6 files changed, 115 insertions, 0 deletions

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 3e579740b49f..055c8b3e1018 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -58,6 +58,7 @@ Currently, these files are in /proc/sys/vm:
 - percpu_pagelist_fraction
 - stat_interval
 - stat_refresh
+- numa_stat
 - swappiness
 - user_reserve_kbytes
 - vfs_cache_pressure
@@ -799,6 +800,21 @@ with no ill effects: errors and warnings on these stats are suppressed.)
 
 ==============================================================
 
+numa_stat
+
+This interface allows runtime configuration of numa statistics.
+
+When page allocation performance becomes a bottleneck and you can tolerate
+some possible tool breakage and decreased numa counter precision, you can
+do:
+        echo 0 > /proc/sys/vm/numa_stat
+
+When page allocation performance is not a bottleneck and you want all
+tooling to work, you can do:
+        echo 1 > /proc/sys/vm/numa_stat
+
+==============================================================
+
 swappiness
 
 This control is used to define how aggressive the kernel will swap
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 1e0cb72e0598..1779c9817b39 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -7,9 +7,19 @@
 #include <linux/mmzone.h>
 #include <linux/vm_event_item.h>
 #include <linux/atomic.h>
+#include <linux/static_key.h>
 
 extern int sysctl_stat_interval;
 
+#ifdef CONFIG_NUMA
+#define ENABLE_NUMA_STAT   1
+#define DISABLE_NUMA_STAT   0
+extern int sysctl_vm_numa_stat;
+DECLARE_STATIC_KEY_TRUE(vm_numa_stat_key);
+extern int sysctl_vm_numa_stat_handler(struct ctl_table *table,
+                int write, void __user *buffer, size_t *length, loff_t *ppos);
+#endif
+
 #ifdef CONFIG_VM_EVENT_COUNTERS
 /*
  * Light weight per cpu counter implementation.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 7638e2f7fff8..4a13a389e99b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1356,6 +1356,15 @@ static struct ctl_table vm_table[] = {
                 .mode           = 0644,
                 .proc_handler   = &hugetlb_mempolicy_sysctl_handler,
         },
+        {
+                .procname               = "numa_stat",
+                .data                   = &sysctl_vm_numa_stat,
+                .maxlen                 = sizeof(int),
+                .mode                   = 0644,
+                .proc_handler   = sysctl_vm_numa_stat_handler,
+                .extra1                 = &zero,
+                .extra2                 = &one,
+        },
 #endif
          {
                 .procname       = "hugetlb_shm_group",
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index dad166b736ba..4ce44d3ff03d 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1915,6 +1915,9 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
         struct page *page;
 
         page = __alloc_pages(gfp, order, nid);
+        /* skip NUMA_INTERLEAVE_HIT counter update if numa stats is disabled */
+        if (!static_branch_likely(&vm_numa_stat_key))
+                return page;
         if (page && page_to_nid(page) == nid) {
                 preempt_disable();
                 __inc_numa_state(page_zone(page), NUMA_INTERLEAVE_HIT);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7ca668e946e5..67f523c4711a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -82,6 +82,8 @@ DEFINE_PER_CPU(int, numa_node);
 EXPORT_PER_CPU_SYMBOL(numa_node);
 #endif
 
+DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key);
+
 #ifdef CONFIG_HAVE_MEMORYLESS_NODES
 /*
  * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
@@ -2777,6 +2779,10 @@ static inline void zone_statistics(struct zone *preferred_zone, struct zone *z)
 #ifdef CONFIG_NUMA
         enum numa_stat_item local_stat = NUMA_LOCAL;
 
+        /* skip numa counters update if numa stats is disabled */
+        if (!static_branch_likely(&vm_numa_stat_key))
+                return;
+
         if (z->node != numa_node_id())
                 local_stat = NUMA_OTHER;
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 7d11554861e4..40b2db6db6b1 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -32,6 +32,77 @@
 
 #define NUMA_STATS_THRESHOLD (U16_MAX - 2)
 
+#ifdef CONFIG_NUMA
+int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
+
+/* zero numa counters within a zone */
+static void zero_zone_numa_counters(struct zone *zone)
+{
+        int item, cpu;
+
+        for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++) {
+                atomic_long_set(&zone->vm_numa_stat[item], 0);
+                for_each_online_cpu(cpu)
+                        per_cpu_ptr(zone->pageset, cpu)->vm_numa_stat_diff[item]
+                                                = 0;
+        }
+}
+
+/* zero numa counters of all the populated zones */
+static void zero_zones_numa_counters(void)
+{
+        struct zone *zone;
+
+        for_each_populated_zone(zone)
+                zero_zone_numa_counters(zone);
+}
+
+/* zero global numa counters */
+static void zero_global_numa_counters(void)
+{
+        int item;
+
+        for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++)
+                atomic_long_set(&vm_numa_stat[item], 0);
+}
+
+static void invalid_numa_statistics(void)
+{
+        zero_zones_numa_counters();
+        zero_global_numa_counters();
+}
+
+static DEFINE_MUTEX(vm_numa_stat_lock);
+
+int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
+                void __user *buffer, size_t *length, loff_t *ppos)
+{
+        int ret, oldval;
+
+        mutex_lock(&vm_numa_stat_lock);
+        if (write)
+                oldval = sysctl_vm_numa_stat;
+        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+        if (ret || !write)
+                goto out;
+
+        if (oldval == sysctl_vm_numa_stat)
+                goto out;
+        else if (sysctl_vm_numa_stat == ENABLE_NUMA_STAT) {
+                static_branch_enable(&vm_numa_stat_key);
+                pr_info("enable numa statistics\n");
+        } else {
+                static_branch_disable(&vm_numa_stat_key);
+                invalid_numa_statistics();
+                pr_info("disable numa statistics, and clear numa counters\n");
+        }
+
+out:
+        mutex_unlock(&vm_numa_stat_lock);
+        return ret;
+}
+#endif
+
 #ifdef CONFIG_VM_EVENT_COUNTERS
 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
 EXPORT_PER_CPU_SYMBOL(vm_event_states);