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Merge pull request #23764 from enr0n/oomd-allow-managed-oom-preference

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oomd: allow ManagedOOMPreference on all cgroups
This commit is contained in:
Yu Watanabe
2022-08-27 14:05:10 +09:00
committed by GitHub
parent 91685cf9f1 b814de3054
commit a3dd119b35
5 changed files with 163 additions and 71 deletions
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man/systemd.resource-control.xml
+14 -3
View File
@@ -1077,9 +1077,20 @@ DeviceAllow=/dev/loop-control
<para>Allows deprioritizing or omitting this unit's cgroup as a candidate when
<command>systemd-oomd</command> needs to act. Requires support for extended attributes (see
<citerefentry project='man-pages'><refentrytitle>xattr</refentrytitle><manvolnum>7</manvolnum></citerefentry>)
in order to use <option>avoid</option> or <option>omit</option>. Additionally,
<command>systemd-oomd</command> will ignore these extended attributes if the unit's cgroup is not
owned by the root user.</para>
in order to use <option>avoid</option> or <option>omit</option>.</para>
<para>When calculating candidates to relieve swap usage, <command>systemd-oomd</command> will
only respect these extended attributes if the unit's cgroup is owned by root.</para>
<para>When calculating candidates to relieve memory pressure, <command>systemd-oomd</command>
will only respect these extended attributes if the unit's cgroup owner, and the
owner of the monitored ancestor cgroup are the same. For example, if <command>systemd-oomd</command>
is calculating candidates for <filename>-.slice</filename>, then extended attributes set
on descendants of <filename>/user.slice/user-1000.slice/user@1000.service/</filename>
will be ignored because the descendants are owned by UID 1000, and <filename>-.slice</filename>
is owned by UID 0. But, if calculating candidates for
<filename>/user.slice/user-1000.slice/user@1000.service/</filename>, then extended attributes set
on the descendants would be respected.</para>
<para>If this property is set to <option>avoid</option>, the service manager will convey this to
<command>systemd-oomd</command>, which will only select this cgroup if there are no other viable
src/core/cgroup.c
+3 -2
View File
@@ -783,6 +783,9 @@ static void cgroup_xattr_apply(Unit *u) {
assert(u);
/* The 'user.*' xattrs can be set from a user manager. */
cgroup_oomd_xattr_apply(u, u->cgroup_path);
if (!MANAGER_IS_SYSTEM(u->manager))
return;
@@ -809,8 +812,6 @@ static void cgroup_xattr_apply(Unit *u) {
else
unit_remove_xattr_graceful(u, NULL, xn);
}
cgroup_oomd_xattr_apply(u, u->cgroup_path);
}
static int lookup_block_device(const char *p, dev_t *ret) {
src/oom/oomd-util.c
+54 -21
View File
@@ -14,6 +14,7 @@
#include "sort-util.h"
#include "stat-util.h"
#include "stdio-util.h"
#include "user-util.h"
DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(
oomd_cgroup_ctx_hash_ops,
@@ -142,10 +143,53 @@ bool oomd_swap_free_below(const OomdSystemContext *ctx, int threshold_permyriad)
return (ctx->swap_total - ctx->swap_used) < swap_threshold;
}
int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix) {
uid_t uid, prefix_uid;
int r;
assert(ctx);
prefix = empty_to_root(prefix);
if (!path_startswith(ctx->path, prefix))
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
"%s is not a descendant of %s", ctx->path, prefix);
r = cg_get_owner(SYSTEMD_CGROUP_CONTROLLER, ctx->path, &uid);
if (r < 0)
return log_debug_errno(r, "Failed to get owner/group from %s: %m", ctx->path);
r = cg_get_owner(SYSTEMD_CGROUP_CONTROLLER, prefix, &prefix_uid);
if (r < 0)
return log_debug_errno(r, "Failed to get owner/group from %s: %m", ctx->path);
if (uid == prefix_uid) {
/* Ignore most errors when reading the xattr since it is usually unset and cgroup xattrs are only used
* as an optional feature of systemd-oomd (and the system might not even support them). */
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_avoid");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && r != -ENODATA)
log_debug_errno(r, "Failed to get xattr user.oomd_avoid, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_AVOID : ctx->preference;
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_omit");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && r != -ENODATA)
log_debug_errno(r, "Failed to get xattr user.oomd_omit, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_OMIT : ctx->preference;
} else
ctx->preference = MANAGED_OOM_PREFERENCE_NONE;
return 0;
}
int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const char *prefix, OomdCGroupContext ***ret) {
_cleanup_free_ OomdCGroupContext **sorted = NULL;
OomdCGroupContext *item;
size_t k = 0;
int r;
assert(h);
assert(compare_func);
@@ -157,7 +201,14 @@ int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const cha
HASHMAP_FOREACH(item, h) {
/* Skip over cgroups that are not valid candidates or are explicitly marked for omission */
if ((item->path && prefix && !path_startswith(item->path, prefix)) || item->preference == MANAGED_OOM_PREFERENCE_OMIT)
if (item->path && prefix && !path_startswith(item->path, prefix))
continue;
r = oomd_fetch_cgroup_oom_preference(item, prefix);
if (r == -ENOMEM)
return r;
if (item->preference == MANAGED_OOM_PREFERENCE_OMIT)
continue;
sorted[k++] = item;
@@ -272,7 +323,7 @@ int oomd_kill_by_pgscan_rate(Hashmap *h, const char *prefix, bool dry_run, char
continue; /* Try to find something else to kill */
}
dump_until = MAX(dump_until, i);
dump_until = MAX(dump_until, i + 1);
char *selected = strdup(sorted[i]->path);
if (!selected)
return -ENOMEM;
@@ -316,7 +367,7 @@ int oomd_kill_by_swap_usage(Hashmap *h, uint64_t threshold_usage, bool dry_run,
continue; /* Try to find something else to kill */
}
dump_until = MAX(dump_until, i);
dump_until = MAX(dump_until, i + 1);
char *selected = strdup(sorted[i]->path);
if (!selected)
return -ENOMEM;
@@ -334,7 +385,6 @@ int oomd_cgroup_context_acquire(const char *path, OomdCGroupContext **ret) {
_cleanup_(oomd_cgroup_context_freep) OomdCGroupContext *ctx = NULL;
_cleanup_free_ char *p = NULL, *val = NULL;
bool is_root;
uid_t uid;
int r;
assert(path);
@@ -355,23 +405,6 @@ int oomd_cgroup_context_acquire(const char *path, OomdCGroupContext **ret) {
if (r < 0)
return log_debug_errno(r, "Error parsing memory pressure from %s: %m", p);
r = cg_get_owner(SYSTEMD_CGROUP_CONTROLLER, path, &uid);
if (r < 0)
log_debug_errno(r, "Failed to get owner/group from %s: %m", path);
else if (uid == 0) {
/* Ignore most errors when reading the xattr since it is usually unset and cgroup xattrs are only used
* as an optional feature of systemd-oomd (and the system might not even support them). */
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, path, "user.oomd_avoid");
if (r == -ENOMEM)
return r;
ctx->preference = r == 1 ? MANAGED_OOM_PREFERENCE_AVOID : ctx->preference;
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, path, "user.oomd_omit");
if (r == -ENOMEM)
return r;
ctx->preference = r == 1 ? MANAGED_OOM_PREFERENCE_OMIT : ctx->preference;
}
if (is_root) {
r = procfs_memory_get_used(&ctx->current_memory_usage);
if (r < 0)
src/oom/oomd-util.h
+9
View File
@@ -109,6 +109,15 @@ static inline int compare_swap_usage(OomdCGroupContext * const *c1, OomdCGroupCo
* Returns the number of sorted items; negative on error. */
int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const char *prefix, OomdCGroupContext ***ret);
/* If the cgroups represented by `ctx` and `prefix` are owned by the same user,
* then set `ctx->preference` using the `user.oomd_avoid` and `user.oomd_omit`
* xattrs. Otherwise, set `ctx->preference` to MANAGED_OOM_PREFERENCE_NONE.
*
* If `prefix` is NULL or the empty string, it is treated as root. If `prefix`
* does not specify an ancestor cgroup of `ctx`, -EINVAL is returned. Returns
* negative on all other errors. */
int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix);
/* Returns a negative value on error, 0 if no processes were killed, or 1 if processes were killed. */
int oomd_cgroup_kill(const char *path, bool recurse, bool dry_run);
src/oom/test-oomd-util.c
+83 -45
View File
@@ -94,11 +94,8 @@ static void test_oomd_cgroup_context_acquire_and_insert(void) {
_cleanup_hashmap_free_ Hashmap *h1 = NULL, *h2 = NULL;
_cleanup_(oomd_cgroup_context_freep) OomdCGroupContext *ctx = NULL;
_cleanup_free_ char *cgroup = NULL;
ManagedOOMPreference root_pref;
OomdCGroupContext *c1, *c2;
CGroupMask mask;
bool test_xattrs;
int root_xattrs, r;
if (geteuid() != 0)
return (void) log_tests_skipped("not root");
@@ -115,17 +112,6 @@ static void test_oomd_cgroup_context_acquire_and_insert(void) {
return (void) log_tests_skipped("cgroup memory controller is not available");
assert_se(cg_pid_get_path(NULL, 0, &cgroup) >= 0);
/* If we don't have permissions to set xattrs we're likely in a userns or missing capabilities
* so skip the xattr portions of the test. */
r = cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_test", "1", 1, 0);
test_xattrs = !ERRNO_IS_PRIVILEGE(r) && !ERRNO_IS_NOT_SUPPORTED(r);
if (test_xattrs) {
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_omit", "1", 1, 0) >= 0);
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_avoid", "1", 1, 0) >= 0);
}
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
assert_se(streq(ctx->path, cgroup));
@@ -135,34 +121,11 @@ static void test_oomd_cgroup_context_acquire_and_insert(void) {
assert_se(ctx->swap_usage == 0);
assert_se(ctx->last_pgscan == 0);
assert_se(ctx->pgscan == 0);
/* omit takes precedence over avoid when both are set to true */
if (test_xattrs)
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_OMIT);
else
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_NONE);
ctx = oomd_cgroup_context_free(ctx);
/* also check when only avoid is set to true */
if (test_xattrs) {
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_omit", "0", 1, 0) >= 0);
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_avoid", "1", 1, 0) >= 0);
}
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
if (test_xattrs)
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_AVOID);
ctx = oomd_cgroup_context_free(ctx);
/* Test the root cgroup */
/* Root cgroup is live and not made on demand like the cgroup the test runs in. It can have varying
* xattrs set already so let's read in the booleans first to get the final preference value. */
root_xattrs = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, "", "user.oomd_omit");
root_pref = root_xattrs > 0 ? MANAGED_OOM_PREFERENCE_OMIT : MANAGED_OOM_PREFERENCE_NONE;
root_xattrs = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, "", "user.oomd_avoid");
root_pref = root_xattrs > 0 ? MANAGED_OOM_PREFERENCE_AVOID : MANAGED_OOM_PREFERENCE_NONE;
assert_se(oomd_cgroup_context_acquire("", &ctx) == 0);
assert_se(streq(ctx->path, "/"));
assert_se(ctx->current_memory_usage > 0);
assert_se(ctx->preference == root_pref);
/* Test hashmap inserts */
assert_se(h1 = hashmap_new(&oomd_cgroup_ctx_hash_ops));
@@ -187,14 +150,6 @@ static void test_oomd_cgroup_context_acquire_and_insert(void) {
assert_se(c2->mem_pressure_limit == 6789);
assert_se(c2->mem_pressure_limit_hit_start == 42);
assert_se(c2->last_had_mem_reclaim == 888); /* assumes the live pgscan is less than UINT64_MAX */
/* Assert that avoid/omit are not set if the cgroup is not owned by root */
if (test_xattrs) {
ctx = oomd_cgroup_context_free(ctx);
assert_se(cg_set_access(SYSTEMD_CGROUP_CONTROLLER, cgroup, 65534, 0) >= 0);
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_NONE);
}
}
static void test_oomd_update_cgroup_contexts_between_hashmaps(void) {
@@ -451,6 +406,88 @@ static void test_oomd_sort_cgroups(void) {
sorted_cgroups = mfree(sorted_cgroups);
}
static void test_oomd_fetch_cgroup_oom_preference(void) {
_cleanup_(oomd_cgroup_context_freep) OomdCGroupContext *ctx = NULL;
_cleanup_free_ char *cgroup = NULL;
ManagedOOMPreference root_pref;
CGroupMask mask;
bool test_xattrs;
int root_xattrs, r;
if (geteuid() != 0)
return (void) log_tests_skipped("not root");
if (!is_pressure_supported())
return (void) log_tests_skipped("system does not support pressure");
if (cg_all_unified() <= 0)
return (void) log_tests_skipped("cgroups are not running in unified mode");
assert_se(cg_mask_supported(&mask) >= 0);
if (!FLAGS_SET(mask, CGROUP_MASK_MEMORY))
return (void) log_tests_skipped("cgroup memory controller is not available");
assert_se(cg_pid_get_path(NULL, 0, &cgroup) >= 0);
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
/* If we don't have permissions to set xattrs we're likely in a userns or missing capabilities
* so skip the xattr portions of the test. */
r = cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_test", "1", 1, 0);
test_xattrs = !ERRNO_IS_PRIVILEGE(r) && !ERRNO_IS_NOT_SUPPORTED(r);
if (test_xattrs) {
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) == 0);
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_omit", "1", 1, 0) >= 0);
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_avoid", "1", 1, 0) >= 0);
/* omit takes precedence over avoid when both are set to true */
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) == 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_OMIT);
} else {
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) < 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_NONE);
}
ctx = oomd_cgroup_context_free(ctx);
/* also check when only avoid is set to true */
if (test_xattrs) {
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_omit", "0", 1, 0) >= 0);
assert_se(cg_set_xattr(SYSTEMD_CGROUP_CONTROLLER, cgroup, "user.oomd_avoid", "1", 1, 0) >= 0);
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) == 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_AVOID);
ctx = oomd_cgroup_context_free(ctx);
}
/* Test the root cgroup */
/* Root cgroup is live and not made on demand like the cgroup the test runs in. It can have varying
* xattrs set already so let's read in the booleans first to get the final preference value. */
assert_se(oomd_cgroup_context_acquire("", &ctx) == 0);
root_xattrs = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, "", "user.oomd_omit");
root_pref = root_xattrs > 0 ? MANAGED_OOM_PREFERENCE_OMIT : MANAGED_OOM_PREFERENCE_NONE;
root_xattrs = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, "", "user.oomd_avoid");
root_pref = root_xattrs > 0 ? MANAGED_OOM_PREFERENCE_AVOID : MANAGED_OOM_PREFERENCE_NONE;
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) == 0);
assert_se(ctx->preference == root_pref);
assert_se(oomd_fetch_cgroup_oom_preference(ctx, "/herp.slice/derp.scope") == -EINVAL);
/* Assert that avoid/omit are not set if the cgroup and prefix are not
* owned by the same user.*/
if (test_xattrs && !empty_or_root(ctx->path)) {
ctx = oomd_cgroup_context_free(ctx);
assert_se(cg_set_access(SYSTEMD_CGROUP_CONTROLLER, cgroup, 65534, 0) >= 0);
assert_se(oomd_cgroup_context_acquire(cgroup, &ctx) == 0);
assert_se(oomd_fetch_cgroup_oom_preference(ctx, NULL) == 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_NONE);
assert_se(oomd_fetch_cgroup_oom_preference(ctx, ctx->path) == 0);
assert_se(ctx->preference == MANAGED_OOM_PREFERENCE_AVOID);
}
}
int main(void) {
int r;
@@ -470,6 +507,7 @@ int main(void) {
test_oomd_cgroup_kill();
test_oomd_cgroup_context_acquire_and_insert();
test_oomd_fetch_cgroup_oom_preference();
return 0;
}