linux-kernel - Re: [kselftests] compaction

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Date:   Sun, 11 Feb 2018 13:44:41 +0800
From:   Li Zhijian <lizhijian@...fujitsu.com>
To:     Dan Rue <dan.rue@...aro.org>
CC:     <linux-kselftest@...r.kernel.org>,
        "Li, Philip" <philip.li@...el.com>, <linux-kernel@...r.kernel.org>,
        "Li Zhijian(intel)" <zhijianx.li@...el.com>
Subject: Re: [kselftests] compaction_test is blocked



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

Thanks

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

-- 
Best regards.
Li Zhijian (8528)