Hierarchical counting of events is not practical for watching when a particular pids.max is being hit. Therefore introduce .local flavor of events file (akin to memory controller) that collects only events relevant to given cgroup.
Signed-off-by: Michal Koutný <[email protected]> --- kernel/cgroup/pids.c | 41 +++++++++++++++++++++++++++++++++-------- 1 file changed, 33 insertions(+), 8 deletions(-) diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index 76c0a97e42da..f5f81274658e 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -57,10 +57,12 @@ struct pids_cgroup { atomic64_t limit; int64_t watermark; - /* Handle for "pids.events" */ + /* Handles for pids.events[.local] */ struct cgroup_file events_file; + struct cgroup_file events_local_file; atomic64_t events[NR_PIDCG_EVENTS]; + atomic64_t events_local[NR_PIDCG_EVENTS]; }; static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css) @@ -245,11 +247,12 @@ static void pids_event(struct pids_cgroup *pids_forking, bool limit = false; /* Only log the first time limit is hit. */ - if (atomic64_inc_return(&p->events[PIDCG_MAX_IMPOSED]) == 1) { + if (atomic64_inc_return(&p->events_local[PIDCG_MAX_IMPOSED]) == 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_local_file); /* Events are only notified in pids_forking on v1 */ if (!cgroup_subsys_on_dfl(pids_cgrp_subsys)) return; @@ -257,8 +260,11 @@ static void pids_event(struct pids_cgroup *pids_forking, for (; parent_pids(p); p = parent_pids(p)) { atomic64_inc(&p->events[PIDCG_MAX_IMPOSED]); - if (p == pids_over_limit) + if (p == pids_over_limit) { limit = true; + atomic64_inc(&p->events_local[PIDCG_MAX]); + cgroup_file_notify(&p->events_local_file); + } if (limit) atomic64_inc(&p->events[PIDCG_MAX]); @@ -368,12 +374,25 @@ static s64 pids_peak_read(struct cgroup_subsys_state *css, return READ_ONCE(pids->watermark); } -static int pids_events_show(struct seq_file *sf, void *v) +static int __pids_events_show(struct seq_file *sf, bool local) { struct pids_cgroup *pids = css_pids(seq_css(sf)); + atomic64_t *events = local ? pids->events_local : pids->events; + + seq_printf(sf, "max %lld\n", (s64)atomic64_read(&events[PIDCG_MAX])); + seq_printf(sf, "max.imposed %lld\n", (s64)atomic64_read(&events[PIDCG_MAX_IMPOSED])); + return 0; +} + +static int pids_events_show(struct seq_file *sf, void *v) +{ + __pids_events_show(sf, false); + return 0; +} - seq_printf(sf, "max %lld\n", (s64)atomic64_read(&pids->events[PIDCG_MAX])); - seq_printf(sf, "max.imposed %lld\n", (s64)atomic64_read(&pids->events[PIDCG_MAX_IMPOSED])); +static int pids_events_local_show(struct seq_file *sf, void *v) +{ + __pids_events_show(sf, true); return 0; } @@ -381,7 +400,7 @@ static int pids_events_show_legacy(struct seq_file *sf, void *v) { struct pids_cgroup *pids = css_pids(seq_css(sf)); - seq_printf(sf, "max%lld\n", (s64)atomic64_read(&pids->events[PIDCG_MAX_IMPOSED])); + seq_printf(sf, "max%lld\n", (s64)atomic64_read(&pids->events_local[PIDCG_MAX_IMPOSED])); return 0; } @@ -408,6 +427,12 @@ static struct cftype pids_files[] = { .file_offset = offsetof(struct pids_cgroup, events_file), .flags = CFTYPE_NOT_ON_ROOT, }, + { + .name = "events.local", + .seq_show = pids_events_local_show, + .file_offset = offsetof(struct pids_cgroup, events_file), + .flags = CFTYPE_NOT_ON_ROOT, + }, { } /* terminate */ }; @@ -426,7 +451,7 @@ static struct cftype pids_files_legacy[] = { { .name = "events", .seq_show = pids_events_show_legacy, - .file_offset = offsetof(struct pids_cgroup, events_file), + .file_offset = offsetof(struct pids_cgroup, events_local_file), .flags = CFTYPE_NOT_ON_ROOT, }, { } /* terminate */ -- 2.44.0
