diff options
Diffstat (limited to 'kernel/cgroup/pids.c')
| -rw-r--r-- | kernel/cgroup/pids.c | 52 |
1 files changed, 46 insertions, 6 deletions
diff --git a/kernel/cgroup/pids.c b/kernel/cgroup/pids.c index 138059eb730d..7695e60bcb40 100644 --- a/kernel/cgroup/pids.c +++ b/kernel/cgroup/pids.c @@ -33,6 +33,7 @@ #include <linux/atomic.h> #include <linux/cgroup.h> #include <linux/slab.h> +#include <linux/sched/task.h> #define PIDS_MAX (PID_MAX_LIMIT + 1ULL) #define PIDS_MAX_STR "max" @@ -46,6 +47,7 @@ struct pids_cgroup { */ atomic64_t counter; atomic64_t limit; + int64_t watermark; /* Handle for "pids.events" */ struct cgroup_file events_file; @@ -84,6 +86,16 @@ static void pids_css_free(struct cgroup_subsys_state *css) kfree(css_pids(css)); } +static void pids_update_watermark(struct pids_cgroup *p, int64_t nr_pids) +{ + /* + * This is racy, but we don't need perfectly accurate tallying of + * the watermark, and this lets us avoid extra atomic overhead. + */ + if (nr_pids > READ_ONCE(p->watermark)) + WRITE_ONCE(p->watermark, nr_pids); +} + /** * pids_cancel - uncharge the local pid count * @pids: the pid cgroup state @@ -127,8 +139,11 @@ static void pids_charge(struct pids_cgroup *pids, int num) { struct pids_cgroup *p; - for (p = pids; parent_pids(p); p = parent_pids(p)) - atomic64_add(num, &p->counter); + for (p = pids; parent_pids(p); p = parent_pids(p)) { + int64_t new = atomic64_add_return(num, &p->counter); + + pids_update_watermark(p, new); + } } /** @@ -155,6 +170,12 @@ static int pids_try_charge(struct pids_cgroup *pids, int num) */ if (new > limit) goto revert; + + /* + * Not technically accurate if we go over limit somewhere up + * the hierarchy, but that's tolerable for the watermark. + */ + pids_update_watermark(p, new); } return 0; @@ -214,13 +235,16 @@ static void pids_cancel_attach(struct cgroup_taskset *tset) * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies * on cgroup_threadgroup_change_begin() held by the copy_process(). */ -static int pids_can_fork(struct task_struct *task) +static int pids_can_fork(struct task_struct *task, struct css_set *cset) { struct cgroup_subsys_state *css; struct pids_cgroup *pids; int err; - css = task_css_check(current, pids_cgrp_id, true); + if (cset) + css = cset->subsys[pids_cgrp_id]; + else + css = task_css_check(current, pids_cgrp_id, true); pids = css_pids(css); err = pids_try_charge(pids, 1); if (err) { @@ -235,12 +259,15 @@ static int pids_can_fork(struct task_struct *task) return err; } -static void pids_cancel_fork(struct task_struct *task) +static void pids_cancel_fork(struct task_struct *task, struct css_set *cset) { struct cgroup_subsys_state *css; struct pids_cgroup *pids; - css = task_css_check(current, pids_cgrp_id, true); + if (cset) + css = cset->subsys[pids_cgrp_id]; + else + css = task_css_check(current, pids_cgrp_id, true); pids = css_pids(css); pids_uncharge(pids, 1); } @@ -304,6 +331,14 @@ static s64 pids_current_read(struct cgroup_subsys_state *css, return atomic64_read(&pids->counter); } +static s64 pids_peak_read(struct cgroup_subsys_state *css, + struct cftype *cft) +{ + struct pids_cgroup *pids = css_pids(css); + + return READ_ONCE(pids->watermark); +} + static int pids_events_show(struct seq_file *sf, void *v) { struct pids_cgroup *pids = css_pids(seq_css(sf)); @@ -325,6 +360,11 @@ static struct cftype pids_files[] = { .flags = CFTYPE_NOT_ON_ROOT, }, { + .name = "peak", + .flags = CFTYPE_NOT_ON_ROOT, + .read_s64 = pids_peak_read, + }, + { .name = "events", .seq_show = pids_events_show, .file_offset = offsetof(struct pids_cgroup, events_file), |