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Date: Wed, 27 Oct 2010 10:32:47 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: marui <m00150988@huawei.com>
Cc: Greg KH <greg@kroah.com>, Alan Stern <stern@rowland.harvard.edu>,
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        zihan@huawei.com, wangyeqi@huawei.com
Subject: Re: [PATCH] fix oops in usbserial_cleanup function
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> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999651] serial_cleanup - port 5
> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999653] destroy_serial - (null)

So someone called destroy serial with serial->type->desc NULL

> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999654] return_serial
> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999671] BUG: unable to handle kernel NULL pointer dereference at (null)
> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999675] IP: [<(null)>] (null)

And serial->type->release NULL

> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999762]  [<fb877b40>] ? destroy_serial+0x80/0xd0 [usbserial]
> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999765]  [<fb877ac0>] ? destroy_serial+0x0/0xd0 [usbserial]
> Oct 27 00:20:10 linux-mec9 kernel: [ 6441.999770]  [<c03f351a>] ? kref_put+0x2a/0x60

Which came from the tty close (which will be after the hangup if you
pulled the card out with the modem in use). Kref leak perhaps ?

What driver is actually being used for the card itself ?

Alan