [<c0289cbc>] error_code+0x74/0x7c
> >>> [16645.528000]  [<df8ed7d6>] ehci_work+0x22/0x64b [ehci_hcd]
> >>> [16645.528000]  [<df8f21b5>] ehci_irq+0x234/0x254 [ehci_hcd]
> >>> [16645.528000]  [<df8a83af>] usb_hcd_irq+0x24/0x51 [usbcore]
> >>> [16645.528000]  [<c013b3e2>] handle_IRQ_event+0x21/0x48
> >>> [16645.528000]  [<c013c515>] handle_level_irq+0x5f/0x96
> >>> [16645.528000]  [<c0105f8a>] do_IRQ+0x5c/0x7a
> >>> [16645.528000]  [<c010453f>] common_interrupt+0x23/0x28
> >>> [16645.528000]  [<c0140892>] free_hot_page+0xa/0xc
> >>> [16645.528000]  [<c01408ae>] __free_pages+0x1a/0x25
> >>> [16645.528000]  [<c014c0bc>] __vunmap+0xa2/0xcb
> >>> [16645.528000]  [<c014c16f>] vfree+0x25/0x27
> >>> [16645.528000]  [<dfb1e77b>] dvb_dvr_release+0x5b/0xb4 [dvb_core]
> >>> [16645.528000]  [<c0155973>] __fput+0xa9/0x153
> >>> [16645.528000]  [<c0155a33>] fput+0x16/0x18
> >>> [16645.528000]  [<c01535cf>] filp_close+0x54/0x5c
> >>> [16645.528000]  [<c0154597>] sys_close+0x57/0x8d
> >>> [16645.528000]  [<c0103b30>] sysenter_past_esp+0x5d/0x81
> >>> [16645.528000]  =======================
> >>> [16645.528000] Code: e0 89 f8 e8 4c 4c 86 e0 83 c4 2c 5b 5e 5f c9 c3 55 89
> >>> e5 57 56 53 89 c3
> >>>  8b 70 14 0f ba b0 bc 00 00 00 01 8d 46 60 ba 57 0b 8f df <c6> 46 68 03 c7
> >>> 46 48 00 00 00 00
> >>>  e8 21 8d 8c e0 8b 7e 58 80 63
> >>> [16645.528000] EIP: [<df8ed1da>] end_unlink_async+0x1b/0xc5 [ehci_hcd]
> > 
> > For whatever it's worth, the crash occurred in end_async_unlink because
> > ehci->reclaim was NULL.  This may imply that ehci->reclaim_ready was
> > set when it shouldn't be.  Don't ask me how either of these could
> > have happened.
> > 
> > Alan Stern
> > 
> 
> mh, how about this:
> drivers/usb/host/ehci-hcd.c:640
> 
>     /* complete the unlinking of some qh [4.15.2.3] */
>     if (status & STS_IAA) {
>         COUNT (ehci->stats.reclaim);
>         ehci->reclaim_ready = 1;
>         bh = 1;
>     }
> ...
>     if (bh)
>         ehci_work (ehci);
> 
> bh was set to 1 ... possible there?!

It is possible; I don't know enough about how the driver works to say
for sure.  You could test it easily enough.  Just add a printk there if
ehci->reclaim is NULL.

> chris
> 
> 
> ps: found the box this morning dead ... the kexec kernel also crashed, same story.
> dvb module was loaded, but mythtv not running. 
> (rc.S was run I messed with the boot options)
> 
> psps: found the box dead again when I came back from work ... 
> no dvb stuff in the backtrace, same story.

Alan Stern


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