Re: [kselftests] compaction_test is blocked

[Li Zhijian <zhijianx.li@intel.com>]

On 2018年02月11日 13:44, Li Zhijian wrote:
>
>
> On 02/10/2018 05:11 AM, Dan Rue wrote:
>> On Fri, Feb 09, 2018 at 03:53:59PM +0800, Li Zhijian wrote:
>>> Hi
>>>
>>> kselftests is integrated Intel 0Day project.
>>> Sometimes we found compaction_test is blocked for more than 1 hours 
>>> until i kill it.
>>>
>>> Try to figure out where it is running, i added some log to this case.
>>>
>>> the test log is like:
>>> -------------------
>>>   [  111.750543] main: 248
>>>   [  111.750544]-
>>>   [ 111.750821] check_compaction: 98
>>>   [  111.750822]-
>>>   [  111.751102] check_compaction: 105
>>>   [  111.751103]-
>>>   [  111.751362] check_compaction: 111
>>>   [  111.751363]-
>>>   [  111.751621] check_compaction: 118
>>>   [  111.751622]-
>>>   [  111.751879] check_compaction: 123
>>>   [  111.751880]-
>>> -------------------
>>> 118         fprintf(stderr, "%s: %d\n", __func__, __LINE__);
>>> 119         lseek(fd, 0, SEEK_SET);
>>> 120
>>> 121         /* Request a large number of huge pages. The Kernel will 
>>> allocate
>>> 122            as much as it can */
>>> 123         fprintf(stderr, "%s: %d\n", __func__, __LINE__);         
>>> <<<======== the last line we can catch.
>>> 124         if (write(fd, "100000", (6*sizeof(char))) != 
>>> (6*sizeof(char))) {        <<<<============ blocking position
>>> 125                 perror("Failed to write 100000 to 
>>> /proc/sys/vm/nr_hugepages\n");
>>> 126                 goto close_fd;
>>> 127         }
>>> 128
>>> 129         lseek(fd, 0, SEEK_SET);
>>> 130
>>> 131         fprintf(stderr, "%s: %d\n", __func__, __LINE__);
>>> 132         if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
>>> 133                 perror("Failed to re-read from 
>>> /proc/sys/vm/nr_hugepages\n");
>>> 134                 goto close_fd;
>>> 135         }
>>> -------------------
>>>
>>> According to above log and code, it most likely it is blocking at 
>>> the writing operation.
>>>
>>> my environment is like:
>>> OS: debian
>>> kernel: v4.15
>>> model: Ivytown Ivy Bridge-EP
>>> nr_cpu: 48
>>> memory: 64G
>> Hi Zhijian,
>>
>> Please try this patch in mainline:
>>
>>      4c1baad22390 kselftest: fix OOM in memory compaction test
>
> Hi Dan
>
> Thanks for your replies.
>
> I run this case on v4.15, looks this patch is already merged to v4.15.
> lizhijian@inn:~/linux$ git describe 4c1baad
> v4.15-rc2-2-g4c1baad223906

My mistake, this path is not contained by v4.15 yet.
i will have a try.

Thanks



>
> Thanks
>
>> Dan
>>
>>>
>>> NOTE: 0Day can reproduce this issue in 20% on 0Day.
>>>
>>> Anybody can help have a look?
>>>
>>> Thanks
>>> Zhjian
>>>
>>>
>>>
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>>
>> .
>>
>