Cfrtjryk

i am getting this kernel panic on mips running linux. I have my own network device called foodevice and sometimes on device shutdown i get this error. I figured something in the skb may be null so I am trying to use gdb commands to help me pinpoint where to look.

CPU 0 Unable to handle kernel paging request at virtual address 00000000,     epc == 8020913c, ra == 802090fc  

[ 2685.740000] Oops[#1]:                                                                                                  

[ 2685.740000] Cpu 0                                                                                                      

[ 2685.740000] $ 0   : 00000000 00000000 00002000 8fad8600                                                                

[ 2685.740000] $ 4   : 000000e8 8e900441 00000004 00004305                                                                

[ 2685.740000] $ 8   : 8f95ffe0 0000dc00 00000000 8030e000                                                                

[ 2685.740000] $12   : 0000001f 001f0041 00000001 00480000                                                                

[ 2685.740000] $16   : 00000000 8faef780 8ea19000 8fad86e8                                                                

[ 2685.740000] $20   : 00000000 00000000 00000001 80310000                                                                

[ 2685.740000] $24   : 004812d8 800973cc                                                                                  

[ 2685.740000] $28   : 8f95e000 8f95fd68 00000040 802090fc                                                                

[ 2685.740000] Hi    : 00000011                                                                                           

[ 2685.740000] Lo    : 0000001b                                                                                           

[ 2685.740000] epc   : 8020913c dev_queue_xmit+0x90/0x454                                                                 

[ 2685.740000]     Tainted: G           O                                                                                 

[ 2685.740000] ra    : 802090fc dev_queue_xmit+0x50/0x454                                                                 

[ 2685.740000] Status: 1100dc03    KERNEL EXL IE                                                                          

[ 2685.740000] Cause : 00800008                                                                                           

[ 2685.740000] BadVA : 00000000                                                                                           

[ 2685.740000] PrId  : 00019750 (MIPS 74Kc)                                                                               

[ 2685.740000] Modules linked in: batman_adv crc16 foodevice(O) antctl(O)     rlp(O) xsysfs(O) sal(O) usb_storage cdc_acm ath79_)

[ 2685.740000] Process kworker/0:1 (pid: 237, threadinfo=8f95e000,     task=8f8259e8, tls=00000000)                           

[ 2685.740000] Stack : 8f8259e8 803171b8 803171b8 80097408 8f95e000 8f95fda0     8f37e380 8faef798                            

[ 2685.740000]         8f37e380 00000000 00000000 8ea70f74 00000000 8f8259e8     803171b8 80294d7c                            

[ 2685.740000]         8faef780 8f37e380 8faef798 8f37e600 00000000 00000040     00000001 80310000                            

[ 2685.740000]         00000001 8ea714c0 00000000 8f939600 00000001 00000004     8f939628 801d5274                            

[ 2685.740000]         8f939800 8f37e380 8ea4ac00 00246742 8f389c00 80310000     00000000 8ea7b3e0                            

[ 2685.740000]         ...                                                                                                

[ 2685.740000] Call Trace:                                                                                                

[ 2685.740000] [<8020913c>] dev_queue_xmit+0x90/0x454                                                                     

[ 2685.740000] [<8ea70f74>] saDevUninit+0x398/0xf78 [foodevice]                                                              

[ 2685.740000]                                                                                                            

[ 2685.740000]                                                                                                            

[ 2685.740000] Code: 00839821  8e700004  a622007a <8e020000> 50400094      8e4200fc  8e22004c  ae220018  8e050014             

[ 2686.010000] ---[ end trace 0f2f0a8123e4bc82 ]---                                                                       

[ 2686.020000] Kernel panic - not syncing: Fatal exception in interrupt 

So i believe i am looking for a null pointer somewhere but am a little confused as to where its telling me.

doing (gdb) list *0x8020913c gives me:

0x8020913c is in dev_hard_start_xmit (net/core/dev.c:2207).

2202     *     support DMA from it.

2203     */

2204    static inline int skb_needs_linearize(struct sk_buff *skb,

2205                          int features)

2206    {

2207        return skb_is_nonlinear(skb) &&

2208                ((skb_has_frag_list(skb) &&

2209                    !(features & NETIF_F_FRAGLIST)) ||

2210                (skb_shinfo(skb)->nr_frags &&

2211                    !(features & NETIF_F_SG)));

Is it telling me that skb_is_nonlinear crashing?