// SPDX-License-Identifier: GPL-2.0
/*
 *
 * A test for the patch "Allow compaction of unevictable pages".
 * With this patch we should be able to allocate at least 1/4
 * of RAM in huge pages. Without the patch much less is
 * allocated.
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>

#include "kselftest.h"

#define MAP_SIZE_MB     100
#define MAP_SIZE        (MAP_SIZE_MB * 1024 * 1024)

struct map_list {
        void *map;
        struct map_list *next;
};

int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize)
{
        char  buffer[256] = {0};
        char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'";
        FILE *cmdfile = popen(cmd, "r");

        if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
                ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
                return -1;
        }

        pclose(cmdfile);

        *memfree = atoll(buffer);
        cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'";
        cmdfile = popen(cmd, "r");

        if (!(fgets(buffer, sizeof(buffer), cmdfile))) {
                ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno));
                return -1;
        }

        pclose(cmdfile);
        *hugepagesize = atoll(buffer);

        return 0;
}

int prereq(void)
{
        char allowed;
        int fd;

        fd = open("/proc/sys/vm/compact_unevictable_allowed",
                  O_RDONLY | O_NONBLOCK);
        if (fd < 0) {
                ksft_print_msg("Failed to open /proc/sys/vm/compact_unevictable_allowed: %s\n",
                               strerror(errno));
                return -1;
        }

        if (read(fd, &allowed, sizeof(char)) != sizeof(char)) {
                ksft_print_msg("Failed to read from /proc/sys/vm/compact_unevictable_allowed: %s\n",
                               strerror(errno));
                close(fd);
                return -1;
        }

        close(fd);
        if (allowed == '1')
                return 0;

        ksft_print_msg("Compaction isn't allowed\n");
        return -1;
}

int check_compaction(unsigned long mem_free, unsigned long hugepage_size,
                     unsigned long initial_nr_hugepages)
{
        unsigned long nr_hugepages_ul;
        int fd, ret = -1;
        int compaction_index = 0;
        char nr_hugepages[20] = {0};
        char init_nr_hugepages[24] = {0};
        char target_nr_hugepages[24] = {0};
        int slen;

        snprintf(init_nr_hugepages, sizeof(init_nr_hugepages),
                 "%lu", initial_nr_hugepages);

        /* We want to test with 80% of available memory. Else, OOM killer comes
           in to play */
        mem_free = mem_free * 0.8;

        fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
        if (fd < 0) {
                ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                ret = -1;
                goto out;
        }

        /*
         * Request huge pages for about half of the free memory. The Kernel
         * will allocate as much as it can, and we expect it will get at least 1/3
         */
        nr_hugepages_ul = mem_free / hugepage_size / 2;
        snprintf(target_nr_hugepages, sizeof(target_nr_hugepages),
                 "%lu", nr_hugepages_ul);

        slen = strlen(target_nr_hugepages);
        if (write(fd, target_nr_hugepages, slen) != slen) {
                ksft_print_msg("Failed to write %lu to /proc/sys/vm/nr_hugepages: %s\n",
                               nr_hugepages_ul, strerror(errno));
                goto close_fd;
        }

        lseek(fd, 0, SEEK_SET);

        if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
                ksft_print_msg("Failed to re-read from /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                goto close_fd;
        }

        /* We should have been able to request at least 1/3 rd of the memory in
           huge pages */
        nr_hugepages_ul = strtoul(nr_hugepages, NULL, 10);
        if (!nr_hugepages_ul) {
                ksft_print_msg("ERROR: No memory is available as huge pages\n");
                goto close_fd;
        }
        compaction_index = mem_free/(nr_hugepages_ul * hugepage_size);

        lseek(fd, 0, SEEK_SET);

        if (write(fd, init_nr_hugepages, strlen(init_nr_hugepages))
            != strlen(init_nr_hugepages)) {
                ksft_print_msg("Failed to write value to /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                goto close_fd;
        }

        ksft_print_msg("Number of huge pages allocated = %lu\n",
                       nr_hugepages_ul);

        if (compaction_index > 3) {
                ksft_print_msg("ERROR: Less than 1/%d of memory is available\n"
                               "as huge pages\n", compaction_index);
                goto close_fd;
        }

        ret = 0;

 close_fd:
        close(fd);
 out:
        ksft_test_result(ret == 0, "check_compaction\n");
        return ret;
}

int set_zero_hugepages(unsigned long *initial_nr_hugepages)
{
        int fd, ret = -1;
        char nr_hugepages[20] = {0};

        fd = open("/proc/sys/vm/nr_hugepages", O_RDWR | O_NONBLOCK);
        if (fd < 0) {
                ksft_print_msg("Failed to open /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                goto out;
        }
        if (read(fd, nr_hugepages, sizeof(nr_hugepages)) <= 0) {
                ksft_print_msg("Failed to read from /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                goto close_fd;
        }

        lseek(fd, 0, SEEK_SET);

        /* Start with the initial condition of 0 huge pages */
        if (write(fd, "0", sizeof(char)) != sizeof(char)) {
                ksft_print_msg("Failed to write 0 to /proc/sys/vm/nr_hugepages: %s\n",
                               strerror(errno));
                goto close_fd;
        }

        *initial_nr_hugepages = strtoul(nr_hugepages, NULL, 10);
        ret = 0;

 close_fd:
        close(fd);

 out:
        return ret;
}

int main(int argc, char **argv)
{
        struct rlimit lim;
        struct map_list *list = NULL, *entry;
        size_t page_size, i;
        void *map = NULL;
        unsigned long mem_free = 0;
        unsigned long hugepage_size = 0;
        long mem_fragmentable_MB = 0;
        unsigned long initial_nr_hugepages;

        ksft_print_header();

        if (prereq() || geteuid())
                ksft_exit_skip("Prerequisites unsatisfied\n");

        ksft_set_plan(1);

        /* Start the test without hugepages reducing mem_free */
        if (set_zero_hugepages(&initial_nr_hugepages))
                ksft_exit_fail();

        lim.rlim_cur = RLIM_INFINITY;
        lim.rlim_max = RLIM_INFINITY;
        if (setrlimit(RLIMIT_MEMLOCK, &lim))
                ksft_exit_fail_msg("Failed to set rlimit: %s\n", strerror(errno));

        page_size = getpagesize();

        if (read_memory_info(&mem_free, &hugepage_size) != 0)
                ksft_exit_fail_msg("Failed to get meminfo\n");

        mem_fragmentable_MB = mem_free * 0.8 / 1024;

        while (mem_fragmentable_MB > 0) {
                map = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
                           MAP_ANONYMOUS | MAP_PRIVATE | MAP_LOCKED, -1, 0);
                if (map == MAP_FAILED)
                        break;

                entry = malloc(sizeof(struct map_list));
                if (!entry) {
                        munmap(map, MAP_SIZE);
                        break;
                }
                entry->map = map;
                entry->next = list;
                list = entry;

                /* Write something (in this case the address of the map) to
                 * ensure that KSM can't merge the mapped pages
                 */
                for (i = 0; i < MAP_SIZE; i += page_size)
                        *(unsigned long *)(map + i) = (unsigned long)map + i;

                mem_fragmentable_MB -= MAP_SIZE_MB;
        }

        for (entry = list; entry != NULL; entry = entry->next) {
                munmap(entry->map, MAP_SIZE);
                if (!entry->next)
                        break;
                entry = entry->next;
        }

        if (check_compaction(mem_free, hugepage_size,
                             initial_nr_hugepages) == 0)
                ksft_exit_pass();

        ksft_exit_fail();
}