From: "Måns Rullgård" <mans@mansr.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: linux-usb@vger.kernel.org
Subject: Re: Crash while capturing with usbmon
Date: Fri, 06 Mar 2020 12:38:12 +0000 [thread overview]
Message-ID: <yw1x36alk6a3.fsf@mansr.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.2003051605150.1298-100000@iolanthe.rowland.org> (Alan Stern's message of "Thu, 5 Mar 2020 16:09:05 -0500 (EST)")
Alan Stern <stern@rowland.harvard.edu> writes:
> On Thu, 5 Mar 2020, Måns Rullgård wrote:
>
>> While trying to capture some USB traffic, this happened:
>>
>> 8<--- cut here ---
>> Unable to handle kernel paging request at virtual address ffeff000
> ...
>> [<c069e0a8>] (memcpy) from [<c050c88c>] (mon_copy_to_buff+0x4c/0x6c)
>> [<c050c88c>] (mon_copy_to_buff) from [<c050cd2c>] (mon_bin_event+0x480/0x7b8)
>> [<c050cd2c>] (mon_bin_event) from [<c050ade4>] (mon_bus_complete+0x50/0x6c)
> ...
>
>> It is easily reproducible. What can I do to narrow down the cause?
>
> What kind of USB traffic were you monitoring? Isochronous?
> Scatter-gather?
>
> Can you add printk statements in drivers/usb/mon/mon_bin.c:
> mon_bin_get_data() to determine which of the pathways was used for
> calling mon_copy_buff() and what the values of the arguments were?
OK, I added a printk to mon_bin_get_data(), and the bad call has
offset=4736, length=4096 urb->num_sgs=0 urb->transfer_flags=0x281,
urb->transfer_buffer=0xffefee00.
I guess the question now is how transfer_buffer got assigned that value.
--
Måns Rullgård
next prev parent reply other threads:[~2020-03-06 12:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 19:26 Crash while capturing with usbmon Måns Rullgård
2020-03-05 21:09 ` Alan Stern
2020-03-05 21:53 ` Måns Rullgård
2020-03-06 12:38 ` Måns Rullgård [this message]
2020-03-06 17:27 ` Alan Stern
2020-03-06 17:48 ` Måns Rullgård
2020-03-06 18:18 ` Alan Stern
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