[Question] Mlocked count will not be decreased

[Kefeng Wang]

Hi All,

Mlocked in meminfo will be increasing with an small testcase, and never be 
released in mainline,
here is a testcase[1] to reproduce the issue, but the centos7.2/7.3 will not 
increase.

Is it normal?

Thanks,
Kefeng




[1] testcase
linux:~ # cat test_mlockall.sh
grep Mlocked /proc/meminfo
 for j in `seq 0 10`
 do
        for i in `seq 4 15`
        do
                ./p_mlockall >> log &
        done
        sleep 0.2
done
grep Mlocked /proc/meminfo


linux:~ # cat p_mlockall.c
#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>

#define SPACE_LEN       4096

int main(int argc, char ** argv)
{
        int ret;
        void *adr = malloc(SPACE_LEN);
        if (!adr)
                return -1;
        
        ret = mlockall(MCL_CURRENT | MCL_FUTURE);
        printf("mlcokall ret = %d\n", ret);

        ret = munlockall();
        printf("munlcokall ret = %d\n", ret);

        free(adr);
        return 0;
}