diff options
Diffstat (limited to '')
| -rw-r--r-- | mm/page_owner.c | 726 |
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) |