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Date: Sat, 16 May 2015 20:16:20 +0300
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Subject: Re: kernel page fault in r8712u
From: Haggai Eran <haggai.eran@gmail.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Florian Schilhabel <florian.c.schilhabel@googlemail.com>,
	linux-wireless@vger.kernel.org
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On 16 May 2015 at 17:57, Larry Finger <Larry.Finger@lwfinger.net> wrote:
> The problem appears to be from r8712u. From the stack dump, the problem
> happens when r8712_free_recvframe() calls __dev_kfree_skb_any(). A
> complication is that my copy of the kernel source does not show such a call.
> :(
>
> Please use gdb to help with the debugging. From the main directory of your
> source, enter the command 'gdb drivers/staging/rtl8712/r8712u.ko'. Once it
> prompts you, enter 'l *r8712_free_recvframe+0x2c'. The first character is
> ell, not one. That will show the actual line of code. Please post that info.

Here's what I get:

(gdb) l *r8712_free_recvframe+0x2c
0x16714 is in r8712_free_recvframe (drivers/staging/rtl8712/rtl8712_recv.c:145).
140             struct _adapter *padapter = precvframe->u.hdr.adapter;
141             struct recv_priv *precvpriv = &padapter->recvpriv;
142
143             if (precvframe->u.hdr.pkt) {
144
dev_kfree_skb_any(precvframe->u.hdr.pkt);/*free skb by driver*/
145                     precvframe->u.hdr.pkt = NULL;
146             }
147             spin_lock_irqsave(&pfree_recv_queue->lock, irqL);
148             list_del_init(&(precvframe->u.hdr.list));
149             list_add_tail(&(precvframe->u.hdr.list),
&pfree_recv_queue->queue);

It seems that dev_kfree_skb_any is an inline function that calls
__dev_kfree_skb_any,
so that should explain why that call didn't show up in the stack dump.

Haggai