testcases/kernel/syscalls/setrlimit/setrlimit04.c

/*
 *   Copyright (C) 2017 Red Hat, Inc.  All rights reserved.
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   DESCRIPTION
 *     Attempt to run a trivial binary with stack < 1MB.
 *
 *     Early patches for stack guard gap caused that gap size was
 *     contributing to stack limit. This caused failures
 *     for new processes (E2BIG) when ulimit was set to anything
 *     lower than size of gap. commit 1be7107fbe18 "mm: larger
 *     stack guard gap, between vmas" sets default gap size to 1M
 *     (for systems with 4k pages), so let's set stack limit to 512kB
 *     and confirm we can still run some trivial binary.
 */

#define _GNU_SOURCE
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/wait.h>

#include "tst_test.h"

#define STACK_LIMIT (512 * 1024)

static void test_setrlimit(void)
{
	int status;
	struct rlimit rlim;
	pid_t child;

	rlim.rlim_cur = STACK_LIMIT;
	rlim.rlim_max = STACK_LIMIT;

	SAFE_SETRLIMIT(RLIMIT_STACK, &rlim);

	child = SAFE_FORK();
	if (child == 0)
		SAFE_EXECLP("/bin/true", "/bin/true", NULL);
	SAFE_WAITPID(child, &status, 0);

	if (WIFEXITED(status)) {
		if ((WEXITSTATUS(status) == 0))
			tst_res(TPASS, "child process completed OK");
		else
			tst_res(TFAIL, "child process exited with %d",
				WEXITSTATUS(status));
	} else if (WIFSIGNALED(status)) {
		tst_res(TFAIL, "child exited with signal %s",
			tst_strsig(WTERMSIG(status)));
	}
}

static struct tst_test test = {
	.test_all     = test_setrlimit,
	.forks_child  = 1,
	.needs_root = 1,
};