[RFC PATCH 08/11] soc: mediatek: dram-ecc: add the corrected error leaky bucket
santino.wang
santino.wang at mediatek.com
Mon Nov 2 01:23:30 PST 2026
From: Santino Wang <santino.wang at mediatek.com>
A page with repeated corrected errors is likely to fail. Count the
corrected errors per page in a leaky bucket and retire the page with
memory_failure() when the count reaches a threshold. The bucket decays
over time, and its threshold, decay interval and the number of tracked
pages are configurable through sysfs.
Signed-off-by: Santino Wang <santino.wang at mediatek.com>
---
drivers/soc/mediatek/dram-ecc/core/Makefile | 1 +
.../mediatek/dram-ecc/core/ghes_notifier.c | 2 +
.../dram-ecc/core/policy/leaky_bucket.c | 277 ++++++++++++++++++
.../mediatek/dram-ecc/core/policy/policy.c | 9 +-
.../mediatek/dram-ecc/core/policy/policy.h | 4 +
5 files changed, 292 insertions(+), 1 deletion(-)
create mode 100644 drivers/soc/mediatek/dram-ecc/core/policy/leaky_bucket.c
diff --git a/drivers/soc/mediatek/dram-ecc/core/Makefile b/drivers/soc/mediatek/dram-ecc/core/Makefile
index d8d878f321d4..7c973831c9ef 100644
--- a/drivers/soc/mediatek/dram-ecc/core/Makefile
+++ b/drivers/soc/mediatek/dram-ecc/core/Makefile
@@ -12,6 +12,7 @@ mtk_dram_ecc-y := \
policy/policy.o \
policy/containment.o \
policy/storm_protection.o \
+ policy/leaky_bucket.o \
policy/address_range.o
CFLAGS_trace.o := -I$(src)
diff --git a/drivers/soc/mediatek/dram-ecc/core/ghes_notifier.c b/drivers/soc/mediatek/dram-ecc/core/ghes_notifier.c
index 633bf89e2231..a010ca652e86 100644
--- a/drivers/soc/mediatek/dram-ecc/core/ghes_notifier.c
+++ b/drivers/soc/mediatek/dram-ecc/core/ghes_notifier.c
@@ -28,6 +28,7 @@
#include "mtk_dram_ecc_event.h"
#include "ghes_notifier.h"
#include "counters.h"
+#include "policy/policy.h"
#include "trace.h"
static ATOMIC_NOTIFIER_HEAD(mtk_dram_ecc_notifier_chain);
@@ -249,6 +250,7 @@ static int mtk_ghes_vendor_cb(struct notifier_block *nb, unsigned long severity,
spin_unlock(&addr_lock);
trace_mtk_dram_ecc_ce(evt.spa, evt.channel, evt.subchannel, evt.rank,
evt.bank, evt.row, evt.column);
+ leaky_bucket_hit(evt.spa);
ret = atomic_notifier_call_chain(&mtk_dram_ecc_notifier_chain,
MTK_DRAM_ECC_NOTIFY_CE, &evt);
if (ret == NOTIFY_BAD)
diff --git a/drivers/soc/mediatek/dram-ecc/core/policy/leaky_bucket.c b/drivers/soc/mediatek/dram-ecc/core/policy/leaky_bucket.c
new file mode 100644
index 000000000000..a51793d53efb
--- /dev/null
+++ b/drivers/soc/mediatek/dram-ecc/core/policy/leaky_bucket.c
@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026 MediaTek Inc.
+ */
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/string.h>
+#include <linux/hashtable.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+#include <linux/mm.h>
+#include <linux/jiffies.h>
+#include <linux/errno.h>
+#include <linux/printk.h>
+
+#include "../counters.h"
+#include "../mtk_dram_ecc.h"
+#include "../trace.h"
+#include "policy.h"
+
+/* ------------------------------------------------------------------ */
+/* Per-page counter table */
+/* ------------------------------------------------------------------ */
+
+struct lb_entry {
+ struct hlist_node node;
+ u64 pfn;
+ u32 count;
+};
+
+#define LB_HASH_BITS 8 /* 256 buckets */
+
+static DECLARE_HASHTABLE(lb_table, LB_HASH_BITS);
+static DEFINE_SPINLOCK(lb_lock);
+static unsigned int lb_tracked; /* number of entries currently in table */
+
+/* ------------------------------------------------------------------ */
+/* Decay timer (delayed_work) */
+/* ------------------------------------------------------------------ */
+
+static struct delayed_work lb_decay_work;
+
+static void lb_decay_fn(struct work_struct *work)
+{
+ struct lb_entry *e;
+ struct hlist_node *tmp;
+ unsigned int bkt;
+ bool reschedule = false;
+
+ spin_lock(&lb_lock);
+ hash_for_each_safe(lb_table, bkt, tmp, e, node) {
+ if (e->count > 0)
+ e->count--;
+ if (e->count == 0) {
+ hash_del(&e->node);
+ kfree(e);
+ lb_tracked--;
+ } else {
+ reschedule = true;
+ }
+ }
+ spin_unlock(&lb_lock);
+
+ if (reschedule)
+ schedule_delayed_work(&lb_decay_work,
+ secs_to_jiffies(mtk_ecc_data.lb_decay_interval_sec));
+}
+
+/* ------------------------------------------------------------------ */
+/* leaky_bucket_hit - called from ghes_notifier.c on every CE event */
+/* ------------------------------------------------------------------ */
+
+void leaky_bucket_hit(u64 spa)
+{
+ u64 pfn = spa >> PAGE_SHIFT;
+ struct lb_entry *e;
+ bool found = false;
+ bool start_timer = false;
+ bool retired = false;
+ u32 count = 0;
+ int ret;
+
+ spin_lock(&lb_lock);
+
+ hash_for_each_possible(lb_table, e, node, pfn) {
+ if (e->pfn == pfn) {
+ e->count++;
+ count = e->count;
+ found = true;
+ break;
+ }
+ }
+
+ if (!found) {
+ if (lb_tracked < mtk_ecc_data.lb_max_tracked) {
+ e = kzalloc_obj(*e, GFP_ATOMIC);
+ if (e) {
+ e->pfn = pfn;
+ e->count = 1;
+ count = 1;
+ hash_add(lb_table, &e->node, pfn);
+ lb_tracked++;
+ /* start timer only when table was empty */
+ if (lb_tracked == 1)
+ start_timer = true;
+ }
+ }
+ }
+
+ spin_unlock(&lb_lock);
+
+ if (start_timer)
+ schedule_delayed_work(&lb_decay_work,
+ secs_to_jiffies(mtk_ecc_data.lb_decay_interval_sec));
+
+ if (count >= mtk_ecc_data.lb_threshold && mtk_ecc_data.lb_threshold > 0) {
+ ret = memory_failure(pfn, 0);
+ if (ret == 0 || ret == -EHWPOISON) {
+ mtk_dram_ecc_record_retired_page(pfn,
+ MTK_DRAM_ECC_RETIRE_CE,
+ ret);
+ retired = true;
+ } else {
+ pr_warn_ratelimited("mtk-dram-ecc: CE page isolation failed: pfn=0x%llx ret=%d\n",
+ pfn, ret);
+ }
+ }
+
+ trace_mtk_dram_ecc_page_retire(pfn, count, mtk_ecc_data.lb_threshold,
+ retired);
+}
+
+/* ------------------------------------------------------------------ */
+/* sysfs */
+/* ------------------------------------------------------------------ */
+
+static struct kobject *leaky_bucket_kobj;
+
+#define MTK_ECC_LB_THRESHOLD_MAX 10000U
+#define MTK_ECC_LB_DECAY_INTERVAL_MAX 86400U
+#define MTK_ECC_LB_MAX_TRACKED_MAX 16U
+
+static ssize_t threshold_show(struct kobject *kobj, struct kobj_attribute *attr,
+ char *buf)
+{
+ return sysfs_emit(buf, "%u\n", mtk_ecc_data.lb_threshold);
+}
+
+static ssize_t threshold_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ u32 val;
+ int ret;
+
+ ret = kstrtou32(buf, 0, &val);
+ if (ret)
+ return ret;
+ if (val == 0)
+ val = MTK_ECC_LB_THRESHOLD_DEFAULT;
+ else if (val > MTK_ECC_LB_THRESHOLD_MAX)
+ return -EINVAL;
+
+ mtk_ecc_data.lb_threshold = val;
+ return count;
+}
+
+static ssize_t decay_interval_sec_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", mtk_ecc_data.lb_decay_interval_sec);
+}
+
+static ssize_t decay_interval_sec_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ u32 val;
+ int ret;
+
+ ret = kstrtou32(buf, 0, &val);
+ if (ret)
+ return ret;
+ if (val == 0)
+ val = MTK_ECC_LB_DECAY_INTERVAL_DEFAULT;
+ else if (val > MTK_ECC_LB_DECAY_INTERVAL_MAX)
+ return -EINVAL;
+
+ mtk_ecc_data.lb_decay_interval_sec = val;
+ return count;
+}
+
+static ssize_t max_tracked_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", mtk_ecc_data.lb_max_tracked);
+}
+
+static ssize_t max_tracked_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ u32 val;
+ int ret;
+
+ ret = kstrtou32(buf, 0, &val);
+ if (ret)
+ return ret;
+ if (val == 0)
+ val = MTK_ECC_LB_MAX_TRACKED_DEFAULT;
+ else if (val > MTK_ECC_LB_MAX_TRACKED_MAX)
+ return -EINVAL;
+
+ mtk_ecc_data.lb_max_tracked = val;
+ return count;
+}
+
+static struct kobj_attribute threshold_attr =
+ __ATTR(threshold, 0644, threshold_show, threshold_store);
+static struct kobj_attribute decay_interval_sec_attr =
+ __ATTR(decay_interval_sec, 0644, decay_interval_sec_show, decay_interval_sec_store);
+static struct kobj_attribute max_tracked_attr =
+ __ATTR(max_tracked, 0644, max_tracked_show, max_tracked_store);
+
+static struct attribute *attrs[] = {
+ &threshold_attr.attr,
+ &decay_interval_sec_attr.attr,
+ &max_tracked_attr.attr,
+ NULL,
+};
+
+static const struct attribute_group group = {
+ .attrs = attrs,
+};
+
+/* ------------------------------------------------------------------ */
+/* init / exit */
+/* ------------------------------------------------------------------ */
+
+int leaky_bucket_init(struct kobject *parent)
+{
+ int ret;
+
+ hash_init(lb_table);
+ INIT_DELAYED_WORK(&lb_decay_work, lb_decay_fn);
+
+ leaky_bucket_kobj = kobject_create_and_add("leaky_bucket", parent);
+ if (!leaky_bucket_kobj)
+ return -ENOMEM;
+
+ ret = sysfs_create_group(leaky_bucket_kobj, &group);
+ if (ret) {
+ kobject_put(leaky_bucket_kobj);
+ return ret;
+ }
+ return 0;
+}
+
+void leaky_bucket_exit(struct kobject *parent)
+{
+ struct lb_entry *e;
+ struct hlist_node *tmp;
+ unsigned int bkt;
+
+ cancel_delayed_work_sync(&lb_decay_work);
+
+ spin_lock(&lb_lock);
+ hash_for_each_safe(lb_table, bkt, tmp, e, node) {
+ hash_del(&e->node);
+ kfree(e);
+ }
+ lb_tracked = 0;
+ spin_unlock(&lb_lock);
+
+ sysfs_remove_group(leaky_bucket_kobj, &group);
+ kobject_put(leaky_bucket_kobj);
+}
diff --git a/drivers/soc/mediatek/dram-ecc/core/policy/policy.c b/drivers/soc/mediatek/dram-ecc/core/policy/policy.c
index ecd0a430de6d..5a4181b8de7d 100644
--- a/drivers/soc/mediatek/dram-ecc/core/policy/policy.c
+++ b/drivers/soc/mediatek/dram-ecc/core/policy/policy.c
@@ -26,12 +26,18 @@ int mtk_dram_ecc_policy_init(struct device *dev)
if (ret)
goto err_containment;
- ret = address_range_init(policy_kobj);
+ ret = leaky_bucket_init(policy_kobj);
if (ret)
goto err_storm;
+ ret = address_range_init(policy_kobj);
+ if (ret)
+ goto err_leaky_bucket;
+
return 0;
+err_leaky_bucket:
+ leaky_bucket_exit(policy_kobj);
err_storm:
storm_protection_exit(policy_kobj);
err_containment:
@@ -44,6 +50,7 @@ int mtk_dram_ecc_policy_init(struct device *dev)
void mtk_dram_ecc_policy_exit(struct device *dev)
{
address_range_exit(policy_kobj);
+ leaky_bucket_exit(policy_kobj);
storm_protection_exit(policy_kobj);
containment_exit(policy_kobj);
kobject_put(policy_kobj);
diff --git a/drivers/soc/mediatek/dram-ecc/core/policy/policy.h b/drivers/soc/mediatek/dram-ecc/core/policy/policy.h
index a535e2ce0e6d..c9926cbc11be 100644
--- a/drivers/soc/mediatek/dram-ecc/core/policy/policy.h
+++ b/drivers/soc/mediatek/dram-ecc/core/policy/policy.h
@@ -13,6 +13,10 @@ void containment_exit(struct kobject *parent);
int storm_protection_init(struct kobject *parent);
void storm_protection_exit(struct kobject *parent);
+int leaky_bucket_init(struct kobject *parent);
+void leaky_bucket_exit(struct kobject *parent);
+void leaky_bucket_hit(u64 spa);
+
int address_range_init(struct kobject *parent);
void address_range_exit(struct kobject *parent);
--
2.45.2
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