// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 */

#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/mman.h>
#include <linux/mman.h>

#include "kselftest.h"

int main(int argc, char *argv[])
{
        const size_t alloc_size = 2 * 1024 * 1024;
        int retry_count = 10;
        bool dropped;
        void *alloc;

        ksft_print_header();
        ksft_set_plan(1);

        alloc = mmap(0, alloc_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
        if (alloc == MAP_FAILED) {
                if ((errno == EOPNOTSUPP) || (errno == EINVAL)) {
                        ksft_test_result_skip("MAP_DROPPABLE not supported\n");
                        exit(KSFT_SKIP);
                }
                ksft_test_result_fail("mmap error: %s\n", strerror(errno));
                exit(KSFT_FAIL);
        }
        memset(alloc, 'A', alloc_size);

        while (retry_count--) {
                if (madvise(alloc, alloc_size, MADV_PAGEOUT)) {
                        if (errno == EINVAL) {
                                ksft_test_result_skip("madvise(MADV_PAGEOUT) not supported\n");
                                exit(KSFT_SKIP);
                        }
                        ksft_test_result_fail("madvise(MADV_PAGEOUT) error: %s\n", strerror(errno));
                        exit(KSFT_FAIL);
                }

                dropped = memchr(alloc, 'A', alloc_size) == NULL;

                /*
                 * Speculative reference can temporarily prevent some
                 * pages from getting dropped. So sleep and retry.
                 *
                 * If a page is not droppable for 10s, something
                 * is seriously messed up and we want to fail.
                 */
                if (dropped)
                        break;
                sleep(1);
        }

        ksft_test_result(dropped, "madvise(MADV_PAGEOUT) behavior\n");

        ksft_finished();
}