// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE

#include <linux/limits.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <errno.h>
#include <sys/sysinfo.h>
#include <pthread.h>

#include "kselftest.h"
#include "cgroup_util.h"


/*
 * Memory cgroup charging is performed using percpu batches 64 pages
 * big (look at MEMCG_CHARGE_BATCH), whereas memory.stat is exact. So
 * the maximum discrepancy between charge and vmstat entries is number
 * of cpus multiplied by 64 pages.
 */
#define MAX_VMSTAT_ERROR (4096 * 64 * get_nprocs())

#define KMEM_DEAD_WAIT_RETRIES        80

static int alloc_dcache(const char *cgroup, void *arg)
{
        unsigned long i;
        struct stat st;
        char buf[128];

        for (i = 0; i < (unsigned long)arg; i++) {
                snprintf(buf, sizeof(buf),
                        "/something-non-existent-with-a-long-name-%64lu-%d",
                         i, getpid());
                stat(buf, &st);
        }

        return 0;
}

/*
 * This test allocates 100000 of negative dentries with long names.
 * Then it checks that "slab" in memory.stat is larger than 1M.
 * Then it sets memory.high to 1M and checks that at least 1/2
 * of slab memory has been reclaimed.
 */
static int test_kmem_basic(const char *root)
{
        int ret = KSFT_FAIL;
        char *cg = NULL;
        long slab0, slab1, current;

        cg = cg_name(root, "kmem_basic_test");
        if (!cg)
                goto cleanup;

        if (cg_create(cg))
                goto cleanup;

        if (cg_run(cg, alloc_dcache, (void *)100000))
                goto cleanup;

        slab0 = cg_read_key_long(cg, "memory.stat", "slab ");
        if (slab0 < (1 << 20))
                goto cleanup;

        cg_write(cg, "memory.high", "1M");

        /* wait for RCU freeing */
        sleep(1);

        slab1 = cg_read_key_long(cg, "memory.stat", "slab ");
        if (slab1 < 0)
                goto cleanup;

        current = cg_read_long(cg, "memory.current");
        if (current < 0)
                goto cleanup;

        if (slab1 < slab0 / 2 && current < slab0 / 2)
                ret = KSFT_PASS;
cleanup:
        cg_destroy(cg);
        free(cg);

        return ret;
}

static void *alloc_kmem_fn(void *arg)
{
        alloc_dcache(NULL, (void *)100);
        return NULL;
}

static int alloc_kmem_smp(const char *cgroup, void *arg)
{
        int nr_threads = 2 * get_nprocs();
        pthread_t *tinfo;
        unsigned long i;
        int ret = -1;

        tinfo = calloc(nr_threads, sizeof(pthread_t));
        if (tinfo == NULL)
                return -1;

        for (i = 0; i < nr_threads; i++) {
                if (pthread_create(&tinfo[i], NULL, &alloc_kmem_fn,
                                   (void *)i)) {
                        free(tinfo);
                        return -1;
                }
        }

        for (i = 0; i < nr_threads; i++) {
                ret = pthread_join(tinfo[i], NULL);
                if (ret)
                        break;
        }

        free(tinfo);
        return ret;
}

static int cg_run_in_subcgroups(const char *parent,
                                int (*fn)(const char *cgroup, void *arg),
                                void *arg, int times)
{
        char *child;
        int i;

        for (i = 0; i < times; i++) {
                child = cg_name_indexed(parent, "child", i);
                if (!child)
                        return -1;

                if (cg_create(child)) {
                        cg_destroy(child);
                        free(child);
                        return -1;
                }

                if (cg_run(child, fn, NULL)) {
                        cg_destroy(child);
                        free(child);
                        return -1;
                }

                cg_destroy(child);
                free(child);
        }

        return 0;
}

/*
 * The test creates and destroys a large number of cgroups. In each cgroup it
 * allocates some slab memory (mostly negative dentries) using 2 * NR_CPUS
 * threads. Then it checks the sanity of numbers on the parent level:
 * the total size of the cgroups should be roughly equal to
 * anon + file + kernel + sock.
 */
static int test_kmem_memcg_deletion(const char *root)
{
        long current, anon, file, kernel, sock, sum;
        int ret = KSFT_FAIL;
        char *parent;

        parent = cg_name(root, "kmem_memcg_deletion_test");
        if (!parent)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_write(parent, "cgroup.subtree_control", "+memory"))
                goto cleanup;

        if (cg_run_in_subcgroups(parent, alloc_kmem_smp, NULL, 100))
                goto cleanup;

        current = cg_read_long(parent, "memory.current");
        anon = cg_read_key_long(parent, "memory.stat", "anon ");
        file = cg_read_key_long(parent, "memory.stat", "file ");
        kernel = cg_read_key_long(parent, "memory.stat", "kernel ");
        sock = cg_read_key_long(parent, "memory.stat", "sock ");
        if (current < 0 || anon < 0 || file < 0 || kernel < 0 || sock < 0)
                goto cleanup;

        sum = anon + file + kernel + sock;
        if (labs(sum - current) < MAX_VMSTAT_ERROR) {
                ret = KSFT_PASS;
        } else {
                printf("memory.current = %ld\n", current);
                printf("anon + file + kernel + sock = %ld\n", sum);
                printf("anon = %ld\n", anon);
                printf("file = %ld\n", file);
                printf("kernel = %ld\n", kernel);
                printf("sock = %ld\n", sock);
        }

cleanup:
        cg_destroy(parent);
        free(parent);

        return ret;
}

/*
 * The test reads the entire /proc/kpagecgroup. If the operation went
 * successfully (and the kernel didn't panic), the test is treated as passed.
 */
static int test_kmem_proc_kpagecgroup(const char *root)
{
        unsigned long buf[128];
        int ret = KSFT_FAIL;
        ssize_t len;
        int fd;

        fd = open("/proc/kpagecgroup", O_RDONLY);
        if (fd < 0)
                return ret;

        do {
                len = read(fd, buf, sizeof(buf));
        } while (len > 0);

        if (len == 0)
                ret = KSFT_PASS;

        close(fd);
        return ret;
}

static void *pthread_wait_fn(void *arg)
{
        sleep(100);
        return NULL;
}

static int spawn_1000_threads(const char *cgroup, void *arg)
{
        int nr_threads = 1000;
        pthread_t *tinfo;
        unsigned long i;
        long stack;
        int ret = -1;

        tinfo = calloc(nr_threads, sizeof(pthread_t));
        if (tinfo == NULL)
                return -1;

        for (i = 0; i < nr_threads; i++) {
                if (pthread_create(&tinfo[i], NULL, &pthread_wait_fn,
                                   (void *)i)) {
                        free(tinfo);
                        return(-1);
                }
        }

        stack = cg_read_key_long(cgroup, "memory.stat", "kernel_stack ");
        if (stack >= 4096 * 1000)
                ret = 0;

        free(tinfo);
        return ret;
}

/*
 * The test spawns a process, which spawns 1000 threads. Then it checks
 * that memory.stat's kernel_stack is at least 1000 pages large.
 */
static int test_kmem_kernel_stacks(const char *root)
{
        int ret = KSFT_FAIL;
        char *cg = NULL;

        cg = cg_name(root, "kmem_kernel_stacks_test");
        if (!cg)
                goto cleanup;

        if (cg_create(cg))
                goto cleanup;

        if (cg_run(cg, spawn_1000_threads, NULL))
                goto cleanup;

        ret = KSFT_PASS;
cleanup:
        cg_destroy(cg);
        free(cg);

        return ret;
}

/*
 * This test sequentionally creates 30 child cgroups, allocates some
 * kernel memory in each of them, and deletes them. Then it checks
 * that the number of dying cgroups on the parent level is 0.
 */
static int test_kmem_dead_cgroups(const char *root)
{
        int ret = KSFT_FAIL;
        char *parent;
        long dead = -1;

        parent = cg_name(root, "kmem_dead_cgroups_test");
        if (!parent)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_write(parent, "cgroup.subtree_control", "+memory"))
                goto cleanup;

        if (cg_run_in_subcgroups(parent, alloc_dcache, (void *)100, 30))
                goto cleanup;

        /*
         * Allow up to ~8s for reclaim of dying descendants to complete.
         * This is a generous upper bound derived from stress testing, not
         * from a specific kernel constant, and can be adjusted if reclaim
         * behavior changes in the future.
         */
        dead = cg_read_key_long_poll(parent, "cgroup.stat",
                                        "nr_dying_descendants ", 0, KMEM_DEAD_WAIT_RETRIES,
                                        DEFAULT_WAIT_INTERVAL_US);
        if (dead)
                goto cleanup;

        ret = KSFT_PASS;

cleanup:
        cg_destroy(parent);
        free(parent);

        return ret;
}

/*
 * This test creates a sub-tree with 1000 memory cgroups.
 * Then it checks that the memory.current on the parent level
 * is greater than 0 and approximates matches the percpu value
 * from memory.stat.
 */
static int test_percpu_basic(const char *root)
{
        int ret = KSFT_FAIL;
        char *parent, *child;
        long current, percpu;
        int i;

        parent = cg_name(root, "percpu_basic_test");
        if (!parent)
                goto cleanup;

        if (cg_create(parent))
                goto cleanup;

        if (cg_write(parent, "cgroup.subtree_control", "+memory"))
                goto cleanup;

        for (i = 0; i < 1000; i++) {
                child = cg_name_indexed(parent, "child", i);
                if (!child)
                        return -1;

                if (cg_create(child))
                        goto cleanup_children;

                free(child);
        }

        current = cg_read_long(parent, "memory.current");
        percpu = cg_read_key_long(parent, "memory.stat", "percpu ");

        if (current > 0 && percpu > 0 && labs(current - percpu) <
            MAX_VMSTAT_ERROR)
                ret = KSFT_PASS;
        else
                printf("memory.current %ld\npercpu %ld\n",
                       current, percpu);

cleanup_children:
        for (i = 0; i < 1000; i++) {
                child = cg_name_indexed(parent, "child", i);
                cg_destroy(child);
                free(child);
        }

cleanup:
        cg_destroy(parent);
        free(parent);

        return ret;
}

#define T(x) { x, #x }
struct kmem_test {
        int (*fn)(const char *root);
        const char *name;
} tests[] = {
        T(test_kmem_basic),
        T(test_kmem_memcg_deletion),
        T(test_kmem_proc_kpagecgroup),
        T(test_kmem_kernel_stacks),
        T(test_kmem_dead_cgroups),
        T(test_percpu_basic),
};
#undef T

int main(int argc, char **argv)
{
        char root[PATH_MAX];
        int i;

        ksft_print_header();
        ksft_set_plan(ARRAY_SIZE(tests));
        if (cg_find_unified_root(root, sizeof(root), NULL))
                ksft_exit_skip("cgroup v2 isn't mounted\n");

        /*
         * Check that memory controller is available:
         * memory is listed in cgroup.controllers
         */
        if (cg_read_strstr(root, "cgroup.controllers", "memory"))
                ksft_exit_skip("memory controller isn't available\n");

        if (cg_read_strstr(root, "cgroup.subtree_control", "memory"))
                if (cg_write(root, "cgroup.subtree_control", "+memory"))
                        ksft_exit_skip("Failed to set memory controller\n");

        for (i = 0; i < ARRAY_SIZE(tests); i++) {
                switch (tests[i].fn(root)) {
                case KSFT_PASS:
                        ksft_test_result_pass("%s\n", tests[i].name);
                        break;
                case KSFT_SKIP:
                        ksft_test_result_skip("%s\n", tests[i].name);
                        break;
                default:
                        ksft_test_result_fail("%s\n", tests[i].name);
                        break;
                }
        }

        ksft_finished();
}