On Tue, 30 Aug 2016, Richard van der Hoff wrote:
> I have a USB-3.1 dock; sometimes I see a kernel panic when I unplug it,
> which hangs the entire system. It appears that the first unplug is
> successful; the second one normally triggers a crash.
>
> The situation is complicated by the fact that this USB bridge is behind
> a chain of PCI bridges, which appear to power down when nothing is
> plugged into the USB-C port.
>
> Greg K-H hinted via Bugzilla that this might be an area which is already
> under development, in which case, apologies for the noise; but I'd be
> interested in understanding a bit more about the problem, in any case.
>
>
> The diagnostics below were all collected on kernel 4.7.0.
>
> The start of the panic, as captured over a serial console, is as follows:
>
> [ 44.010232] BUG: unable to handle kernel NULL pointer dereference at
> (null)
> [ 44.010274] IP: [<ffffffff81630316>] usb_hc_died+0x16/0xc0
> [ 44.010292] PGD 0
> [ 44.010300] Oops: 0000 [#1] SMP
> [ 44.010310] Modules linked in: xt_CHECKSUM iptable_mangle
> ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat
> nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack ipt_REJECT
> nf_reject_ipv4
>
> ... and that's as far as it gets.
Please try applying the patch at the bottom of this email:
http://marc.info/?l=linux-usb&m=147195533502706&w=2
There's a good chance it will fix your problem.
Alan Stern
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