diff options
Diffstat (limited to 'tools/testing/selftests/cgroup/test_zswap.c')
| -rw-r--r-- | tools/testing/selftests/cgroup/test_zswap.c | 635 |
1 files changed, 635 insertions, 0 deletions
diff --git a/tools/testing/selftests/cgroup/test_zswap.c b/tools/testing/selftests/cgroup/test_zswap.c new file mode 100644 index 000000000000..40de679248b8 --- /dev/null +++ b/tools/testing/selftests/cgroup/test_zswap.c @@ -0,0 +1,635 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include <linux/limits.h> +#include <unistd.h> +#include <stdio.h> +#include <signal.h> +#include <sys/sysinfo.h> +#include <string.h> +#include <sys/wait.h> +#include <sys/mman.h> + +#include "../kselftest.h" +#include "cgroup_util.h" + +static int read_int(const char *path, size_t *value) +{ + FILE *file; + int ret = 0; + + file = fopen(path, "r"); + if (!file) + return -1; + if (fscanf(file, "%ld", value) != 1) + ret = -1; + fclose(file); + return ret; +} + +static int set_min_free_kb(size_t value) +{ + FILE *file; + int ret; + + file = fopen("/proc/sys/vm/min_free_kbytes", "w"); + if (!file) + return -1; + ret = fprintf(file, "%ld\n", value); + fclose(file); + return ret; +} + +static int read_min_free_kb(size_t *value) +{ + return read_int("/proc/sys/vm/min_free_kbytes", value); +} + +static int get_zswap_stored_pages(size_t *value) +{ + return read_int("/sys/kernel/debug/zswap/stored_pages", value); +} + +static long get_cg_wb_count(const char *cg) +{ + return cg_read_key_long(cg, "memory.stat", "zswpwb"); +} + +static long get_zswpout(const char *cgroup) +{ + return cg_read_key_long(cgroup, "memory.stat", "zswpout "); +} + +static int allocate_and_read_bytes(const char *cgroup, void *arg) +{ + size_t size = (size_t)arg; + char *mem = (char *)malloc(size); + int ret = 0; + + if (!mem) + return -1; + for (int i = 0; i < size; i += 4095) + mem[i] = 'a'; + + /* Go through the allocated memory to (z)swap in and out pages */ + for (int i = 0; i < size; i += 4095) { + if (mem[i] != 'a') + ret = -1; + } + + free(mem); + return ret; +} + +static int allocate_bytes(const char *cgroup, void *arg) +{ + size_t size = (size_t)arg; + char *mem = (char *)malloc(size); + + if (!mem) + return -1; + for (int i = 0; i < size; i += 4095) + mem[i] = 'a'; + free(mem); + return 0; +} + +static char *setup_test_group_1M(const char *root, const char *name) +{ + char *group_name = cg_name(root, name); + + if (!group_name) + return NULL; + if (cg_create(group_name)) + goto fail; + if (cg_write(group_name, "memory.max", "1M")) { + cg_destroy(group_name); + goto fail; + } + return group_name; +fail: + free(group_name); + return NULL; +} + +/* + * Sanity test to check that pages are written into zswap. + */ +static int test_zswap_usage(const char *root) +{ + long zswpout_before, zswpout_after; + int ret = KSFT_FAIL; + char *test_group; + + test_group = cg_name(root, "no_shrink_test"); + if (!test_group) + goto out; + if (cg_create(test_group)) + goto out; + if (cg_write(test_group, "memory.max", "1M")) + goto out; + + zswpout_before = get_zswpout(test_group); + if (zswpout_before < 0) { + ksft_print_msg("Failed to get zswpout\n"); + goto out; + } + + /* Allocate more than memory.max to push memory into zswap */ + if (cg_run(test_group, allocate_bytes, (void *)MB(4))) + goto out; + + /* Verify that pages come into zswap */ + zswpout_after = get_zswpout(test_group); + if (zswpout_after <= zswpout_before) { + ksft_print_msg("zswpout does not increase after test program\n"); + goto out; + } + ret = KSFT_PASS; + +out: + cg_destroy(test_group); + free(test_group); + return ret; +} + +/* + * Check that when memory.zswap.max = 0, no pages can go to the zswap pool for + * the cgroup. + */ +static int test_swapin_nozswap(const char *root) +{ + int ret = KSFT_FAIL; + char *test_group; + long swap_peak, zswpout; + + test_group = cg_name(root, "no_zswap_test"); + if (!test_group) + goto out; + if (cg_create(test_group)) + goto out; + if (cg_write(test_group, "memory.max", "8M")) + goto out; + if (cg_write(test_group, "memory.zswap.max", "0")) + goto out; + + /* Allocate and read more than memory.max to trigger swapin */ + if (cg_run(test_group, allocate_and_read_bytes, (void *)MB(32))) + goto out; + + /* Verify that pages are swapped out, but no zswap happened */ + swap_peak = cg_read_long(test_group, "memory.swap.peak"); + if (swap_peak < 0) { + ksft_print_msg("failed to get cgroup's swap_peak\n"); + goto out; + } + + if (swap_peak < MB(24)) { + ksft_print_msg("at least 24MB of memory should be swapped out\n"); + goto out; + } + + zswpout = get_zswpout(test_group); + if (zswpout < 0) { + ksft_print_msg("failed to get zswpout\n"); + goto out; + } + + if (zswpout > 0) { + ksft_print_msg("zswapout > 0 when memory.zswap.max = 0\n"); + goto out; + } + + ret = KSFT_PASS; + +out: + cg_destroy(test_group); + free(test_group); + return ret; +} + +/* Simple test to verify the (z)swapin code paths */ +static int test_zswapin(const char *root) +{ + int ret = KSFT_FAIL; + char *test_group; + long zswpin; + + test_group = cg_name(root, "zswapin_test"); + if (!test_group) + goto out; + if (cg_create(test_group)) + goto out; + if (cg_write(test_group, "memory.max", "8M")) + goto out; + if (cg_write(test_group, "memory.zswap.max", "max")) + goto out; + + /* Allocate and read more than memory.max to trigger (z)swap in */ + if (cg_run(test_group, allocate_and_read_bytes, (void *)MB(32))) + goto out; + + zswpin = cg_read_key_long(test_group, "memory.stat", "zswpin "); + if (zswpin < 0) { + ksft_print_msg("failed to get zswpin\n"); + goto out; + } + + if (zswpin < MB(24) / PAGE_SIZE) { + ksft_print_msg("at least 24MB should be brought back from zswap\n"); + goto out; + } + + ret = KSFT_PASS; + +out: + cg_destroy(test_group); + free(test_group); + return ret; +} + +/* + * Attempt writeback with the following steps: + * 1. Allocate memory. + * 2. Reclaim memory equal to the amount that was allocated in step 1. + This will move it into zswap. + * 3. Save current zswap usage. + * 4. Move the memory allocated in step 1 back in from zswap. + * 5. Set zswap.max to half the amount that was recorded in step 3. + * 6. Attempt to reclaim memory equal to the amount that was allocated, + this will either trigger writeback if it's enabled, or reclamation + will fail if writeback is disabled as there isn't enough zswap space. + */ +static int attempt_writeback(const char *cgroup, void *arg) +{ + long pagesize = sysconf(_SC_PAGESIZE); + size_t memsize = MB(4); + char buf[pagesize]; + long zswap_usage; + bool wb_enabled = *(bool *) arg; + int ret = -1; + char *mem; + + mem = (char *)malloc(memsize); + if (!mem) + return ret; + + /* + * Fill half of each page with increasing data, and keep other + * half empty, this will result in data that is still compressible + * and ends up in zswap, with material zswap usage. + */ + for (int i = 0; i < pagesize; i++) + buf[i] = i < pagesize/2 ? (char) i : 0; + + for (int i = 0; i < memsize; i += pagesize) + memcpy(&mem[i], buf, pagesize); + + /* Try and reclaim allocated memory */ + if (cg_write_numeric(cgroup, "memory.reclaim", memsize)) { + ksft_print_msg("Failed to reclaim all of the requested memory\n"); + goto out; + } + + zswap_usage = cg_read_long(cgroup, "memory.zswap.current"); + + /* zswpin */ + for (int i = 0; i < memsize; i += pagesize) { + if (memcmp(&mem[i], buf, pagesize)) { + ksft_print_msg("invalid memory\n"); + goto out; + } + } + + if (cg_write_numeric(cgroup, "memory.zswap.max", zswap_usage/2)) + goto out; + + /* + * If writeback is enabled, trying to reclaim memory now will trigger a + * writeback as zswap.max is half of what was needed when reclaim ran the first time. + * If writeback is disabled, memory reclaim will fail as zswap is limited and + * it can't writeback to swap. + */ + ret = cg_write_numeric(cgroup, "memory.reclaim", memsize); + if (!wb_enabled) + ret = (ret == -EAGAIN) ? 0 : -1; + +out: + free(mem); + return ret; +} + +static int test_zswap_writeback_one(const char *cgroup, bool wb) +{ + long zswpwb_before, zswpwb_after; + + zswpwb_before = get_cg_wb_count(cgroup); + if (zswpwb_before != 0) { + ksft_print_msg("zswpwb_before = %ld instead of 0\n", zswpwb_before); + return -1; + } + + if (cg_run(cgroup, attempt_writeback, (void *) &wb)) + return -1; + + /* Verify that zswap writeback occurred only if writeback was enabled */ + zswpwb_after = get_cg_wb_count(cgroup); + if (zswpwb_after < 0) + return -1; + + if (wb != !!zswpwb_after) { + ksft_print_msg("zswpwb_after is %ld while wb is %s", + zswpwb_after, wb ? "enabled" : "disabled"); + return -1; + } + + return 0; +} + +/* Test to verify the zswap writeback path */ +static int test_zswap_writeback(const char *root, bool wb) +{ + int ret = KSFT_FAIL; + char *test_group, *test_group_child = NULL; + + if (cg_read_strcmp(root, "memory.zswap.writeback", "1")) + return KSFT_SKIP; + + test_group = cg_name(root, "zswap_writeback_test"); + if (!test_group) + goto out; + if (cg_create(test_group)) + goto out; + if (cg_write(test_group, "memory.zswap.writeback", wb ? "1" : "0")) + goto out; + + if (test_zswap_writeback_one(test_group, wb)) + goto out; + + /* Reset memory.zswap.max to max (modified by attempt_writeback), and + * set up child cgroup, whose memory.zswap.writeback is hardcoded to 1. + * Thus, the parent's setting shall be what's in effect. */ + if (cg_write(test_group, "memory.zswap.max", "max")) + goto out; + if (cg_write(test_group, "cgroup.subtree_control", "+memory")) + goto out; + + test_group_child = cg_name(test_group, "zswap_writeback_test_child"); + if (!test_group_child) + goto out; + if (cg_create(test_group_child)) + goto out; + if (cg_write(test_group_child, "memory.zswap.writeback", "1")) + goto out; + + if (test_zswap_writeback_one(test_group_child, wb)) + goto out; + + ret = KSFT_PASS; + +out: + if (test_group_child) { + cg_destroy(test_group_child); + free(test_group_child); + } + cg_destroy(test_group); + free(test_group); + return ret; +} + +static int test_zswap_writeback_enabled(const char *root) +{ + return test_zswap_writeback(root, true); +} + +static int test_zswap_writeback_disabled(const char *root) +{ + return test_zswap_writeback(root, false); +} + +/* + * When trying to store a memcg page in zswap, if the memcg hits its memory + * limit in zswap, writeback should affect only the zswapped pages of that + * memcg. + */ +static int test_no_invasive_cgroup_shrink(const char *root) +{ + int ret = KSFT_FAIL; + size_t control_allocation_size = MB(10); + char *control_allocation = NULL, *wb_group = NULL, *control_group = NULL; + + wb_group = setup_test_group_1M(root, "per_memcg_wb_test1"); + if (!wb_group) + return KSFT_FAIL; + if (cg_write(wb_group, "memory.zswap.max", "10K")) + goto out; + control_group = setup_test_group_1M(root, "per_memcg_wb_test2"); + if (!control_group) + goto out; + + /* Push some test_group2 memory into zswap */ + if (cg_enter_current(control_group)) + goto out; + control_allocation = malloc(control_allocation_size); + for (int i = 0; i < control_allocation_size; i += 4095) + control_allocation[i] = 'a'; + if (cg_read_key_long(control_group, "memory.stat", "zswapped") < 1) + goto out; + + /* Allocate 10x memory.max to push wb_group memory into zswap and trigger wb */ + if (cg_run(wb_group, allocate_bytes, (void *)MB(10))) + goto out; + + /* Verify that only zswapped memory from gwb_group has been written back */ + if (get_cg_wb_count(wb_group) > 0 && get_cg_wb_count(control_group) == 0) + ret = KSFT_PASS; +out: + cg_enter_current(root); + if (control_group) { + cg_destroy(control_group); + free(control_group); + } + cg_destroy(wb_group); + free(wb_group); + if (control_allocation) + free(control_allocation); + return ret; +} + +struct no_kmem_bypass_child_args { + size_t target_alloc_bytes; + size_t child_allocated; +}; + +static int no_kmem_bypass_child(const char *cgroup, void *arg) +{ + struct no_kmem_bypass_child_args *values = arg; + void *allocation; + + allocation = malloc(values->target_alloc_bytes); + if (!allocation) { + values->child_allocated = true; + return -1; + } + for (long i = 0; i < values->target_alloc_bytes; i += 4095) + ((char *)allocation)[i] = 'a'; + values->child_allocated = true; + pause(); + free(allocation); + return 0; +} + +/* + * When pages owned by a memcg are pushed to zswap by kswapd, they should be + * charged to that cgroup. This wasn't the case before commit + * cd08d80ecdac("mm: correctly charge compressed memory to its memcg"). + * + * The test first allocates memory in a memcg, then raises min_free_kbytes to + * a very high value so that the allocation falls below low wm, then makes + * another allocation to trigger kswapd that should push the memcg-owned pages + * to zswap and verifies that the zswap pages are correctly charged. + * + * To be run on a VM with at most 4G of memory. + */ +static int test_no_kmem_bypass(const char *root) +{ + size_t min_free_kb_high, min_free_kb_low, min_free_kb_original; + struct no_kmem_bypass_child_args *values; + size_t trigger_allocation_size; + int wait_child_iteration = 0; + long stored_pages_threshold; + struct sysinfo sys_info; + int ret = KSFT_FAIL; + int child_status; + char *test_group = NULL; + pid_t child_pid; + + /* Read sys info and compute test values accordingly */ + if (sysinfo(&sys_info) != 0) + return KSFT_FAIL; + if (sys_info.totalram > 5000000000) + return KSFT_SKIP; + values = mmap(0, sizeof(struct no_kmem_bypass_child_args), PROT_READ | + PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); + if (values == MAP_FAILED) + return KSFT_FAIL; + if (read_min_free_kb(&min_free_kb_original)) + return KSFT_FAIL; + min_free_kb_high = sys_info.totalram / 2000; + min_free_kb_low = sys_info.totalram / 500000; + values->target_alloc_bytes = (sys_info.totalram - min_free_kb_high * 1000) + + sys_info.totalram * 5 / 100; + stored_pages_threshold = sys_info.totalram / 5 / 4096; + trigger_allocation_size = sys_info.totalram / 20; + + /* Set up test memcg */ + test_group = cg_name(root, "kmem_bypass_test"); + if (!test_group) + goto out; + + /* Spawn memcg child and wait for it to allocate */ + set_min_free_kb(min_free_kb_low); + if (cg_create(test_group)) + goto out; + values->child_allocated = false; + child_pid = cg_run_nowait(test_group, no_kmem_bypass_child, values); + if (child_pid < 0) + goto out; + while (!values->child_allocated && wait_child_iteration++ < 10000) + usleep(1000); + + /* Try to wakeup kswapd and let it push child memory to zswap */ + set_min_free_kb(min_free_kb_high); + for (int i = 0; i < 20; i++) { + size_t stored_pages; + char *trigger_allocation = malloc(trigger_allocation_size); + + if (!trigger_allocation) + break; + for (int i = 0; i < trigger_allocation_size; i += 4095) + trigger_allocation[i] = 'b'; + usleep(100000); + free(trigger_allocation); + if (get_zswap_stored_pages(&stored_pages)) + break; + if (stored_pages < 0) + break; + /* If memory was pushed to zswap, verify it belongs to memcg */ + if (stored_pages > stored_pages_threshold) { + int zswapped = cg_read_key_long(test_group, "memory.stat", "zswapped "); + int delta = stored_pages * 4096 - zswapped; + int result_ok = delta < stored_pages * 4096 / 4; + + ret = result_ok ? KSFT_PASS : KSFT_FAIL; + break; + } + } + + kill(child_pid, SIGTERM); + waitpid(child_pid, &child_status, 0); +out: + set_min_free_kb(min_free_kb_original); + cg_destroy(test_group); + free(test_group); + return ret; +} + +#define T(x) { x, #x } +struct zswap_test { + int (*fn)(const char *root); + const char *name; +} tests[] = { + T(test_zswap_usage), + T(test_swapin_nozswap), + T(test_zswapin), + T(test_zswap_writeback_enabled), + T(test_zswap_writeback_disabled), + T(test_no_kmem_bypass), + T(test_no_invasive_cgroup_shrink), +}; +#undef T + +static bool zswap_configured(void) +{ + return access("/sys/module/zswap", F_OK) == 0; +} + +int main(int argc, char **argv) +{ + char root[PATH_MAX]; + int i, ret = EXIT_SUCCESS; + + if (cg_find_unified_root(root, sizeof(root), NULL)) + ksft_exit_skip("cgroup v2 isn't mounted\n"); + + if (!zswap_configured()) + ksft_exit_skip("zswap isn't configured\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: + ret = EXIT_FAILURE; + ksft_test_result_fail("%s\n", tests[i].name); + break; + } + } + + return ret; +} |