Re: [Question] Mlocked count will not be decreased

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

Kefeng Wang wrote:
> 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?

I confirmed your problem also occurs in Linux 4.11 using below testcase.
MemFree is not decreasing while Mlocked is increasing.
Thus, it seems to be statistics accounting bug.

----------
#include <sys/mman.h>
#include <stdlib.h>
#include <unistd.h>

int main(int argc, char ** argv)
{
	int i;
	for (i = 0; i < 128; i++)
		if (fork() == 0) {
			malloc(1048576);
			while (1) {
				mlockall(MCL_CURRENT | MCL_FUTURE);
				munlockall();
			}
		}
	return 0;
}
----------

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