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Systemd/src/oom/oomd-manager.c

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/* SPDX-License-Identifier: LGPL-2.1+ */
#include "bus-log-control-api.h"
#include "bus-util.h"
#include "bus-polkit.h"
#include "cgroup-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "oomd-manager-bus.h"
#include "oomd-manager.h"
#include "path-util.h"
typedef struct ManagedOOMReply {
ManagedOOMMode mode;
char *path;
char *property;
unsigned limit;
} ManagedOOMReply;
static void managed_oom_reply_destroy(ManagedOOMReply *reply) {
assert(reply);
free(reply->path);
free(reply->property);
}
static int managed_oom_mode(const char *name, JsonVariant *v, JsonDispatchFlags flags, void *userdata) {
ManagedOOMMode *mode = userdata, m;
const char *s;
assert(mode);
assert_se(s = json_variant_string(v));
m = managed_oom_mode_from_string(s);
if (m < 0)
return json_log(v, flags, SYNTHETIC_ERRNO(EINVAL), "%s is not a valid ManagedOOMMode", s);
*mode = m;
return 0;
}
static int process_managed_oom_reply(
Varlink *link,
JsonVariant *parameters,
const char *error_id,
VarlinkReplyFlags flags,
void *userdata) {
JsonVariant *c, *cgroups;
Manager *m = userdata;
int r = 0;
assert(m);
static const JsonDispatch dispatch_table[] = {
{ "mode", JSON_VARIANT_STRING, managed_oom_mode, offsetof(ManagedOOMReply, mode), JSON_MANDATORY },
{ "path", JSON_VARIANT_STRING, json_dispatch_string, offsetof(ManagedOOMReply, path), JSON_MANDATORY },
{ "property", JSON_VARIANT_STRING, json_dispatch_string, offsetof(ManagedOOMReply, property), JSON_MANDATORY },
{ "limit", JSON_VARIANT_UNSIGNED, json_dispatch_unsigned, offsetof(ManagedOOMReply, limit), 0 },
{},
};
if (error_id) {
r = -EIO;
log_debug("Error getting ManagedOOM cgroups: %s", error_id);
goto finish;
}
cgroups = json_variant_by_key(parameters, "cgroups");
if (!cgroups) {
r = -EINVAL;
goto finish;
}
/* Skip malformed elements and keep processing in case the others are good */
JSON_VARIANT_ARRAY_FOREACH(c, cgroups) {
_cleanup_(managed_oom_reply_destroy) ManagedOOMReply reply = {};
OomdCGroupContext *ctx;
Hashmap *monitor_hm;
loadavg_t limit;
int ret;
if (!json_variant_is_object(c))
continue;
ret = json_dispatch(c, dispatch_table, NULL, 0, &reply);
if (ret == -ENOMEM) {
r = ret;
goto finish;
} else if (ret < 0)
continue;
monitor_hm = streq(reply.property, "ManagedOOMSwap") ?
m->monitored_swap_cgroup_contexts : m->monitored_mem_pressure_cgroup_contexts;
if (reply.mode == MANAGED_OOM_AUTO) {
(void) oomd_cgroup_context_free(hashmap_remove(monitor_hm, reply.path));
continue;
}
limit = m->default_mem_pressure_limit;
if (streq(reply.property, "ManagedOOMMemoryPressure")) {
if (reply.limit > 100)
continue;
else if (reply.limit != 0) {
ret = store_loadavg_fixed_point((unsigned long) reply.limit, 0, &limit);
if (ret < 0)
continue;
}
}
ret = oomd_insert_cgroup_context(NULL, monitor_hm, reply.path);
if (ret == -ENOMEM) {
r = ret;
goto finish;
}
/* Always update the limit in case it was changed. For non-memory pressure detection the value is
* ignored so always updating it here is not a problem. */
ctx = hashmap_get(monitor_hm, reply.path);
if (ctx)
ctx->mem_pressure_limit = limit;
}
finish:
if (!FLAGS_SET(flags, VARLINK_REPLY_CONTINUES))
m->varlink = varlink_close_unref(link);
return r;
}
/* Fill `new_h` with `path`'s descendent OomdCGroupContexts. Only include descendent cgroups that are possible
* candidates for action. That is, only leaf cgroups or cgroups with memory.oom.group set to "1".
*
* This function ignores most errors in order to handle cgroups that may have been cleaned up while populating
* the hashmap.
*
* `new_h` is of the form { key: cgroup paths -> value: OomdCGroupContext } */
static int recursively_get_cgroup_context(Hashmap *new_h, const char *path) {
_cleanup_free_ char *subpath = NULL;
_cleanup_closedir_ DIR *d = NULL;
int r;
assert(new_h);
assert(path);
r = cg_enumerate_subgroups(SYSTEMD_CGROUP_CONTROLLER, path, &d);
if (r < 0)
return r;
r = cg_read_subgroup(d, &subpath);
if (r < 0)
return r;
else if (r == 0) { /* No subgroups? We're a leaf node */
r = oomd_insert_cgroup_context(NULL, new_h, path);
return (r == -ENOMEM) ? r : 0;
}
do {
_cleanup_free_ char *cg_path = NULL;
bool oom_group;
cg_path = path_join(empty_to_root(path), subpath);
if (!cg_path)
return -ENOMEM;
subpath = mfree(subpath);
r = cg_get_attribute_as_bool("memory", cg_path, "memory.oom.group", &oom_group);
/* The cgroup might be gone. Skip it as a candidate since we can't get information on it. */
if (r < 0)
return (r == -ENOMEM) ? r : 0;
if (oom_group) {
r = oomd_insert_cgroup_context(NULL, new_h, cg_path);
if (r == -ENOMEM)
return r;
} else {
r = recursively_get_cgroup_context(new_h, cg_path);
if (r == -ENOMEM)
return r;
}
} while ((r = cg_read_subgroup(d, &subpath)) > 0);
return 0;
}
static int update_monitored_cgroup_contexts(Hashmap **monitored_cgroups) {
_cleanup_hashmap_free_ Hashmap *new_base = NULL;
OomdCGroupContext *ctx;
int r;
assert(monitored_cgroups);
new_base = hashmap_new(&oomd_cgroup_ctx_hash_ops);
if (!new_base)
return -ENOMEM;
HASHMAP_FOREACH(ctx, *monitored_cgroups) {
/* Skip most errors since the cgroup we're trying to update might not exist anymore. */
r = oomd_insert_cgroup_context(*monitored_cgroups, new_base, ctx->path);
if (r == -ENOMEM)
return r;
}
hashmap_free(*monitored_cgroups);
*monitored_cgroups = TAKE_PTR(new_base);
return 0;
}
static int get_monitored_cgroup_contexts_candidates(Hashmap *monitored_cgroups, Hashmap **ret_candidates) {
_cleanup_hashmap_free_ Hashmap *candidates = NULL;
OomdCGroupContext *ctx;
int r;
assert(monitored_cgroups);
assert(ret_candidates);
candidates = hashmap_new(&oomd_cgroup_ctx_hash_ops);
if (!candidates)
return -ENOMEM;
HASHMAP_FOREACH(ctx, monitored_cgroups) {
r = recursively_get_cgroup_context(candidates, ctx->path);
if (r == -ENOMEM)
return r;
}
*ret_candidates = TAKE_PTR(candidates);
return 0;
}
static int acquire_managed_oom_connect(Manager *m) {
_cleanup_(varlink_close_unrefp) Varlink *link = NULL;
int r;
assert(m);
assert(m->event);
r = varlink_connect_address(&link, VARLINK_ADDR_PATH_MANAGED_OOM);
if (r < 0)
return log_error_errno(r, "Failed to connect to %s: %m", VARLINK_ADDR_PATH_MANAGED_OOM);
(void) varlink_set_userdata(link, m);
(void) varlink_set_description(link, "oomd");
(void) varlink_set_relative_timeout(link, USEC_INFINITY);
r = varlink_attach_event(link, m->event, SD_EVENT_PRIORITY_NORMAL);
if (r < 0)
return log_error_errno(r, "Failed to attach varlink connection to event loop: %m");
r = varlink_bind_reply(link, process_managed_oom_reply);
if (r < 0)
return log_error_errno(r, "Failed to bind reply callback: %m");
r = varlink_observe(link, "io.systemd.ManagedOOM.SubscribeManagedOOMCGroups", NULL);
if (r < 0)
return log_error_errno(r, "Failed to observe varlink call: %m");
m->varlink = TAKE_PTR(link);
return 0;
}
static int monitor_cgroup_contexts_handler(sd_event_source *s, uint64_t usec, void *userdata) {
_cleanup_set_free_ Set *targets = NULL;
Manager *m = userdata;
usec_t usec_now;
int r;
assert(s);
assert(userdata);
/* Reset timer */
r = sd_event_now(sd_event_source_get_event(s), CLOCK_MONOTONIC, &usec_now);
if (r < 0)
return log_error_errno(r, "Failed to reset event timer");
r = sd_event_source_set_time_relative(s, INTERVAL_USEC);
if (r < 0)
return log_error_errno(r, "Failed to set relative time for timer");
/* Reconnect if our connection dropped */
if (!m->varlink) {
r = acquire_managed_oom_connect(m);
if (r < 0)
return log_error_errno(r, "Failed to acquire varlink connection");
}
/* Update the cgroups used for detection/action */
r = update_monitored_cgroup_contexts(&m->monitored_swap_cgroup_contexts);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to update monitored swap cgroup contexts");
r = update_monitored_cgroup_contexts(&m->monitored_mem_pressure_cgroup_contexts);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to update monitored memory pressure cgroup contexts");
r = oomd_system_context_acquire("/proc/swaps", &m->system_context);
/* If there aren't units depending on swap actions, the only error we exit on is ENOMEM */
if (r == -ENOMEM || (r < 0 && !hashmap_isempty(m->monitored_swap_cgroup_contexts)))
return log_error_errno(r, "Failed to acquire system context");
/* If we're still recovering from a kill, don't try to kill again yet */
if (m->post_action_delay_start > 0) {
if (m->post_action_delay_start + POST_ACTION_DELAY_USEC > usec_now)
return 0;
else
m->post_action_delay_start = 0;
}
r = oomd_pressure_above(m->monitored_mem_pressure_cgroup_contexts, PRESSURE_DURATION_USEC, &targets);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to check if memory pressure exceeded limits");
else if (r == 1) {
/* Check if there was reclaim activity in the last interval. The concern is the following case:
* Pressure climbed, a lot of high-frequency pages were reclaimed, and we killed the offending
* cgroup. Even after this, well-behaved processes will fault in recently resident pages and
* this will cause pressure to remain high. Thus if there isn't any reclaim pressure, no need
* to kill something (it won't help anyways). */
if (oomd_memory_reclaim(m->monitored_mem_pressure_cgroup_contexts)) {
_cleanup_hashmap_free_ Hashmap *candidates = NULL;
OomdCGroupContext *t;
r = get_monitored_cgroup_contexts_candidates(m->monitored_mem_pressure_cgroup_contexts, &candidates);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to get monitored memory pressure cgroup candidates");
SET_FOREACH(t, targets) {
log_notice("Memory pressure for %s is greater than %lu for more than %"PRIu64" seconds and there was reclaim activity",
t->path, LOAD_INT(t->mem_pressure_limit), PRESSURE_DURATION_USEC / USEC_PER_SEC);
r = oomd_kill_by_pgscan(candidates, t->path, m->dry_run);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to kill cgroup processes by pgscan");
if (r < 0)
log_info("Failed to kill any cgroup(s) under %s based on pressure", t->path);
else {
/* Don't act on all the high pressure cgroups at once; return as soon as we kill one */
m->post_action_delay_start = usec_now;
return 0;
}
}
}
}
if (oomd_swap_free_below(&m->system_context, (100 - m->swap_used_limit))) {
_cleanup_hashmap_free_ Hashmap *candidates = NULL;
log_notice("Swap used (%"PRIu64") / total (%"PRIu64") is more than %u%%",
m->system_context.swap_used, m->system_context.swap_total, m->swap_used_limit);
r = get_monitored_cgroup_contexts_candidates(m->monitored_swap_cgroup_contexts, &candidates);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to get monitored swap cgroup candidates");
r = oomd_kill_by_swap_usage(candidates, m->dry_run);
if (r == -ENOMEM)
return log_error_errno(r, "Failed to kill cgroup processes by swap usage");
if (r < 0)
log_info("Failed to kill any cgroup(s) based on swap");
else {
m->post_action_delay_start = usec_now;
return 0;
}
}
return 0;
}
static int monitor_cgroup_contexts(Manager *m) {
_cleanup_(sd_event_source_unrefp) sd_event_source *s = NULL;
int r;
assert(m);
assert(m->event);
r = sd_event_add_time(m->event, &s, CLOCK_MONOTONIC, 0, 0, monitor_cgroup_contexts_handler, m);
if (r < 0)
return r;
r = sd_event_source_set_exit_on_failure(s, true);
if (r < 0)
return r;
r = sd_event_source_set_enabled(s, SD_EVENT_ON);
if (r < 0)
return r;
(void) sd_event_source_set_description(s, "oomd-timer");
m->cgroup_context_event_source = TAKE_PTR(s);
return 0;
}
void manager_free(Manager *m) {
assert(m);
varlink_close_unref(m->varlink);
sd_event_source_unref(m->cgroup_context_event_source);
sd_event_unref(m->event);
bus_verify_polkit_async_registry_free(m->polkit_registry);
sd_bus_flush_close_unref(m->bus);
hashmap_free(m->monitored_swap_cgroup_contexts);
hashmap_free(m->monitored_mem_pressure_cgroup_contexts);
free(m);
}
int manager_new(Manager **ret) {
_cleanup_(manager_freep) Manager *m = NULL;
int r;
assert(ret);
m = new0(Manager, 1);
if (!m)
return -ENOMEM;
r = sd_event_default(&m->event);
if (r < 0)
return r;
(void) sd_event_set_watchdog(m->event, true);
r = sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
if (r < 0)
return r;
r = sd_event_add_signal(m->event, NULL, SIGTERM, NULL, NULL);
if (r < 0)
return r;
m->monitored_swap_cgroup_contexts = hashmap_new(&oomd_cgroup_ctx_hash_ops);
if (!m->monitored_swap_cgroup_contexts)
return -ENOMEM;
m->monitored_mem_pressure_cgroup_contexts = hashmap_new(&oomd_cgroup_ctx_hash_ops);
if (!m->monitored_mem_pressure_cgroup_contexts)
return -ENOMEM;
*ret = TAKE_PTR(m);
return 0;
}
static int manager_connect_bus(Manager *m) {
int r;
assert(m);
assert(!m->bus);
r = bus_open_system_watch_bind_with_description(&m->bus, "bus-api-oom");
if (r < 0)
return log_error_errno(r, "Failed to connect to bus: %m");
r = sd_bus_add_object_vtable(m->bus, NULL, "/org/freedesktop/oom1", "org.freedesktop.oom1.Manager", manager_vtable, m);
if (r < 0)
return log_error_errno(r, "Failed to add manager object vtable: %m");
r = bus_log_control_api_register(m->bus);
if (r < 0)
return r;
r = sd_bus_request_name_async(m->bus, NULL, "org.freedesktop.oom1", 0, NULL, NULL);
if (r < 0)
return log_error_errno(r, "Failed to request name: %m");
r = sd_bus_attach_event(m->bus, m->event, 0);
if (r < 0)
return log_error_errno(r, "Failed to attach bus to event loop: %m");
return 0;
}
int manager_start(Manager *m, bool dry_run, int swap_used_limit, int mem_pressure_limit) {
unsigned long l;
int r;
assert(m);
m->dry_run = dry_run;
m->swap_used_limit = swap_used_limit != -1 ? swap_used_limit : DEFAULT_SWAP_USED_LIMIT;
assert(m->swap_used_limit <= 100);
l = mem_pressure_limit != -1 ? mem_pressure_limit : DEFAULT_MEM_PRESSURE_LIMIT;
r = store_loadavg_fixed_point(l, 0, &m->default_mem_pressure_limit);
if (r < 0)
return r;
r = manager_connect_bus(m);
if (r < 0)
return r;
r = acquire_managed_oom_connect(m);
if (r < 0)
return r;
r = monitor_cgroup_contexts(m);
if (r < 0)
return r;
return 0;
}
int manager_get_dump_string(Manager *m, char **ret) {
_cleanup_free_ char *dump = NULL;
_cleanup_fclose_ FILE *f = NULL;
OomdCGroupContext *c;
size_t size;
char *key;
int r;
assert(m);
assert(ret);
f = open_memstream_unlocked(&dump, &size);
if (!f)
return -errno;
fprintf(f,
"Dry Run: %s\n"
"Swap Used Limit: %u%%\n"
"Default Memory Pressure Limit: %lu%%\n"
"System Context:\n",
yes_no(m->dry_run),
m->swap_used_limit,
LOAD_INT(m->default_mem_pressure_limit));
oomd_dump_system_context(&m->system_context, f, "\t");
fprintf(f, "Swap Monitored CGroups:\n");
HASHMAP_FOREACH_KEY(c, key, m->monitored_swap_cgroup_contexts)
oomd_dump_swap_cgroup_context(c, f, "\t");
fprintf(f, "Memory Pressure Monitored CGroups:\n");
HASHMAP_FOREACH_KEY(c, key, m->monitored_mem_pressure_cgroup_contexts)
oomd_dump_memory_pressure_cgroup_context(c, f, "\t");
r = fflush_and_check(f);
if (r < 0)
return r;
f = safe_fclose(f);
*ret = TAKE_PTR(dump);
return 0;
}
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