[LTP] [PATCH 1/2] syscalls/ioctl: ioctl_sg01.c: ioctl_sg01 invoked oom-killer

[Li Wang]

Hi Xinpeng,

I sent to you the case swapping01 solving this(via FILE_LINES_SCANF)
already, feel free to take an reference:
https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/swapping/swapping01.c#L85

On Wed, Jan 27, 2021 at 2:54 PM liuxp11@chinatelecom.cn <
liuxp11@chinatelecom.cn> wrote:

> Hi Li,
> Have a question about using macro SAFE_READ_MEMINFO get MemAvailable
> value,
> Some old kernels maybe not privode "MemAvailable" field, which will
> broken.
>
>
> *From:* Li Wang <liwang@redhat.com>
> *Date:* 2021-01-27 12:27
> *To:* Xinpeng Liu <liuxp11@chinatelecom.cn>
> *CC:* LTP List <ltp@lists.linux.it>
> *Subject:* Re: [LTP] [PATCH 1/2] syscalls/ioctl: ioctl_sg01.c: ioctl_sg01
> invoked oom-killer
> Hi Xinpeng,
>
> On Wed, Jan 27, 2021 at 11:28 AM Xinpeng Liu <liuxp11@chinatelecom.cn>
> wrote:
>
>> Kernel version is 5.4.81+,the available RAM is less than free,as follow:
>> [root@liuxp mywork]# head /proc/meminfo
>> MemTotal:       198101744 kB
>> MemFree:        189303148 kB
>> MemAvailable:   188566732 kB
>>
>> So use available RAM to avoid OOM killer.
>>
>> Signed-off-by: Xinpeng Liu <liuxp11@chinatelecom.cn>
>> ---
>>  lib/tst_memutils.c | 29 ++++++++++++++++++++++++++---
>>  1 file changed, 26 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/tst_memutils.c b/lib/tst_memutils.c
>> index dd09db4..21df9a8 100644
>> --- a/lib/tst_memutils.c
>> +++ b/lib/tst_memutils.c
>> @@ -10,14 +10,33 @@
>>
>>  #define TST_NO_DEFAULT_MAIN
>>  #include "tst_test.h"
>> +#include "tst_safe_stdio.h"
>>
>>  #define BLOCKSIZE (16 * 1024 * 1024)
>>
>> +static unsigned long get_available_ram(void)
>> +{
>> +       char buf[60]; /* actual lines we expect are ~30 chars or less */
>> +       unsigned long available_kb = 0;
>> +       FILE *fp;
>> +
>> +       fp = SAFE_FOPEN("/proc/meminfo","r");
>> +       while (fgets(buf, sizeof(buf), fp)) {
>> +               if (sscanf(buf, "MemAvailable: %lu %*s\n", &available_kb)
>> == 1){
>> +                       break;
>> +               }
>> +       }
>> +       SAFE_FCLOSE(fp);
>> +
>> +       return 1024 * available_kb;
>> +}
>> +
>>  void tst_pollute_memory(size_t maxsize, int fillchar)
>>  {
>>         size_t i, map_count = 0, safety = 0, blocksize = BLOCKSIZE;
>>         void **map_blocks;
>>         struct sysinfo info;
>> +       unsigned long available_ram = get_available_ram();
>>
>
> LTP provides SAFE_READ_MEMINFO() macro to be used in /proc/meminfo reading.
> See:
> https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/swapping/swapping01.c#L85
>
>
>
>>
>>         SAFE_SYSINFO(&info);
>>         safety = MAX(4096 * SAFE_SYSCONF(_SC_PAGESIZE), 128 * 1024 *
>> 1024);
>> @@ -26,15 +45,19 @@ void tst_pollute_memory(size_t maxsize, int fillchar)
>>         if (info.freeswap > safety)
>>                 safety = 0;
>>
>> +       /*"MemAvailable" field maybe not exist, or freeram less than
>> available_ram*/
>> +       if(available_ram == 0 || info.freeram < available_ram)
>> +               available_ram = info.freeram;
>> +
>>         /* Not enough free memory to avoid invoking OOM killer */
>> -       if (info.freeram <= safety)
>> +       if (available_ram <= safety)
>>                 return;
>>
>>         if (!maxsize)
>>                 maxsize = SIZE_MAX;
>>
>> -       if (info.freeram - safety < maxsize / info.mem_unit)
>> -               maxsize = (info.freeram - safety) * info.mem_unit;
>> +       if (available_ram - safety < maxsize / info.mem_unit)
>> +               maxsize = (available_ram - safety) * info.mem_unit;
>>
>>         blocksize = MIN(maxsize, blocksize);
>>         map_count = maxsize / blocksize;
>> --
>> 1.8.3.1
>>
>>
>> --
>> Mailing list info: https://lists.linux.it/listinfo/ltp
>>
>>
>
> --
> Regards,
> Li Wang
>
>

-- 
Regards,
Li Wang
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