// 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_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(); 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, .need_shared_flags = true, }; 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; u64 ts_nsec = local_clock(); 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 = ts_nsec; 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 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 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)