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

[Li Wang]

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
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