v4.19.13 snapshot.
diff --git a/mm/percpu-stats.c b/mm/percpu-stats.c
new file mode 100644
index 0000000..b5fdd43
--- /dev/null
+++ b/mm/percpu-stats.c
@@ -0,0 +1,236 @@
+/*
+ * mm/percpu-debug.c
+ *
+ * Copyright (C) 2017 Facebook Inc.
+ * Copyright (C) 2017 Dennis Zhou <dennisz@fb.com>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Prints statistics about the percpu allocator and backing chunks.
+ */
+#include <linux/debugfs.h>
+#include <linux/list.h>
+#include <linux/percpu.h>
+#include <linux/seq_file.h>
+#include <linux/sort.h>
+#include <linux/vmalloc.h>
+
+#include "percpu-internal.h"
+
+#define P(X, Y) \
+ seq_printf(m, " %-20s: %12lld\n", X, (long long int)Y)
+
+struct percpu_stats pcpu_stats;
+struct pcpu_alloc_info pcpu_stats_ai;
+
+static int cmpint(const void *a, const void *b)
+{
+ return *(int *)a - *(int *)b;
+}
+
+/*
+ * Iterates over all chunks to find the max nr_alloc entries.
+ */
+static int find_max_nr_alloc(void)
+{
+ struct pcpu_chunk *chunk;
+ int slot, max_nr_alloc;
+
+ max_nr_alloc = 0;
+ for (slot = 0; slot < pcpu_nr_slots; slot++)
+ list_for_each_entry(chunk, &pcpu_slot[slot], list)
+ max_nr_alloc = max(max_nr_alloc, chunk->nr_alloc);
+
+ return max_nr_alloc;
+}
+
+/*
+ * Prints out chunk state. Fragmentation is considered between
+ * the beginning of the chunk to the last allocation.
+ *
+ * All statistics are in bytes unless stated otherwise.
+ */
+static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,
+ int *buffer)
+{
+ int i, last_alloc, as_len, start, end;
+ int *alloc_sizes, *p;
+ /* statistics */
+ int sum_frag = 0, max_frag = 0;
+ int cur_min_alloc = 0, cur_med_alloc = 0, cur_max_alloc = 0;
+
+ alloc_sizes = buffer;
+
+ /*
+ * find_last_bit returns the start value if nothing found.
+ * Therefore, we must determine if it is a failure of find_last_bit
+ * and set the appropriate value.
+ */
+ last_alloc = find_last_bit(chunk->alloc_map,
+ pcpu_chunk_map_bits(chunk) -
+ chunk->end_offset / PCPU_MIN_ALLOC_SIZE - 1);
+ last_alloc = test_bit(last_alloc, chunk->alloc_map) ?
+ last_alloc + 1 : 0;
+
+ as_len = 0;
+ start = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
+
+ /*
+ * If a bit is set in the allocation map, the bound_map identifies
+ * where the allocation ends. If the allocation is not set, the
+ * bound_map does not identify free areas as it is only kept accurate
+ * on allocation, not free.
+ *
+ * Positive values are allocations and negative values are free
+ * fragments.
+ */
+ while (start < last_alloc) {
+ if (test_bit(start, chunk->alloc_map)) {
+ end = find_next_bit(chunk->bound_map, last_alloc,
+ start + 1);
+ alloc_sizes[as_len] = 1;
+ } else {
+ end = find_next_bit(chunk->alloc_map, last_alloc,
+ start + 1);
+ alloc_sizes[as_len] = -1;
+ }
+
+ alloc_sizes[as_len++] *= (end - start) * PCPU_MIN_ALLOC_SIZE;
+
+ start = end;
+ }
+
+ /*
+ * The negative values are free fragments and thus sorting gives the
+ * free fragments at the beginning in largest first order.
+ */
+ if (as_len > 0) {
+ sort(alloc_sizes, as_len, sizeof(int), cmpint, NULL);
+
+ /* iterate through the unallocated fragments */
+ for (i = 0, p = alloc_sizes; *p < 0 && i < as_len; i++, p++) {
+ sum_frag -= *p;
+ max_frag = max(max_frag, -1 * (*p));
+ }
+
+ cur_min_alloc = alloc_sizes[i];
+ cur_med_alloc = alloc_sizes[(i + as_len - 1) / 2];
+ cur_max_alloc = alloc_sizes[as_len - 1];
+ }
+
+ P("nr_alloc", chunk->nr_alloc);
+ P("max_alloc_size", chunk->max_alloc_size);
+ P("empty_pop_pages", chunk->nr_empty_pop_pages);
+ P("first_bit", chunk->first_bit);
+ P("free_bytes", chunk->free_bytes);
+ P("contig_bytes", chunk->contig_bits * PCPU_MIN_ALLOC_SIZE);
+ P("sum_frag", sum_frag);
+ P("max_frag", max_frag);
+ P("cur_min_alloc", cur_min_alloc);
+ P("cur_med_alloc", cur_med_alloc);
+ P("cur_max_alloc", cur_max_alloc);
+ seq_putc(m, '\n');
+}
+
+static int percpu_stats_show(struct seq_file *m, void *v)
+{
+ struct pcpu_chunk *chunk;
+ int slot, max_nr_alloc;
+ int *buffer;
+
+alloc_buffer:
+ spin_lock_irq(&pcpu_lock);
+ max_nr_alloc = find_max_nr_alloc();
+ spin_unlock_irq(&pcpu_lock);
+
+ /* there can be at most this many free and allocated fragments */
+ buffer = vmalloc(array_size(sizeof(int), (2 * max_nr_alloc + 1)));
+ if (!buffer)
+ return -ENOMEM;
+
+ spin_lock_irq(&pcpu_lock);
+
+ /* if the buffer allocated earlier is too small */
+ if (max_nr_alloc < find_max_nr_alloc()) {
+ spin_unlock_irq(&pcpu_lock);
+ vfree(buffer);
+ goto alloc_buffer;
+ }
+
+#define PL(X) \
+ seq_printf(m, " %-20s: %12lld\n", #X, (long long int)pcpu_stats_ai.X)
+
+ seq_printf(m,
+ "Percpu Memory Statistics\n"
+ "Allocation Info:\n"
+ "----------------------------------------\n");
+ PL(unit_size);
+ PL(static_size);
+ PL(reserved_size);
+ PL(dyn_size);
+ PL(atom_size);
+ PL(alloc_size);
+ seq_putc(m, '\n');
+
+#undef PL
+
+#define PU(X) \
+ seq_printf(m, " %-20s: %12llu\n", #X, (unsigned long long)pcpu_stats.X)
+
+ seq_printf(m,
+ "Global Stats:\n"
+ "----------------------------------------\n");
+ PU(nr_alloc);
+ PU(nr_dealloc);
+ PU(nr_cur_alloc);
+ PU(nr_max_alloc);
+ PU(nr_chunks);
+ PU(nr_max_chunks);
+ PU(min_alloc_size);
+ PU(max_alloc_size);
+ P("empty_pop_pages", pcpu_nr_empty_pop_pages);
+ seq_putc(m, '\n');
+
+#undef PU
+
+ seq_printf(m,
+ "Per Chunk Stats:\n"
+ "----------------------------------------\n");
+
+ if (pcpu_reserved_chunk) {
+ seq_puts(m, "Chunk: <- Reserved Chunk\n");
+ chunk_map_stats(m, pcpu_reserved_chunk, buffer);
+ }
+
+ for (slot = 0; slot < pcpu_nr_slots; slot++) {
+ list_for_each_entry(chunk, &pcpu_slot[slot], list) {
+ if (chunk == pcpu_first_chunk) {
+ seq_puts(m, "Chunk: <- First Chunk\n");
+ chunk_map_stats(m, chunk, buffer);
+
+
+ } else {
+ seq_puts(m, "Chunk:\n");
+ chunk_map_stats(m, chunk, buffer);
+ }
+
+ }
+ }
+
+ spin_unlock_irq(&pcpu_lock);
+
+ vfree(buffer);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(percpu_stats);
+
+static int __init init_percpu_stats_debugfs(void)
+{
+ debugfs_create_file("percpu_stats", 0444, NULL, NULL,
+ &percpu_stats_fops);
+
+ return 0;
+}
+
+late_initcall(init_percpu_stats_debugfs);