The pids.events file should honor the hierarchy, so make the events propagate from their origin up to the root on the unified hierarchy. The legacy behavior remains non-hierarchical.
Signed-off-by: Michal Koutný mkoutny@suse.com --- Documentation/admin-guide/cgroup-v2.rst | 9 +++-- kernel/cgroup/pids.c | 46 ++++++++++++++++--------- 2 files changed, 36 insertions(+), 19 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 945ff743a3c9..0b5f77104e8b 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -240,8 +240,11 @@ cgroup v2 currently supports the following mount options. v2 is remounted later on).
pids_localevents - Represent fork failures inside cgroup's pids.events:max (v1 behavior), - not its limit being hit (v2 behavior). + The option restores v1-like behavior of pids.events:max, that is only + local (inside cgroup proper) fork failures are counted. Without this + option pids.events.max represents any pids.max enforcemnt across + cgroup's subtree. +
Organizing Processes and Threads @@ -2205,7 +2208,7 @@ PID Interface Files modified event. The following entries are defined.
max - The number of times the cgroup's number of processes hit the + The number of times the cgroup's total number of processes hit the pids.max limit (see also pids_localevents).
Organisational operations are not blocked by cgroup policies, so it is diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index a557f5c8300b..c09b744d548c 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -238,6 +238,34 @@ static void pids_cancel_attach(struct cgroup_taskset *tset) } }
+static void pids_event(struct pids_cgroup *pids_forking, + struct pids_cgroup *pids_over_limit) +{ + struct pids_cgroup *p = pids_forking; + bool limit = false; + + for (; parent_pids(p); p = parent_pids(p)) { + /* Only log the first time limit is hit. */ + if (atomic64_inc_return(&p->events[PIDCG_FORKFAIL]) == 1) { + pr_info("cgroup: fork rejected by pids controller in "); + pr_cont_cgroup_path(p->css.cgroup); + pr_cont("\n"); + } + cgroup_file_notify(&p->events_file); + + if (!cgroup_subsys_on_dfl(pids_cgrp_subsys) || + cgrp_dfl_root.flags & CGRP_ROOT_PIDS_LOCAL_EVENTS) + break; + + if (p == pids_over_limit) + limit = true; + if (limit) + atomic64_inc(&p->events[PIDCG_MAX]); + + cgroup_file_notify(&p->events_file); + } +} + /* * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies * on cgroup_threadgroup_change_begin() held by the copy_process(). @@ -254,23 +282,9 @@ static int pids_can_fork(struct task_struct *task, struct css_set *cset) css = task_css_check(current, pids_cgrp_id, true); pids = css_pids(css); err = pids_try_charge(pids, 1, &pids_over_limit); - if (err) { - /* compatibility on v1 where events were notified in leaves. */ - if (!cgroup_subsys_on_dfl(pids_cgrp_subsys)) - pids_over_limit = pids; - - /* Only log the first time limit is hit. */ - if (atomic64_inc_return(&pids->events[PIDCG_FORKFAIL]) == 1) { - pr_info("cgroup: fork rejected by pids controller in "); - pr_cont_cgroup_path(pids->css.cgroup); - pr_cont("\n"); - } - atomic64_inc(&pids_over_limit->events[PIDCG_MAX]); + if (err) + pids_event(pids, pids_over_limit);
- cgroup_file_notify(&pids->events_file); - if (pids_over_limit != pids) - cgroup_file_notify(&pids_over_limit->events_file); - } return err; }