[PATCH] psi oom

[Johannes Weiner]

---
 include/linux/psi_types.h |  4 +++
 kernel/sched/psi.c        | 52 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h
index 07aaf9b82241..390446b07ac7 100644
--- a/include/linux/psi_types.h
+++ b/include/linux/psi_types.h
@@ -162,6 +162,10 @@ struct psi_group {
 	u64 polling_total[NR_PSI_STATES - 1];
 	u64 polling_next_update;
 	u64 polling_until;
+
+	/* Out-of-memory situation tracking */
+	bool oom_pressure;
+	u64 oom_pressure_start;
 };
 
 #else /* CONFIG_PSI */
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index f28342dc65ec..1027b6611ec2 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -139,6 +139,7 @@
 #include <linux/ctype.h>
 #include <linux/file.h>
 #include <linux/poll.h>
+#include <linux/oom.h>
 #include <linux/psi.h>
 #include "sched.h"
 
@@ -177,6 +178,8 @@ struct psi_group psi_system = {
 	.pcpu = &system_group_pcpu,
 };
 
+static void psi_oom_tick(struct psi_group *group, u64 now);
+
 static void psi_avgs_work(struct work_struct *work);
 
 static void group_init(struct psi_group *group)
@@ -403,6 +406,8 @@ static u64 update_averages(struct psi_group *group, u64 now)
 		calc_avgs(group->avg[s], missed_periods, sample, period);
 	}
 
+	psi_oom_tick(group, now);
+
 	return avg_next_update;
 }
 
@@ -1280,3 +1285,50 @@ static int __init psi_proc_init(void)
 	return 0;
 }
 module_init(psi_proc_init);
+
+#define OOM_PRESSURE_LEVEL	80
+#define OOM_PRESSURE_PERIOD	(10 * NSEC_PER_SEC)
+
+static void psi_oom_tick(struct psi_group *group, u64 now)
+{
+	struct oom_control oc = {
+		.order = 0,
+	};
+	unsigned long pressure;
+	bool high;
+
+	/*
+	 * Protect the system from livelocking due to thrashing. Leave
+	 * per-cgroup policies to oomd, lmkd etc.
+	 */
+	if (group != &psi_system)
+		return;
+
+	pressure = LOAD_INT(group->avg[PSI_MEM_FULL][0]);
+	high = pressure >= OOM_PRESSURE_LEVEL;
+
+	if (!group->oom_pressure && !high)
+		return;
+
+	if (!group->oom_pressure && high) {
+		group->oom_pressure = true;
+		group->oom_pressure_start = now;
+		return;
+	}
+
+	if (group->oom_pressure && !high) {
+		group->oom_pressure = false;
+		return;
+	}
+
+	if (now < group->oom_pressure_start + OOM_PRESSURE_PERIOD)
+		return;
+
+	group->oom_pressure = false;
+
+	if (!mutex_trylock(&oom_lock))
+		return;
+	pr_warn("Excessive and sustained system-wide memory pressure!\n");
+	out_of_memory(&oc);
+	mutex_unlock(&oom_lock);
+}
-- 
2.22.0