Break down the system-wide working set reporting into
per-memcg reports, which aggregages its children hierarchically.
The per-node working set reporting histograms and refresh/report
threshold files are presented as memcg files, showing a report
containing all the nodes.

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.page_age_intervals
        Configures the intervals for the page age histogram. This file
        operates on a per-node basis, allowing for different intervals
        for each node.
        e.g.
        echo N0=1000,2000,3000,4000,5000 > memory.workingset.page_age_intervals

/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 <[email protected]>
---
 include/linux/memcontrol.h        |   5 +
 include/linux/workingset_report.h |   6 +-
 mm/internal.h                     |   2 +
 mm/memcontrol.c                   | 267 +++++++++++++++++++++++++++++-
 mm/workingset_report.c            |  10 +-
 5 files changed, 286 insertions(+), 4 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 20ff87f8e001..7d7bc0928961 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -335,6 +335,11 @@ struct mem_cgroup {
        struct lru_gen_mm_list mm_list;
 #endif
 
+#ifdef CONFIG_WORKINGSET_REPORT
+       /* memory.workingset.page_age file */
+       struct cgroup_file workingset_page_age_file;
+#endif
+
        struct mem_cgroup_per_node *nodeinfo[];
 };
 
diff --git a/include/linux/workingset_report.h 
b/include/linux/workingset_report.h
index 589d240d6251..502542c812b3 100644
--- a/include/linux/workingset_report.h
+++ b/include/linux/workingset_report.h
@@ -9,6 +9,7 @@ struct mem_cgroup;
 struct pglist_data;
 struct node;
 struct lruvec;
+struct cgroup_file;
 
 #ifdef CONFIG_WORKINGSET_REPORT
 
@@ -38,7 +39,10 @@ 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;
diff --git a/mm/internal.h b/mm/internal.h
index 36480c7ac0dd..3730c8399ad4 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -212,6 +212,8 @@ extern void reclaim_throttle(pg_data_t *pgdat, enum 
vmscan_throttle_state reason
 void notify_workingset(struct mem_cgroup *memcg, struct pglist_data *pgdat);
 /* Requires wsr->page_age_lock held */
 void wsr_refresh_scan(struct lruvec *lruvec, unsigned long refresh_interval);
+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 2f07141de16c..75bda5f7994d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7005,6 +7005,245 @@ static ssize_t memory_reclaim(struct kernfs_open_file 
*of, char *buf,
        return nbytes;
 }
 
+#ifdef CONFIG_WORKINGSET_REPORT
+static int memory_ws_page_age_intervals_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;
+               struct wsr_page_age_histo *page_age;
+               int i, nr_bins;
+
+               wsr = &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+               mutex_lock(&wsr->page_age_lock);
+               page_age = wsr->page_age;
+               if (!page_age)
+                       goto no_page_age;
+               seq_printf(m, "N%d=", nid);
+               nr_bins = page_age->bins.nr_bins;
+               for (i = 0; i < nr_bins; ++i) {
+                       struct wsr_report_bin *bin =
+                               &page_age->bins.bins[i];
+
+                       seq_printf(m, "%u", jiffies_to_msecs(bin->idle_age));
+                       if (i + 1 < nr_bins)
+                               seq_putc(m, ',');
+               }
+               seq_putc(m, ' ');
+no_page_age:
+               mutex_unlock(&wsr->page_age_lock);
+       }
+       seq_putc(m, '\n');
+
+       return 0;
+}
+
+static ssize_t memory_wsr_interval_parse(struct kernfs_open_file *of, char 
*buf,
+                                        size_t nbytes, unsigned int *nid_out,
+                                        struct wsr_report_bins *bins)
+{
+       char *node, *intervals;
+       unsigned int nid;
+       int err;
+
+       buf = strstrip(buf);
+       intervals = buf;
+       node = strsep(&intervals, "=");
+
+       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 = workingset_report_intervals_parse(intervals, bins);
+       if (err < 0)
+               return err;
+
+       *nid_out = nid;
+       return err;
+}
+
+static ssize_t memory_ws_page_age_intervals_write(struct kernfs_open_file *of,
+                                                 char *buf, size_t nbytes,
+                                                 loff_t off)
+{
+       unsigned int nid;
+       int err;
+       struct wsr_page_age_histo *page_age = NULL, *old;
+       struct wsr_state *wsr;
+       struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
+
+       page_age =
+               kzalloc(sizeof(struct wsr_page_age_histo), GFP_KERNEL_ACCOUNT);
+
+       if (!page_age) {
+               err = -ENOMEM;
+               goto failed;
+       }
+
+       err = memory_wsr_interval_parse(of, buf, nbytes, &nid, &page_age->bins);
+       if (err < 0)
+               goto failed;
+
+       if (err == 0) {
+               kfree(page_age);
+               page_age = NULL;
+       }
+
+       wsr = &mem_cgroup_lruvec(memcg, NODE_DATA(nid))->wsr;
+       mutex_lock(&wsr->page_age_lock);
+       old = xchg(&wsr->page_age, page_age);
+       mutex_unlock(&wsr->page_age_lock);
+       kfree(old);
+       return nbytes;
+failed:
+       kfree(page_age);
+       return err;
+}
+
+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;
+       WRITE_ONCE(wsr->refresh_interval, msecs_to_jiffies(msecs));
+       return ret;
+}
+
+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.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",
@@ -7073,7 +7312,33 @@ static struct cftype memory_files[] = {
                .flags = CFTYPE_NS_DELEGATABLE,
                .write = memory_reclaim,
        },
-       { }     /* terminate */
+#ifdef CONFIG_WORKINGSET_REPORT
+       {
+               .name = "workingset.page_age_intervals",
+               .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_NS_DELEGATABLE,
+               .seq_show = memory_ws_page_age_intervals_show,
+               .write = memory_ws_page_age_intervals_write,
+       },
+       {
+               .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 3ed3b0e8f8ad..b00ffbfebcab 100644
--- a/mm/workingset_report.c
+++ b/mm/workingset_report.c
@@ -20,9 +20,12 @@
 void wsr_init(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 = &memcg->workingset_page_age_file;
 }
 
 void wsr_destroy(struct lruvec *lruvec)
@@ -34,7 +37,7 @@ void wsr_destroy(struct lruvec *lruvec)
        memset(wsr, 0, sizeof(*wsr));
 }
 
-static int workingset_report_intervals_parse(char *src,
+int workingset_report_intervals_parse(char *src,
                                      struct wsr_report_bins *bins)
 {
        int err = 0, i = 0;
@@ -490,5 +493,8 @@ 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);
 }
-- 
2.44.0.396.g6e790dbe36-goog


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