// 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; pid_t free_pid; pid_t free_tgid; }; struct stack { struct stack_record *stack_record; struct stack *next; }; static struct stack dummy_stack; static struct stack failure_stack; static struct stack *stack_list; static DEFINE_SPINLOCK(stack_list_lock); 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 inline void set_current_in_page_owner(void) { /* * Avoid recursion. * * We might need to allocate more memory from page_owner code, so make * sure to signal it in order to avoid recursion. */ current->in_page_owner = 1; } static inline void unset_current_in_page_owner(void) { current->in_page_owner = 0; } static int __init early_page_owner_param(char *buf) { int ret = kstrtobool(buf, &page_owner_enabled); if (page_owner_enabled) stack_depot_request_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(); init_early_allocated_pages(); /* Initialize dummy and failure stacks and link them to stack_list */ dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle); if (dummy_stack.stack_record) refcount_set(&dummy_stack.stack_record->count, 1); if (failure_stack.stack_record) refcount_set(&failure_stack.stack_record->count, 1); dummy_stack.next = &failure_stack; stack_list = &dummy_stack; static_branch_enable(&page_owner_inited); } struct page_ext_operations page_owner_ops = { .size = sizeof(struct page_owner), .need = need_page_owner, .init = init_page_owner, .need_shared_flags = true, }; static inline struct page_owner *get_page_owner(struct page_ext *page_ext) { return page_ext_data(page_ext, &page_owner_ops); } 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; if (current->in_page_owner) return dummy_handle; set_current_in_page_owner(); nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2); handle = stack_depot_save(entries, nr_entries, flags); if (!handle) handle = failure_handle; unset_current_in_page_owner(); return handle; } static void add_stack_record_to_list(struct stack_record *stack_record, gfp_t gfp_mask) { unsigned long flags; struct stack *stack; /* Filter gfp_mask the same way stackdepot does, for consistency */ gfp_mask &= ~GFP_ZONEMASK; gfp_mask &= (GFP_ATOMIC | GFP_KERNEL | __GFP_NOLOCKDEP); gfp_mask |= __GFP_NOWARN; set_current_in_page_owner(); stack = kmalloc(sizeof(*stack), gfp_mask); if (!stack) { unset_current_in_page_owner(); return; } unset_current_in_page_owner(); stack->stack_record = stack_record; stack->next = NULL; spin_lock_irqsave(&stack_list_lock, flags); stack->next = stack_list; /* * This pairs with smp_load_acquire() from function * stack_start(). This guarantees that stack_start() * will see an updated stack_list before starting to * traverse the list. */ smp_store_release(&stack_list, stack); spin_unlock_irqrestore(&stack_list_lock, flags); } static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_mask, int nr_base_pages) { struct stack_record *stack_record = __stack_depot_get_stack_record(handle); if (!stack_record) return; /* * New stack_record's that do not use STACK_DEPOT_FLAG_GET start * with REFCOUNT_SATURATED to catch spurious increments of their * refcount. * Since we do not use STACK_DEPOT_FLAG_GET API, let us * set a refcount of 1 ourselves. */ if (refcount_read(&stack_record->count) == REFCOUNT_SATURATED) { int old = REFCOUNT_SATURATED; if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1)) /* Add the new stack_record to our list */ add_stack_record_to_list(stack_record, gfp_mask); } refcount_add(nr_base_pages, &stack_record->count); } static void dec_stack_record_count(depot_stack_handle_t handle, int nr_base_pages) { struct stack_record *stack_record = __stack_depot_get_stack_record(handle); if (!stack_record) return; if (refcount_sub_and_test(nr_base_pages, &stack_record->count)) pr_warn("%s: refcount went to 0 for %u handle\n", __func__, handle); } static inline void __update_page_owner_handle(struct page_ext *page_ext, depot_stack_handle_t handle, unsigned short order, gfp_t gfp_mask, short last_migrate_reason, u64 ts_nsec, pid_t pid, pid_t tgid, char *comm) { int i; struct page_owner *page_owner; 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 = last_migrate_reason; page_owner->pid = pid; page_owner->tgid = tgid; page_owner->ts_nsec = ts_nsec; strscpy(page_owner->comm, 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); } } static inline void __update_page_owner_free_handle(struct page_ext *page_ext, depot_stack_handle_t handle, unsigned short order, pid_t pid, pid_t tgid, u64 free_ts_nsec) { int i; struct page_owner *page_owner; for (i = 0; i < (1 << order); i++) { page_owner = get_page_owner(page_ext); /* Only __reset_page_owner() wants to clear the bit */ if (handle) { __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); page_owner->free_handle = handle; } page_owner->free_ts_nsec = free_ts_nsec; page_owner->free_pid = current->pid; page_owner->free_tgid = current->tgid; page_ext = page_ext_next(page_ext); } } void __reset_page_owner(struct page *page, unsigned short order) { struct page_ext *page_ext; depot_stack_handle_t handle; depot_stack_handle_t alloc_handle; struct page_owner *page_owner; u64 free_ts_nsec = local_clock(); page_ext = page_ext_get(page); if (unlikely(!page_ext)) return; page_owner = get_page_owner(page_ext); alloc_handle = page_owner->handle; handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); __update_page_owner_free_handle(page_ext, handle, order, current->pid, current->tgid, free_ts_nsec); page_ext_put(page_ext); if (alloc_handle != early_handle) /* * early_handle is being set as a handle for all those * early allocated pages. See init_pages_in_zone(). * Since their refcount is not being incremented because * the machinery is not ready yet, we cannot decrement * their refcount either. */ dec_stack_record_count(alloc_handle, 1 << order); } noinline void __set_page_owner(struct page *page, unsigned short order, gfp_t gfp_mask) { struct page_ext *page_ext; u64 ts_nsec = local_clock(); depot_stack_handle_t handle; handle = save_stack(gfp_mask); page_ext = page_ext_get(page); if (unlikely(!page_ext)) return; __update_page_owner_handle(page_ext, handle, order, gfp_mask, -1, ts_nsec, current->pid, current->tgid, current->comm); page_ext_put(page_ext); inc_stack_record_count(handle, gfp_mask, 1 << order); } 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, int old_order, int new_order) { 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 < (1 << old_order); i++) { page_owner = get_page_owner(page_ext); page_owner->order = new_order; page_ext = page_ext_next(page_ext); } page_ext_put(page_ext); } void __folio_copy_owner(struct folio *newfolio, struct folio *old) { int i; struct page_ext *old_ext; struct page_ext *new_ext; struct page_owner *old_page_owner; struct page_owner *new_page_owner; depot_stack_handle_t migrate_handle; 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); migrate_handle = new_page_owner->handle; __update_page_owner_handle(new_ext, old_page_owner->handle, old_page_owner->order, old_page_owner->gfp_mask, old_page_owner->last_migrate_reason, old_page_owner->ts_nsec, old_page_owner->pid, old_page_owner->tgid, old_page_owner->comm); /* * Do not proactively clear PAGE_EXT_OWNER{_ALLOCATED} bits as the folio * will be freed after migration. Keep them until then as they may be * useful. */ __update_page_owner_free_handle(new_ext, 0, old_page_owner->order, old_page_owner->free_pid, old_page_owner->free_tgid, old_page_owner->free_ts_nsec); /* * We linked the original stack to the new folio, we need to do the same * for the new one and the old folio otherwise there will be an imbalance * when subtracting those pages from the stack. */ for (i = 0; i < (1 << new_page_owner->order); i++) { old_page_owner->handle = migrate_handle; old_ext = page_ext_next(old_ext); old_page_owner = get_page_owner(old_ext); } 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_PAGE_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\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); /* 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 0x%lx 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 pid %d tgid %d stack trace:\n", page_owner->free_pid, page_owner->free_tgid); 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_PAGE_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_PAGE_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 */ __update_page_owner_handle(page_ext, early_handle, 0, 0, -1, local_clock(), current->pid, current->tgid, current->comm); 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 void *stack_start(struct seq_file *m, loff_t *ppos) { struct stack *stack; if (*ppos == -1UL) return NULL; if (!*ppos) { /* * This pairs with smp_store_release() from function * add_stack_record_to_list(), so we get a consistent * value of stack_list. */ stack = smp_load_acquire(&stack_list); m->private = stack; } else { stack = m->private; } return stack; } static void *stack_next(struct seq_file *m, void *v, loff_t *ppos) { struct stack *stack = v; stack = stack->next; *ppos = stack ? *ppos + 1 : -1UL; m->private = stack; return stack; } static unsigned long page_owner_pages_threshold; static int stack_print(struct seq_file *m, void *v) { int i, nr_base_pages; struct stack *stack = v; unsigned long *entries; unsigned long nr_entries; struct stack_record *stack_record = stack->stack_record; if (!stack->stack_record) return 0; nr_entries = stack_record->size; entries = stack_record->entries; nr_base_pages = refcount_read(&stack_record->count) - 1; if (nr_base_pages < 1 || nr_base_pages < page_owner_pages_threshold) return 0; for (i = 0; i < nr_entries; i++) seq_printf(m, " %pS\n", (void *)entries[i]); seq_printf(m, "nr_base_pages: %d\n\n", nr_base_pages); return 0; } static void stack_stop(struct seq_file *m, void *v) { } static const struct seq_operations page_owner_stack_op = { .start = stack_start, .next = stack_next, .stop = stack_stop, .show = stack_print }; static int page_owner_stack_open(struct inode *inode, struct file *file) { return seq_open_private(file, &page_owner_stack_op, 0); } static const struct file_operations page_owner_stack_operations = { .open = page_owner_stack_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release, }; static int page_owner_threshold_get(void *data, u64 *val) { *val = READ_ONCE(page_owner_pages_threshold); return 0; } static int page_owner_threshold_set(void *data, u64 val) { WRITE_ONCE(page_owner_pages_threshold, val); return 0; } DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get, &page_owner_threshold_set, "%llu"); static int __init pageowner_init(void) { struct dentry *dir; 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); dir = debugfs_create_dir("page_owner_stacks", NULL); debugfs_create_file("show_stacks", 0400, dir, NULL, &page_owner_stack_operations); debugfs_create_file("count_threshold", 0600, dir, NULL, &proc_page_owner_threshold); return 0; } late_initcall(pageowner_init)