On 26/10/12 07:35 PM, Greg KH wrote:
On Fri, Oct 26, 2012 at 05:57:23PM -0400, Richard Retanubun wrote:
Hi Guys,
I am debugging a reported kmemleak involving a sierra wireless MC8705 connected
through isp1763 on powerpc linux-3.0.22
Does this also happen on 3.6.3?
thanks,
greg k-h
Hi Greg,
Unfortunately, it is not trivial for us to update the kernel on this platform,
Is there a specific experiment/patch I should look at for 3.0.22?
I will be attempting to use 3.6.3 on another platform, but this may take some time.
I am thinking there may be an action that can be done at /sysfs or /procfs to
do the disconnect without actually removing the power to the device.
I tried "echo 1 > /sys/bus/usb/drivers/usb/2-1.2/remove" and then take down the power
but this produced the same leak signature even before I take down the power.
Update on trigger to problem
============================
This will happen as the modem is powered down and /dev/ttyUSB from sierra is teared down
either by powering it off/removing it, or sending at!reset.
It does not happen when the same thing is done using a simple usb to serial converter (pl2303)
Focusing down on one of the dumps:
unreferenced object 0xd3849740 (size 8):
comm "khubd", pid 1026, jiffies 232553037 (age 506.597s)
hex dump (first 8 bytes):
4d 43 38 37 30 35 00 00 MC8705..
backtrace:
[<e30efd74>] usb_cache_string+0x74/0xac [usbcore]
[<e30e77bc>] usb_enumerate_device+0x44/0xf8 [usbcore]
[<e30e7aa0>] usb_new_device+0x3c/0x13c [usbcore]
[<e30e9824>] hub_thread+0xc8c/0x1544 [usbcore]
[<c0043aa8>] kthread+0x7c/0x80
[<c000ed48>] kernel_thread+0x4c/0x68
I have a small question. How does the memory kmalloc-ed() in usb_cache_string is supposed to be released?
(during usb_serial_disconnect()?) Is the sierra driver is supposed to participate
in the tear down process (in sierra_release() maybe) and not doing something that is expected?
I am still missing the link between the actions done by the hub_thread() for the caching the stings
and the sierra driver code.
Thanks a lot for your time.
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