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cgroup: when we fail to clean up a cgroup, let's ask PID 1 for help

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This commit is contained in:
Lennart Poettering 2024-11-12 12:03:05 +01:00
parent dd0b3a9215
commit 5f1ac9e3c0
1 changed files with 58 additions and 7 deletions
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65
src/core/cgroup.c
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@ -3610,6 +3610,49 @@ static bool unit_maybe_release_cgroup(Unit *u) {
return false;
}
static int unit_prune_cgroup_via_bus(Unit *u) {
_cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
int r;
assert(u);
if (MANAGER_IS_SYSTEM(u->manager))
return -EINVAL;
if (!u->manager->system_bus)
return -EIO;
CGroupRuntime *crt = unit_get_cgroup_runtime(u);
if (!crt || !crt->cgroup_path)
return -EOWNERDEAD;
/* Determine this unit's cgroup path relative to our cgroup root */
const char *pp = path_startswith(crt->cgroup_path, u->manager->cgroup_root);
if (!pp)
return -EINVAL;
_cleanup_free_ char *absolute = NULL;
if (!path_is_absolute(pp)) { /* RemoveSubgroupFromUnit() wants an absolute path */
absolute = strjoin("/", pp);
if (!absolute)
return -ENOMEM;
pp = absolute;
}
r = bus_call_method(u->manager->system_bus,
bus_systemd_mgr,
"RemoveSubgroupFromUnit",
&error, NULL,
"ss",
NULL /* empty unit name means client's unit, i.e. us */,
pp);
if (r < 0)
return log_unit_debug_errno(u, r, "Failed to trim cgroup via the bus: %s", bus_error_message(&error, r));
return 0;
}
void unit_prune_cgroup(Unit *u) {
bool is_root_slice;
int r;
@ -3641,13 +3684,21 @@ void unit_prune_cgroup(Unit *u) {
is_root_slice = unit_has_name(u, SPECIAL_ROOT_SLICE);
r = cg_trim_everywhere(u->manager->cgroup_supported, crt->cgroup_path, !is_root_slice);
if (r < 0)
/* One reason we could have failed here is, that the cgroup still contains a process.
* However, if the cgroup becomes removable at a later time, it might be removed when
* the containing slice is stopped. So even if we failed now, this unit shouldn't assume
* that the cgroup is still realized the next time it is started. Do not return early
* on error, continue cleanup. */
log_unit_full_errno(u, r == -EBUSY ? LOG_DEBUG : LOG_WARNING, r, "Failed to destroy cgroup %s, ignoring: %m", empty_to_root(crt->cgroup_path));
if (r < 0) {
int k = unit_prune_cgroup_via_bus(u);
if (k >= 0)
log_unit_debug_errno(u, r, "Failed to destroy cgroup %s on our own (%m), but worked when talking to PID 1.", empty_to_root(crt->cgroup_path));
else {
/* One reason we could have failed here is, that the cgroup still contains a process.
* However, if the cgroup becomes removable at a later time, it might be removed when
* the containing slice is stopped. So even if we failed now, this unit shouldn't
* assume that the cgroup is still realized the next time it is started. Do not
* return early on error, continue cleanup. */
log_unit_full_errno(u, r == -EBUSY ? LOG_DEBUG : LOG_WARNING, r,
"Failed to destroy cgroup %s, ignoring: %m", empty_to_root(crt->cgroup_path));
}
}
if (is_root_slice)
return;