linux/mm/page_owner.c
Hyeonggon Yoo 05a4219955 mm/page_owner: record single timestamp value for high order allocations
When allocating a high-order page, separate allocation timestamp is
recorded for each sub-page resulting in different timestamp values between
them.

This behavior is not consistent with the behavior when recording free
timestamp and caused confusion when analyzing memory dumps.  Record single
timestamp for the entire allocation, aligning with the behavior for free
timestamps.

Link: https://lkml.kernel.org/r/20230121165054.520507-1-42.hyeyoo@gmail.com
Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02 22:33:28 -08:00

729 lines
18 KiB
C

// 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,
.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 %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)