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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /mm/page_owner.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'mm/page_owner.c')
-rw-r--r--mm/page_owner.c726
1 files changed, 726 insertions, 0 deletions
diff --git a/mm/page_owner.c b/mm/page_owner.c
new file mode 100644
index 000000000..2d27f532d
--- /dev/null
+++ b/mm/page_owner.c
@@ -0,0 +1,726 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/debugfs.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/memblock.h>
+#include <linux/stacktrace.h>
+#include <linux/page_owner.h>
+#include <linux/jump_label.h>
+#include <linux/migrate.h>
+#include <linux/stackdepot.h>
+#include <linux/seq_file.h>
+#include <linux/memcontrol.h>
+#include <linux/sched/clock.h>
+
+#include "internal.h"
+
+/*
+ * TODO: teach PAGE_OWNER_STACK_DEPTH (__dump_page_owner and save_stack)
+ * to use off stack temporal storage
+ */
+#define PAGE_OWNER_STACK_DEPTH (16)
+
+struct page_owner {
+ unsigned short order;
+ short last_migrate_reason;
+ gfp_t gfp_mask;
+ depot_stack_handle_t handle;
+ depot_stack_handle_t free_handle;
+ u64 ts_nsec;
+ u64 free_ts_nsec;
+ char comm[TASK_COMM_LEN];
+ pid_t pid;
+ pid_t tgid;
+};
+
+static bool page_owner_enabled __initdata;
+DEFINE_STATIC_KEY_FALSE(page_owner_inited);
+
+static depot_stack_handle_t dummy_handle;
+static depot_stack_handle_t failure_handle;
+static depot_stack_handle_t early_handle;
+
+static void init_early_allocated_pages(void);
+
+static int __init early_page_owner_param(char *buf)
+{
+ int ret = kstrtobool(buf, &page_owner_enabled);
+
+ if (page_owner_enabled)
+ stack_depot_want_early_init();
+
+ return ret;
+}
+early_param("page_owner", early_page_owner_param);
+
+static __init bool need_page_owner(void)
+{
+ return page_owner_enabled;
+}
+
+static __always_inline depot_stack_handle_t create_dummy_stack(void)
+{
+ unsigned long entries[4];
+ unsigned int nr_entries;
+
+ nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+ return stack_depot_save(entries, nr_entries, GFP_KERNEL);
+}
+
+static noinline void register_dummy_stack(void)
+{
+ dummy_handle = create_dummy_stack();
+}
+
+static noinline void register_failure_stack(void)
+{
+ failure_handle = create_dummy_stack();
+}
+
+static noinline void register_early_stack(void)
+{
+ early_handle = create_dummy_stack();
+}
+
+static __init void init_page_owner(void)
+{
+ if (!page_owner_enabled)
+ return;
+
+ register_dummy_stack();
+ register_failure_stack();
+ register_early_stack();
+ static_branch_enable(&page_owner_inited);
+ init_early_allocated_pages();
+}
+
+struct page_ext_operations page_owner_ops = {
+ .size = sizeof(struct page_owner),
+ .need = need_page_owner,
+ .init = init_page_owner,
+};
+
+static inline struct page_owner *get_page_owner(struct page_ext *page_ext)
+{
+ return (void *)page_ext + page_owner_ops.offset;
+}
+
+static noinline depot_stack_handle_t save_stack(gfp_t flags)
+{
+ unsigned long entries[PAGE_OWNER_STACK_DEPTH];
+ depot_stack_handle_t handle;
+ unsigned int nr_entries;
+
+ /*
+ * Avoid recursion.
+ *
+ * Sometimes page metadata allocation tracking requires more
+ * memory to be allocated:
+ * - when new stack trace is saved to stack depot
+ * - when backtrace itself is calculated (ia64)
+ */
+ if (current->in_page_owner)
+ return dummy_handle;
+ current->in_page_owner = 1;
+
+ nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
+ handle = stack_depot_save(entries, nr_entries, flags);
+ if (!handle)
+ handle = failure_handle;
+
+ current->in_page_owner = 0;
+ return handle;
+}
+
+void __reset_page_owner(struct page *page, unsigned short order)
+{
+ int i;
+ struct page_ext *page_ext;
+ depot_stack_handle_t handle;
+ struct page_owner *page_owner;
+ u64 free_ts_nsec = local_clock();
+
+ page_ext = page_ext_get(page);
+ if (unlikely(!page_ext))
+ return;
+
+ handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
+ for (i = 0; i < (1 << order); i++) {
+ __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
+ page_owner = get_page_owner(page_ext);
+ page_owner->free_handle = handle;
+ page_owner->free_ts_nsec = free_ts_nsec;
+ page_ext = page_ext_next(page_ext);
+ }
+ page_ext_put(page_ext);
+}
+
+static inline void __set_page_owner_handle(struct page_ext *page_ext,
+ depot_stack_handle_t handle,
+ unsigned short order, gfp_t gfp_mask)
+{
+ struct page_owner *page_owner;
+ int i;
+
+ for (i = 0; i < (1 << order); i++) {
+ page_owner = get_page_owner(page_ext);
+ page_owner->handle = handle;
+ page_owner->order = order;
+ page_owner->gfp_mask = gfp_mask;
+ page_owner->last_migrate_reason = -1;
+ page_owner->pid = current->pid;
+ page_owner->tgid = current->tgid;
+ page_owner->ts_nsec = local_clock();
+ strscpy(page_owner->comm, current->comm,
+ sizeof(page_owner->comm));
+ __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
+ __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
+
+ page_ext = page_ext_next(page_ext);
+ }
+}
+
+noinline void __set_page_owner(struct page *page, unsigned short order,
+ gfp_t gfp_mask)
+{
+ struct page_ext *page_ext;
+ depot_stack_handle_t handle;
+
+ handle = save_stack(gfp_mask);
+
+ page_ext = page_ext_get(page);
+ if (unlikely(!page_ext))
+ return;
+ __set_page_owner_handle(page_ext, handle, order, gfp_mask);
+ page_ext_put(page_ext);
+}
+
+void __set_page_owner_migrate_reason(struct page *page, int reason)
+{
+ struct page_ext *page_ext = page_ext_get(page);
+ struct page_owner *page_owner;
+
+ if (unlikely(!page_ext))
+ return;
+
+ page_owner = get_page_owner(page_ext);
+ page_owner->last_migrate_reason = reason;
+ page_ext_put(page_ext);
+}
+
+void __split_page_owner(struct page *page, unsigned int nr)
+{
+ int i;
+ struct page_ext *page_ext = page_ext_get(page);
+ struct page_owner *page_owner;
+
+ if (unlikely(!page_ext))
+ return;
+
+ for (i = 0; i < nr; i++) {
+ page_owner = get_page_owner(page_ext);
+ page_owner->order = 0;
+ page_ext = page_ext_next(page_ext);
+ }
+ page_ext_put(page_ext);
+}
+
+void __folio_copy_owner(struct folio *newfolio, struct folio *old)
+{
+ struct page_ext *old_ext;
+ struct page_ext *new_ext;
+ struct page_owner *old_page_owner, *new_page_owner;
+
+ old_ext = page_ext_get(&old->page);
+ if (unlikely(!old_ext))
+ return;
+
+ new_ext = page_ext_get(&newfolio->page);
+ if (unlikely(!new_ext)) {
+ page_ext_put(old_ext);
+ return;
+ }
+
+ old_page_owner = get_page_owner(old_ext);
+ new_page_owner = get_page_owner(new_ext);
+ new_page_owner->order = old_page_owner->order;
+ new_page_owner->gfp_mask = old_page_owner->gfp_mask;
+ new_page_owner->last_migrate_reason =
+ old_page_owner->last_migrate_reason;
+ new_page_owner->handle = old_page_owner->handle;
+ new_page_owner->pid = old_page_owner->pid;
+ new_page_owner->tgid = old_page_owner->tgid;
+ new_page_owner->ts_nsec = old_page_owner->ts_nsec;
+ new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
+ strcpy(new_page_owner->comm, old_page_owner->comm);
+
+ /*
+ * We don't clear the bit on the old folio as it's going to be freed
+ * after migration. Until then, the info can be useful in case of
+ * a bug, and the overall stats will be off a bit only temporarily.
+ * Also, migrate_misplaced_transhuge_page() can still fail the
+ * migration and then we want the old folio to retain the info. But
+ * in that case we also don't need to explicitly clear the info from
+ * the new page, which will be freed.
+ */
+ __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
+ __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
+ page_ext_put(new_ext);
+ page_ext_put(old_ext);
+}
+
+void pagetypeinfo_showmixedcount_print(struct seq_file *m,
+ pg_data_t *pgdat, struct zone *zone)
+{
+ struct page *page;
+ struct page_ext *page_ext;
+ struct page_owner *page_owner;
+ unsigned long pfn, block_end_pfn;
+ unsigned long end_pfn = zone_end_pfn(zone);
+ unsigned long count[MIGRATE_TYPES] = { 0, };
+ int pageblock_mt, page_mt;
+ int i;
+
+ /* Scan block by block. First and last block may be incomplete */
+ pfn = zone->zone_start_pfn;
+
+ /*
+ * Walk the zone in pageblock_nr_pages steps. If a page block spans
+ * a zone boundary, it will be double counted between zones. This does
+ * not matter as the mixed block count will still be correct
+ */
+ for (; pfn < end_pfn; ) {
+ page = pfn_to_online_page(pfn);
+ if (!page) {
+ pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
+ continue;
+ }
+
+ block_end_pfn = pageblock_end_pfn(pfn);
+ block_end_pfn = min(block_end_pfn, end_pfn);
+
+ pageblock_mt = get_pageblock_migratetype(page);
+
+ for (; pfn < block_end_pfn; pfn++) {
+ /* The pageblock is online, no need to recheck. */
+ page = pfn_to_page(pfn);
+
+ if (page_zone(page) != zone)
+ continue;
+
+ if (PageBuddy(page)) {
+ unsigned long freepage_order;
+
+ freepage_order = buddy_order_unsafe(page);
+ if (freepage_order < MAX_ORDER)
+ pfn += (1UL << freepage_order) - 1;
+ continue;
+ }
+
+ if (PageReserved(page))
+ continue;
+
+ page_ext = page_ext_get(page);
+ if (unlikely(!page_ext))
+ continue;
+
+ if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
+ goto ext_put_continue;
+
+ page_owner = get_page_owner(page_ext);
+ page_mt = gfp_migratetype(page_owner->gfp_mask);
+ if (pageblock_mt != page_mt) {
+ if (is_migrate_cma(pageblock_mt))
+ count[MIGRATE_MOVABLE]++;
+ else
+ count[pageblock_mt]++;
+
+ pfn = block_end_pfn;
+ page_ext_put(page_ext);
+ break;
+ }
+ pfn += (1UL << page_owner->order) - 1;
+ext_put_continue:
+ page_ext_put(page_ext);
+ }
+ }
+
+ /* Print counts */
+ seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
+ for (i = 0; i < MIGRATE_TYPES; i++)
+ seq_printf(m, "%12lu ", count[i]);
+ seq_putc(m, '\n');
+}
+
+/*
+ * Looking for memcg information and print it out
+ */
+static inline int print_page_owner_memcg(char *kbuf, size_t count, int ret,
+ struct page *page)
+{
+#ifdef CONFIG_MEMCG
+ unsigned long memcg_data;
+ struct mem_cgroup *memcg;
+ bool online;
+ char name[80];
+
+ rcu_read_lock();
+ memcg_data = READ_ONCE(page->memcg_data);
+ if (!memcg_data)
+ goto out_unlock;
+
+ if (memcg_data & MEMCG_DATA_OBJCGS)
+ ret += scnprintf(kbuf + ret, count - ret,
+ "Slab cache page\n");
+
+ memcg = page_memcg_check(page);
+ if (!memcg)
+ goto out_unlock;
+
+ online = (memcg->css.flags & CSS_ONLINE);
+ cgroup_name(memcg->css.cgroup, name, sizeof(name));
+ ret += scnprintf(kbuf + ret, count - ret,
+ "Charged %sto %smemcg %s\n",
+ PageMemcgKmem(page) ? "(via objcg) " : "",
+ online ? "" : "offline ",
+ name);
+out_unlock:
+ rcu_read_unlock();
+#endif /* CONFIG_MEMCG */
+
+ return ret;
+}
+
+static ssize_t
+print_page_owner(char __user *buf, size_t count, unsigned long pfn,
+ struct page *page, struct page_owner *page_owner,
+ depot_stack_handle_t handle)
+{
+ int ret, pageblock_mt, page_mt;
+ char *kbuf;
+
+ count = min_t(size_t, count, PAGE_SIZE);
+ kbuf = kmalloc(count, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ ret = scnprintf(kbuf, count,
+ "Page allocated via order %u, mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu ns, free_ts %llu ns\n",
+ page_owner->order, page_owner->gfp_mask,
+ &page_owner->gfp_mask, page_owner->pid,
+ page_owner->tgid, page_owner->comm,
+ page_owner->ts_nsec, page_owner->free_ts_nsec);
+
+ /* Print information relevant to grouping pages by mobility */
+ pageblock_mt = get_pageblock_migratetype(page);
+ page_mt = gfp_migratetype(page_owner->gfp_mask);
+ ret += scnprintf(kbuf + ret, count - ret,
+ "PFN %lu type %s Block %lu type %s Flags %pGp\n",
+ pfn,
+ migratetype_names[page_mt],
+ pfn >> pageblock_order,
+ migratetype_names[pageblock_mt],
+ &page->flags);
+
+ ret += stack_depot_snprint(handle, kbuf + ret, count - ret, 0);
+ if (ret >= count)
+ goto err;
+
+ if (page_owner->last_migrate_reason != -1) {
+ ret += scnprintf(kbuf + ret, count - ret,
+ "Page has been migrated, last migrate reason: %s\n",
+ migrate_reason_names[page_owner->last_migrate_reason]);
+ }
+
+ ret = print_page_owner_memcg(kbuf, count, ret, page);
+
+ ret += snprintf(kbuf + ret, count - ret, "\n");
+ if (ret >= count)
+ goto err;
+
+ if (copy_to_user(buf, kbuf, ret))
+ ret = -EFAULT;
+
+ kfree(kbuf);
+ return ret;
+
+err:
+ kfree(kbuf);
+ return -ENOMEM;
+}
+
+void __dump_page_owner(const struct page *page)
+{
+ struct page_ext *page_ext = page_ext_get((void *)page);
+ struct page_owner *page_owner;
+ depot_stack_handle_t handle;
+ gfp_t gfp_mask;
+ int mt;
+
+ if (unlikely(!page_ext)) {
+ pr_alert("There is not page extension available.\n");
+ return;
+ }
+
+ page_owner = get_page_owner(page_ext);
+ gfp_mask = page_owner->gfp_mask;
+ mt = gfp_migratetype(gfp_mask);
+
+ if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
+ pr_alert("page_owner info is not present (never set?)\n");
+ page_ext_put(page_ext);
+ return;
+ }
+
+ if (test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
+ pr_alert("page_owner tracks the page as allocated\n");
+ else
+ pr_alert("page_owner tracks the page as freed\n");
+
+ pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, tgid %d (%s), ts %llu, free_ts %llu\n",
+ page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
+ page_owner->pid, page_owner->tgid, page_owner->comm,
+ page_owner->ts_nsec, page_owner->free_ts_nsec);
+
+ handle = READ_ONCE(page_owner->handle);
+ if (!handle)
+ pr_alert("page_owner allocation stack trace missing\n");
+ else
+ stack_depot_print(handle);
+
+ handle = READ_ONCE(page_owner->free_handle);
+ if (!handle) {
+ pr_alert("page_owner free stack trace missing\n");
+ } else {
+ pr_alert("page last free stack trace:\n");
+ stack_depot_print(handle);
+ }
+
+ if (page_owner->last_migrate_reason != -1)
+ pr_alert("page has been migrated, last migrate reason: %s\n",
+ migrate_reason_names[page_owner->last_migrate_reason]);
+ page_ext_put(page_ext);
+}
+
+static ssize_t
+read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+ unsigned long pfn;
+ struct page *page;
+ struct page_ext *page_ext;
+ struct page_owner *page_owner;
+ depot_stack_handle_t handle;
+
+ if (!static_branch_unlikely(&page_owner_inited))
+ return -EINVAL;
+
+ page = NULL;
+ if (*ppos == 0)
+ pfn = min_low_pfn;
+ else
+ pfn = *ppos;
+ /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
+ while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
+ pfn++;
+
+ /* Find an allocated page */
+ for (; pfn < max_pfn; pfn++) {
+ /*
+ * This temporary page_owner is required so
+ * that we can avoid the context switches while holding
+ * the rcu lock and copying the page owner information to
+ * user through copy_to_user() or GFP_KERNEL allocations.
+ */
+ struct page_owner page_owner_tmp;
+
+ /*
+ * If the new page is in a new MAX_ORDER_NR_PAGES area,
+ * validate the area as existing, skip it if not
+ */
+ if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
+ pfn += MAX_ORDER_NR_PAGES - 1;
+ continue;
+ }
+
+ page = pfn_to_page(pfn);
+ if (PageBuddy(page)) {
+ unsigned long freepage_order = buddy_order_unsafe(page);
+
+ if (freepage_order < MAX_ORDER)
+ pfn += (1UL << freepage_order) - 1;
+ continue;
+ }
+
+ page_ext = page_ext_get(page);
+ if (unlikely(!page_ext))
+ continue;
+
+ /*
+ * Some pages could be missed by concurrent allocation or free,
+ * because we don't hold the zone lock.
+ */
+ if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+ goto ext_put_continue;
+
+ /*
+ * Although we do have the info about past allocation of free
+ * pages, it's not relevant for current memory usage.
+ */
+ if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
+ goto ext_put_continue;
+
+ page_owner = get_page_owner(page_ext);
+
+ /*
+ * Don't print "tail" pages of high-order allocations as that
+ * would inflate the stats.
+ */
+ if (!IS_ALIGNED(pfn, 1 << page_owner->order))
+ goto ext_put_continue;
+
+ /*
+ * Access to page_ext->handle isn't synchronous so we should
+ * be careful to access it.
+ */
+ handle = READ_ONCE(page_owner->handle);
+ if (!handle)
+ goto ext_put_continue;
+
+ /* Record the next PFN to read in the file offset */
+ *ppos = pfn + 1;
+
+ page_owner_tmp = *page_owner;
+ page_ext_put(page_ext);
+ return print_page_owner(buf, count, pfn, page,
+ &page_owner_tmp, handle);
+ext_put_continue:
+ page_ext_put(page_ext);
+ }
+
+ return 0;
+}
+
+static loff_t lseek_page_owner(struct file *file, loff_t offset, int orig)
+{
+ switch (orig) {
+ case SEEK_SET:
+ file->f_pos = offset;
+ break;
+ case SEEK_CUR:
+ file->f_pos += offset;
+ break;
+ default:
+ return -EINVAL;
+ }
+ return file->f_pos;
+}
+
+static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
+{
+ unsigned long pfn = zone->zone_start_pfn;
+ unsigned long end_pfn = zone_end_pfn(zone);
+ unsigned long count = 0;
+
+ /*
+ * Walk the zone in pageblock_nr_pages steps. If a page block spans
+ * a zone boundary, it will be double counted between zones. This does
+ * not matter as the mixed block count will still be correct
+ */
+ for (; pfn < end_pfn; ) {
+ unsigned long block_end_pfn;
+
+ if (!pfn_valid(pfn)) {
+ pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
+ continue;
+ }
+
+ block_end_pfn = pageblock_end_pfn(pfn);
+ block_end_pfn = min(block_end_pfn, end_pfn);
+
+ for (; pfn < block_end_pfn; pfn++) {
+ struct page *page = pfn_to_page(pfn);
+ struct page_ext *page_ext;
+
+ if (page_zone(page) != zone)
+ continue;
+
+ /*
+ * To avoid having to grab zone->lock, be a little
+ * careful when reading buddy page order. The only
+ * danger is that we skip too much and potentially miss
+ * some early allocated pages, which is better than
+ * heavy lock contention.
+ */
+ if (PageBuddy(page)) {
+ unsigned long order = buddy_order_unsafe(page);
+
+ if (order > 0 && order < MAX_ORDER)
+ pfn += (1UL << order) - 1;
+ continue;
+ }
+
+ if (PageReserved(page))
+ continue;
+
+ page_ext = page_ext_get(page);
+ if (unlikely(!page_ext))
+ continue;
+
+ /* Maybe overlapping zone */
+ if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
+ goto ext_put_continue;
+
+ /* Found early allocated page */
+ __set_page_owner_handle(page_ext, early_handle,
+ 0, 0);
+ count++;
+ext_put_continue:
+ page_ext_put(page_ext);
+ }
+ cond_resched();
+ }
+
+ pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
+ pgdat->node_id, zone->name, count);
+}
+
+static void init_zones_in_node(pg_data_t *pgdat)
+{
+ struct zone *zone;
+ struct zone *node_zones = pgdat->node_zones;
+
+ for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
+ if (!populated_zone(zone))
+ continue;
+
+ init_pages_in_zone(pgdat, zone);
+ }
+}
+
+static void init_early_allocated_pages(void)
+{
+ pg_data_t *pgdat;
+
+ for_each_online_pgdat(pgdat)
+ init_zones_in_node(pgdat);
+}
+
+static const struct file_operations proc_page_owner_operations = {
+ .read = read_page_owner,
+ .llseek = lseek_page_owner,
+};
+
+static int __init pageowner_init(void)
+{
+ if (!static_branch_unlikely(&page_owner_inited)) {
+ pr_info("page_owner is disabled\n");
+ return 0;
+ }
+
+ debugfs_create_file("page_owner", 0400, NULL, NULL,
+ &proc_page_owner_operations);
+
+ return 0;
+}
+late_initcall(pageowner_init)