Re: mmapstress06: Convert to new API

Hi Wei,

On Sun, 07 Jun 2026 04:52:06 +0000, Wei Gao wrote:
> mmapstress06: Convert to new API

> +static void cleanup(void)
> +{
> +	if (child_pid > 0) {
> +		SAFE_KILL(child_pid, SIGKILL);
> +		SAFE_WAITPID(child_pid, NULL, 0);
> +	}
> +
> +	if (cg_child) {
> +		SAFE_CG_PRINTF(tst_cg_drain, "cgroup.procs", "%d", getpid());
> +		cg_child = tst_cg_group_rm(cg_child);
> +	}
> +}

The drain step moves the parent process into tst_cg_drain, but the
parent was never placed into cg_child -- only the forked child was
(via SAFE_CG_PRINTF(cg_child, "cgroup.procs", ...) inside the child
block). After SAFE_KILL + SAFE_WAITPID, the child has exited and the
kernel has already removed it from cg_child, so the cgroup is empty
and tst_cg_group_rm() can be called directly.

Draining the parent out of its current cgroup (tst_cg, managed by the
framework) into tst_cg_drain leaves the test process in the wrong
cgroup after cleanup. Compare with ksm02.c, where the drain is correct
because the parent explicitly moves itself into a child cgroup first.

The fix is to drop the SAFE_CG_PRINTF(tst_cg_drain, ...) line:

	if (cg_child)
		cg_child = tst_cg_group_rm(cg_child);

Verdict: Needs revision

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