[dpdk-users] BUG: unable to handle kernel paging request

Wiles, Keith keith.wiles at intel.com
Fri Feb 24 00:41:53 CET 2017

> On Feb 23, 2017, at 2:38 PM, Sushil Adhikari <sushil446 at gmail.com> wrote:
> While trying to run dpdk Kni application I ran in to a problem, with
> following error message
> BUG: unable to handle kernel paging request at 000007ffe2b92780
> To run the application I first unbinded the ports from kernel module and
> binded them to igb_uio
>> echo 0000:05:00.1 > /sys/bus/pci/drivers/ixgbe/unbind
>> echo 0000:05:00.0 > /sys/bus/pci/drivers/ixgbe/unbind
>> echo 0x8086 0x1528 > /sys/bus/pci/drivers/igb_uio/new_id
> I ran the application using gdb as
> [~]$ /root/gdb dpdkKni
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> Reading symbols from dpdkKni...(no debugging symbols found)...done.
> (gdb) Run dpdkKni -c 0x0f -n 4 -- -P -p 0x3 --config="(0,0,1),(1,2,3)"
> Starting program: /root/dpdkKni dpdkKni -c 0x0f -n 4 -- -P -p 0x3
> --config="(0,0,1),(1,2,3)"
> warning: Could not load shared library symbols for linux-vdso.so.1.
> Do you need "set solib-search-path" or "set sysroot"?
> warning: Unable to find libthread_db matching inferior's thread library,
> thread debugging will not be available.
> EAL: Detected 4 lcore(s)
> EAL: Probing VFIO support...
> EAL: PCI device 0000:05:00.0 on NUMA socket -1
> EAL:   probe driver: 8086:1528 net_ixgbe
> EAL: PCI device 0000:05:00.1 on NUMA socket -1
> EAL:   probe driver: 8086:1528 net_ixgbe
> Address of pktmbuf_pool 0x7ffff5a7dec0
> APP: Initialising port 0 ...
> KNI: pci: 05:00:00       8086:1528
> kni created for port 0 with kni[i] address 0x7fff75638280 with i 0
> APP: Initialising port 1 ...
> KNI: pci: 05:00:01       8086:1528
> kni created for port 1 with kni[i] address 0x7fff75629e00 with i 0
> APP: Lcore 1 is writing to port 0
> APP: Lcore 2 is reading from port 1
> APP: Lcore 3 is writing to port 1
> APP: Lcore 0 is reading from port 0
> ^C
> Program received signal SIGINT, Interrupt.

The program did not crash or get a segfault, but you hit control-c which stopped the application. When you ran the application you started 4 threads and this is why it would appear in different places when stopped.

If the application is hanging then you can use control-C and then do ‘info threads’ command to see the location of all threads. You can use the ‘thread X’ command to switch between threads. Please check the command usage here I am going from memory.

I am not sure if the application has a -i option to get a command line if so that maybe useful to enable, check the application to see if it used cmdline feature.

It maybe the application just sits running and you have to use other tools or apps to send traffic on the KNI application, sorry I have not really used the KNI example.

> 0x000000000044e916 in rte_kni_tx_burst ()
> (gdb) backtrace
> #0  0x000000000044e916 in rte_kni_tx_burst ()
> #1  0x0000000000619758 in main_loop(void*) ()
> #2  0x0000000000431183 in rte_eal_mp_remote_launch ()
> #3  0x000000000040d312 in main ()
> (this is where the program crashes)
> I tried to trace the crash with gdb(I am new to gdb)
> and when I do the backtrace it ends up in different functions each time:
> this time it gave me rte_kni_tx_burst()
> I'm running latest dpdk version 17.02 and linux kernel is
> Linux version 4.4.20 (tcuser at cibuild08) (gcc version 4.9.2 (crosstool-NG
> 1.20.0) ) #1 SMP
> I would appreciate any suggestion or insight regarding this issue.


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