Re: [dpdk-users] segmentation fault after using rte_malloc()

["Wiles, Keith" <keith.wiles@intel.com>]

> On Apr 24, 2019, at 9:22 AM, 曾懷恩 <the@csie.io> wrote:
> 
> Hi Keith,
> 
> I have tried DPDK 19.05-rc2, 19.02, 18.11 on VMware e1000 driver, Dell R630 with Mellanox Connectx-3 and Intel X520
> 
> However I still got segmentation fault with all above setting

So you are using the simple example and you get a invalid rte_malloc memory?

I do not know how to debug this problem as it sounds like a race condition or memory corruption.

The simple example code is doing the right things to use that API, so if you are getting the same memory address returned then I would use GDB and set a hardware break point to try to see where this is going wrong. Not much help as I can not reproduce the problem.

We know that DPDK works, what we need to find out is why it does not work in your platform. Try different size mallocs, but just shooting in the dark here. Now rte_malloc(2) of two bytes is a real waste of memory as the over head for a 2 byte request is very high.

> 
> here are my settings : 
> 
> With CX3 
> 
> modprobe -a ib_uverbs mlx4_en mlx4_core mlx4_ib
> /etc/init.d/openibd restart
> ls -d /sys/class/net/*/device/infiniband_verbs/uverbs* | cut -d / -f 5
> {
>    for intf in ens3 ens8;
>    do
>        (cd "/sys/class/net/${intf}/device/" && pwd -P);
>    done;
> } |
> sed -n 's,.*/\(.*\),-w \1,p'
> mount -t hugetlbfs nodev /mnt/huge
> 
> With X520 and e1000:
> 
> mount -t hugetlbfs nodev /mnt/huge
> modprobe uio
> insmod dpdk-18.11/x86_64-native-linuxapp-gcc/kmod/igb_uio.ko
> /root/dpdk-18.11//usertools/dpdk-devbind.py --bind=igb_uio 00:0a.0
> /root/dpdk-18.11//usertools/dpdk-devbind.py --bind=igb_uio 00:08.0
> 
> My OS is CentOS 7.5 in KVM with SRIOV enable
> 
> hugepage size is set to 2MB
> 
> Thanks for reply
> 
> Best Regard,
> 
>> 曾懷恩 <the@csie.io> 於 2019年4月24日 上午1:34 寫道：
>> 
>> Hi Keith,
>> 
>> Yes I ran this program as root 
>> 
>> However I ran it with DPDK 18.11 release.
>> 
>> I will try 19.05 later.
>> 
>> Besides, my cpu is E5-2650 v4.
>> NICs are Intel x520 DA2 and Mellanox connectx-3
>> 
>> thank you for reply
>> 
>> Best Regards,
>> 
>> 
>> 
>> 
>>> Wiles, Keith <keith.wiles@intel.com> 於 2019年4月22日 下午9:09 寫道：
>>> 
>>> 
>>> 
>>>> On Apr 22, 2019, at 1:43 AM, 曾懷恩 <the@csie.io> wrote:
>>>> 
>>>> Hi Wiles,
>>>> 
>>>> here is my sample code with just doing rte_eal_init() and rte_malloc() .
>>>> 
>>>> 
>>>> 
>>> 
>>> I tried the attached code and it works on my machine with something close to DPDK 19.05 release.
>>> 
>>> I only use 2 Meg pages, but I assumed it would not make any difference.
>>> 
>>> Did you run this example as root?
>>>> 
>>>> And my start eal cmdline option is ./build/test -l 0-1 -n 4
>>>> 
>>>> Thank you very much for your reply
>>>>> Wiles, Keith <keith.wiles@intel.com> 於 2019年4月21日 上午4:29 寫道：
>>>>> 
>>>>> 
>>>>> 
>>>>> Sent from my iPhone
>>>>> 
>>>>>> On Apr 18, 2019, at 11:31 PM, 曾懷恩 <the@csie.io> wrote:
>>>>>> 
>>>>>> HI, Stephen,
>>>>>> 
>>>>>> Yes, I set huge page in  default_hugepagesz=1G hugepagesz=1G hugepages=4
>>>>>> 
>>>>>> and also did rte_eal_init at the beginning of my program.
>>>>>> 
>>>>>> thanks for reply.
>>>>> 
>>>>> Is the core doing the rte_malloc one of the cores listed in the core list on the command line.  In other words the pthread doing the allocation should be the master lcore or one of the slave lcores.
>>>>> 
>>>>> Also I seems like a very simple test case, can you do the rte_eal_init() and then do the allocation as your sample code looks and then exit? Does this cause a segfault?
>>>>>> 
>>>>>> 
>>>>>>> Stephen Hemminger <stephen@networkplumber.org> 於 2019年4月19日 上午10:59 寫道：
>>>>>>> 
>>>>>>> On Fri, 19 Apr 2019 09:11:05 +0800
>>>>>>> 曾懷恩 <the@csie.io> wrote:
>>>>>>> 
>>>>>>>> Hi all, 
>>>>>>>> 
>>>>>>>> i have 1 problem while using rte_malloc
>>>>>>>> 
>>>>>>>> Every time I use this function and use the memory it returns, it shows segmentation fault(core dump)
>>>>>>>> 
>>>>>>>> Is something wrong?
>>>>>>>> 
>>>>>>>> thanks.
>>>>>>>> 
>>>>>>>> 
>>>>>>>> rte init …
>>>>>>>> ………...
>>>>>>>> unsigned char *str1;
>>>>>>>> printf("str1 addr = %x\n", str1);
>>>>>>>> str1 = rte_malloc(NULL,2,RTE_CACHE_LINE_SIZE);
>>>>>>>> printf("str1 addr = %x\n", str1);
>>>>>>>> str1[0] = 'a’; //segmentation fault here
>>>>>>>> str1[1] = '\0';
>>>>>>> Do you have huge pages?
>>>>>>> Did you do eal_init?
>>>>>> 
>>>> 
>>>> <test.c><Makefile>
>>> 
>>> Regards,
>>> Keith
>>> 
> 

Regards,
Keith