Break down the system-wide workingset report into per-memcg reports,
which aggregages its children hierarchically.

The per-node workingset reporting histograms and refresh/report
threshold files are presented as memcg files, showing a report
containing all the nodes.

The per-node page age interval is configurable in sysfs and not
available per-memcg, while the refresh interval and report threshold are
configured per-memcg.

Memcg interface:
/sys/fs/cgroup/.../memory.workingset.page_age
        The memcg equivalent of the sysfs workingset page age histogram
        breaks down the workingset of this memcg and its children into
        page age intervals. Each node is prefixed with a node header and
        a newline. Non-proactive direct reclaim on this memcg can also
        wake up userspace agents that are waiting on this file.
        e.g.
        N0
        1000 anon=0 file=0
        2000 anon=0 file=0
        3000 anon=0 file=0
        4000 anon=0 file=0
        5000 anon=0 file=0
        18446744073709551615 anon=0 file=0

/sys/fs/cgroup/.../memory.workingset.refresh_interval
        The memcg equivalent of the sysfs refresh interval. A per-node
        number of how much time a page age histogram is valid for, in
        milliseconds.
        e.g.
        echo N0=2000 > memory.workingset.refresh_interval

/sys/fs/cgroup/.../memory.workingset.report_threshold
        The memcg equivalent of the sysfs report threshold. A per-node
        number of how often userspace agent waiting on the page age
        histogram can be woken up, in milliseconds.
        e.g.
        echo N0=1000 > memory.workingset.report_threshold

Signed-off-by: Yuanchu Xie <yuan...@google.com>
---
 include/linux/memcontrol.h        |  21 ++++
 include/linux/workingset_report.h |  15 ++-
 mm/internal.h                     |   2 +
 mm/memcontrol.c                   | 160 +++++++++++++++++++++++++++++-
 mm/workingset_report.c            |  50 +++++++---
 5 files changed, 230 insertions(+), 18 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e1b41554a5fb..fd595b33a54d 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -323,6 +323,11 @@ struct mem_cgroup {
        spinlock_t event_list_lock;
 #endif /* CONFIG_MEMCG_V1 */
 
+#ifdef CONFIG_WORKINGSET_REPORT
+       /* memory.workingset.page_age file */
+       struct cgroup_file workingset_page_age_file;
+#endif
+
        struct mem_cgroup_per_node *nodeinfo[];
 };
 
@@ -1094,6 +1099,16 @@ static inline void memcg_memory_event_mm(struct 
mm_struct *mm,
 
 void split_page_memcg(struct page *head, int old_order, int new_order);
 
+static inline struct cgroup_file *
+mem_cgroup_page_age_file(struct mem_cgroup *memcg)
+{
+#ifdef CONFIG_WORKINGSET_REPORT
+       return &memcg->workingset_page_age_file;
+#else
+       return NULL;
+#endif
+}
+
 #else /* CONFIG_MEMCG */
 
 #define MEM_CGROUP_ID_SHIFT    0
@@ -1511,6 +1526,12 @@ void count_memcg_event_mm(struct mm_struct *mm, enum 
vm_event_item idx)
 static inline void split_page_memcg(struct page *head, int old_order, int 
new_order)
 {
 }
+
+static inline struct cgroup_file *
+mem_cgroup_page_age_file(struct mem_cgroup *memcg)
+{
+       return NULL;
+}
 #endif /* CONFIG_MEMCG */
 
 /*
diff --git a/include/linux/workingset_report.h 
b/include/linux/workingset_report.h
index 2ec8b927b200..616be6469768 100644
--- a/include/linux/workingset_report.h
+++ b/include/linux/workingset_report.h
@@ -9,6 +9,8 @@ struct mem_cgroup;
 struct pglist_data;
 struct node;
 struct lruvec;
+struct cgroup_file;
+struct wsr_state;
 
 #ifdef CONFIG_WORKINGSET_REPORT
 
@@ -40,7 +42,10 @@ struct wsr_state {
        unsigned long report_threshold;
        unsigned long refresh_interval;
 
-       struct kernfs_node *page_age_sys_file;
+       union {
+               struct kernfs_node *page_age_sys_file;
+               struct cgroup_file *page_age_cgroup_file;
+       };
 
        /* breakdown of workingset by page age */
        struct mutex page_age_lock;
@@ -60,6 +65,9 @@ void wsr_remove_sysfs(struct node *node);
  */
 bool wsr_refresh_report(struct wsr_state *wsr, struct mem_cgroup *root,
                        struct pglist_data *pgdat);
+
+int wsr_set_refresh_interval(struct wsr_state *wsr,
+                            unsigned long refresh_interval);
 #else
 static inline void wsr_init_lruvec(struct lruvec *lruvec)
 {
@@ -79,6 +87,11 @@ static inline void wsr_init_sysfs(struct node *node)
 static inline void wsr_remove_sysfs(struct node *node)
 {
 }
+static inline int wsr_set_refresh_interval(struct wsr_state *wsr,
+                                          unsigned long refresh_interval)
+{
+       return 0;
+}
 #endif /* CONFIG_WORKINGSET_REPORT */
 
 #endif /* _LINUX_WORKINGSET_REPORT_H */
diff --git a/mm/internal.h b/mm/internal.h
index 508b7d9937d6..50ca0c6e651c 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -484,6 +484,8 @@ void set_task_reclaim_state(struct task_struct *task, 
struct reclaim_state *rs);
  * in mm/wsr.c
  */
 void notify_workingset(struct mem_cgroup *memcg, struct pglist_data *pgdat);
+int workingset_report_intervals_parse(char *src,
+                                     struct wsr_report_bins *bins);
 #else
 static inline void notify_workingset(struct mem_cgroup *memcg,
                                     struct pglist_data *pgdat)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 096856b35fbc..d1032c6efc66 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4348,6 +4348,144 @@ static ssize_t memory_reclaim(struct kernfs_open_file 
*of, char *buf,
        return nbytes;
 }
 
+#ifdef CONFIG_WORKINGSET_REPORT
+static int memory_ws_refresh_interval_show(struct seq_file *m, void *v)
+{
+       int nid;
+       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+       for_each_node_state(nid, N_MEMORY) {
+               struct wsr_state *wsr =
+                       &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+
+               seq_printf(m, "N%d=%u ", nid,
+                          jiffies_to_msecs(READ_ONCE(wsr->refresh_interval)));
+       }
+       seq_putc(m, '\n');
+
+       return 0;
+}
+
+static ssize_t memory_wsr_threshold_parse(char *buf, size_t nbytes,
+                                         unsigned int *nid_out,
+                                         unsigned int *msecs)
+{
+       char *node, *threshold;
+       unsigned int nid;
+       int err;
+
+       buf = strstrip(buf);
+       threshold = buf;
+       node = strsep(&threshold, "=");
+
+       if (*node != 'N')
+               return -EINVAL;
+
+       err = kstrtouint(node + 1, 0, &nid);
+       if (err)
+               return err;
+
+       if (nid >= nr_node_ids || !node_state(nid, N_MEMORY))
+               return -EINVAL;
+
+       err = kstrtouint(threshold, 0, msecs);
+       if (err)
+               return err;
+
+       *nid_out = nid;
+
+       return nbytes;
+}
+
+static ssize_t memory_ws_refresh_interval_write(struct kernfs_open_file *of,
+                                                char *buf, size_t nbytes,
+                                                loff_t off)
+{
+       unsigned int nid, msecs;
+       struct wsr_state *wsr;
+       struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+       ssize_t ret = memory_wsr_threshold_parse(buf, nbytes, &nid, &msecs);
+
+       if (ret < 0)
+               return ret;
+
+       wsr = &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+
+       ret = wsr_set_refresh_interval(wsr, msecs);
+       return ret ?: nbytes;
+}
+
+static int memory_ws_report_threshold_show(struct seq_file *m, void *v)
+{
+       int nid;
+       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+       for_each_node_state(nid, N_MEMORY) {
+               struct wsr_state *wsr =
+                       &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+
+               seq_printf(m, "N%d=%u ", nid,
+                          jiffies_to_msecs(READ_ONCE(wsr->report_threshold)));
+       }
+       seq_putc(m, '\n');
+
+       return 0;
+}
+
+static ssize_t memory_ws_report_threshold_write(struct kernfs_open_file *of,
+                                                char *buf, size_t nbytes,
+                                                loff_t off)
+{
+       unsigned int nid, msecs;
+       struct wsr_state *wsr;
+       struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+       ssize_t ret = memory_wsr_threshold_parse(buf, nbytes, &nid, &msecs);
+
+       if (ret < 0)
+               return ret;
+
+       wsr = &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+       WRITE_ONCE(wsr->report_threshold, msecs_to_jiffies(msecs));
+       return ret;
+}
+
+static int memory_ws_page_age_show(struct seq_file *m, void *v)
+{
+       int nid;
+       struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
+
+       for_each_node_state(nid, N_MEMORY) {
+               struct wsr_state *wsr =
+                       &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+               struct wsr_report_bin *bin;
+
+               if (!READ_ONCE(wsr->page_age))
+                       continue;
+
+               wsr_refresh_report(wsr, memcg, NODE_DATA(nid));
+               mutex_lock(&wsr->page_age_lock);
+               if (!wsr->page_age)
+                       goto unlock;
+               seq_printf(m, "N%d\n", nid);
+               for (bin = wsr->page_age->bins;
+                    bin->idle_age != WORKINGSET_INTERVAL_MAX; bin++)
+                       seq_printf(m, "%u anon=%lu file=%lu\n",
+                                  jiffies_to_msecs(bin->idle_age),
+                                  bin->nr_pages[0] * PAGE_SIZE,
+                                  bin->nr_pages[1] * PAGE_SIZE);
+
+               seq_printf(m, "%lu anon=%lu file=%lu\n", 
WORKINGSET_INTERVAL_MAX,
+                          bin->nr_pages[0] * PAGE_SIZE,
+                          bin->nr_pages[1] * PAGE_SIZE);
+
+unlock:
+               mutex_unlock(&wsr->page_age_lock);
+       }
+
+       return 0;
+}
+#endif
+
 static struct cftype memory_files[] = {
        {
                .name = "current",
@@ -4419,7 +4557,27 @@ static struct cftype memory_files[] = {
                .flags = CFTYPE_NS_DELEGATABLE,
                .write = memory_reclaim,
        },
-       { }     /* terminate */
+#ifdef CONFIG_WORKINGSET_REPORT
+       {
+               .name = "workingset.refresh_interval",
+               .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+               .seq_show = memory_ws_refresh_interval_show,
+               .write = memory_ws_refresh_interval_write,
+       },
+       {
+               .name = "workingset.report_threshold",
+               .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+               .seq_show = memory_ws_report_threshold_show,
+               .write = memory_ws_report_threshold_write,
+       },
+       {
+               .name = "workingset.page_age",
+               .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+               .file_offset = offsetof(struct mem_cgroup, 
workingset_page_age_file),
+               .seq_show = memory_ws_page_age_show,
+       },
+#endif
+       {} /* terminate */
 };
 
 struct cgroup_subsys memory_cgrp_subsys = {
diff --git a/mm/workingset_report.c b/mm/workingset_report.c
index bbefb0046669..1e1bdb8bf75b 100644
--- a/mm/workingset_report.c
+++ b/mm/workingset_report.c
@@ -37,9 +37,12 @@ void wsr_destroy_pgdat(struct pglist_data *pgdat)
 void wsr_init_lruvec(struct lruvec *lruvec)
 {
        struct wsr_state *wsr = &lruvec->wsr;
+       struct mem_cgroup *memcg = lruvec_memcg(lruvec);
 
        memset(wsr, 0, sizeof(*wsr));
        mutex_init(&wsr->page_age_lock);
+       if (memcg && !mem_cgroup_is_root(memcg))
+               wsr->page_age_cgroup_file = mem_cgroup_page_age_file(memcg);
 }
 
 void wsr_destroy_lruvec(struct lruvec *lruvec)
@@ -51,8 +54,8 @@ void wsr_destroy_lruvec(struct lruvec *lruvec)
        memset(wsr, 0, sizeof(*wsr));
 }
 
-static int workingset_report_intervals_parse(char *src,
-                                            struct wsr_report_bins *bins)
+int workingset_report_intervals_parse(char *src,
+                                     struct wsr_report_bins *bins)
 {
        int err = 0, i = 0;
        char *cur, *next = strim(src);
@@ -356,20 +359,14 @@ static ssize_t refresh_interval_show(struct kobject *kobj,
        return sysfs_emit(buf, "%u\n", jiffies_to_msecs(interval));
 }
 
-static ssize_t refresh_interval_store(struct kobject *kobj,
-                                     struct kobj_attribute *attr,
-                                     const char *buf, size_t len)
+int wsr_set_refresh_interval(struct wsr_state *wsr,
+                            unsigned long refresh_interval)
 {
-       unsigned int interval;
-       int err;
-       struct wsr_state *wsr = kobj_to_wsr(kobj);
-
-       err = kstrtouint(buf, 0, &interval);
-       if (err)
-               return err;
+       int err = 0;
+       unsigned long old_interval = 0;
 
        mutex_lock(&wsr->page_age_lock);
-       if (interval && !wsr->page_age) {
+       if (refresh_interval && !wsr->page_age) {
                struct wsr_page_age_histo *page_age =
                        kzalloc(sizeof(struct wsr_page_age_histo), GFP_KERNEL);
 
@@ -377,16 +374,34 @@ static ssize_t refresh_interval_store(struct kobject 
*kobj,
                        err = -ENOMEM;
                        goto unlock;
                }
+               page_age->bins[0].idle_age = WORKINGSET_INTERVAL_MAX;
                wsr->page_age = page_age;
        }
-       if (!interval && wsr->page_age) {
+       if (!refresh_interval && wsr->page_age) {
                kfree(wsr->page_age);
                wsr->page_age = NULL;
        }
 
-       WRITE_ONCE(wsr->refresh_interval, msecs_to_jiffies(interval));
+       old_interval = READ_ONCE(wsr->refresh_interval);
+       WRITE_ONCE(wsr->refresh_interval, msecs_to_jiffies(refresh_interval));
 unlock:
        mutex_unlock(&wsr->page_age_lock);
+       return err;
+}
+
+static ssize_t refresh_interval_store(struct kobject *kobj,
+                                     struct kobj_attribute *attr,
+                                     const char *buf, size_t len)
+{
+       unsigned int interval;
+       int err;
+       struct wsr_state *wsr = kobj_to_wsr(kobj);
+
+       err = kstrtouint(buf, 0, &interval);
+       if (err)
+               return err;
+
+       err = wsr_set_refresh_interval(wsr, interval);
        return err ?: len;
 }
 
@@ -551,5 +566,8 @@ void notify_workingset(struct mem_cgroup *memcg, struct 
pglist_data *pgdat)
 {
        struct wsr_state *wsr = &mem_cgroup_lruvec(memcg, pgdat)->wsr;
 
-       kernfs_notify(wsr->page_age_sys_file);
+       if (mem_cgroup_is_root(memcg))
+               kernfs_notify(wsr->page_age_sys_file);
+       else
+               cgroup_file_notify(wsr->page_age_cgroup_file);
 }
-- 
2.47.0.338.g60cca15819-goog


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