[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <509D804A.7080807@ruggedcom.com>
Date: Fri, 9 Nov 2012 17:14:34 -0500
From: Richard Retanubun <richardretanubun@...gedcom.com>
To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Alan Stern <stern@...land.harvard.edu>, Greg KH <greg@...ah.com>,
Lennart Sorensen <lsorense@...lub.uwaterloo.ca>,
Tang Nguyen <TangNguyen@...gedcom.com>,
linux-usb mailing list <linux-usb@...r.kernel.org>
Subject: Re: kmemleak report on isp1763 and sierra MC8705
On 29/10/12 06:14 PM, Alan Stern wrote:
> On Mon, 29 Oct 2012, Richard Retanubun wrote:
>> 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()?)
>
> It doesn't get released during usb_serial_disconnect(). It gets
> released during usb_release_dev() in drivers/usb/core/usb.c.
>
>> Is the sierra driver is supposed to participate
>> in the tear down process (in sierra_release() maybe) and not doing something that is expected?
>
> Probably not.
>
>> I am still missing the link between the actions done by the hub_thread() for the caching the stings
>> and the sierra driver code.
>
> They aren't all that closely related.
>
> usb_release_dev() won't be called until all references to the USB
> device have been dropped. Maybe there's an extra reference hanging
> around.
>
> Alan Stern
>
Thanks a lot for the hint Alan.
I added a dev_dbg print in usb_release_dev() and saw that in the builds where there is a leak, this was simply never called!
the last line printed in a trace with all dev_dbg on is this "usb_disable_device nuking all URBs"
When the sierra modem is unplugged, the cleanup sequence never calls usb_release_dev() (on PL2303 it always calls usb_release_dev()
This is the current state of versions from linux-stable
3.0.y (3.0.51) - Have the issue
3.2.y (3.2.33) - Have the issue
3.4.y (3.4.18) - Have the issue
3.5.y (3.5.7) - Does not have the issue (but leaks because the portdata patches is not backported yet)
3.6.y (3.6.6) - Does not have the issue
So a diff between 3.4.y and 3.5.y ought to narrow it down further.
I am posting just in case someone recalls a particular patch I should be trying out first...
-- RR --
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists