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 v1 behavior remains non-hierarchical.
Signed-off-by: Michal Koutný <[email protected]> --- Documentation/admin-guide/cgroup-v2.rst | 4 ++- kernel/cgroup/pids.c | 46 ++++++++++++++++--------- 2 files changed, 33 insertions(+), 17 deletions(-) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 4f04538d688c..5d4c505cae06 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -2189,7 +2189,9 @@ PID Interface Files pids.events A read-only flat-keyed file which exists on non-root cgroups. Unless specified otherwise, a value change in this file generates a file modified - event. The following entries are defined. + event. Fields in this file are hierarchical and the file modified event + can be generated due to an event down the hierarchy. The following + entries are defined. max The number of times the limit of the cgroup was hit. diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index 471562609eef..76c0a97e42da 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; + + /* Only log the first time limit is hit. */ + if (atomic64_inc_return(&p->events[PIDCG_MAX_IMPOSED]) == 1) { + pr_info("cgroup: fork rejected by pids controller in "); + pr_cont_cgroup_path(p->css.cgroup); + pr_cont("\n"); + } + /* Events are only notified in pids_forking on v1 */ + if (!cgroup_subsys_on_dfl(pids_cgrp_subsys)) + return; + + for (; parent_pids(p); p = parent_pids(p)) { + atomic64_inc(&p->events[PIDCG_MAX_IMPOSED]); + + 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_MAX_IMPOSED]) == 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; } -- 2.44.0
