blob: 25d2405407b97692f361240ca790028c313c174c [file] [log] [blame]
// 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/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;
pid_t pid;
};
static bool page_owner_enabled = false;
DEFINE_STATIC_KEY_FALSE(page_owner_inited);
EXPORT_SYMBOL_GPL(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)
{
return kstrtobool(buf, &page_owner_enabled);
}
early_param("page_owner", early_page_owner_param);
static 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 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;
}
depot_stack_handle_t get_page_owner_handle(struct page_ext *page_ext, unsigned long pfn)
{
struct page_owner *page_owner;
depot_stack_handle_t handle;
if (!page_owner_enabled)
return 0;
page_owner = get_page_owner(page_ext);
/* skip handle for tail pages of higher order allocations */
if (!IS_ALIGNED(pfn, 1 << page_owner->order))
return 0;
handle = READ_ONCE(page_owner->handle);
return handle;
}
EXPORT_SYMBOL_NS_GPL(get_page_owner_handle, MINIDUMP);
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 int order)
{
int i;
struct page_ext *page_ext;
depot_stack_handle_t handle;
struct page_owner *page_owner;
u64 free_ts_nsec = local_clock();
handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
return;
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 int 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->ts_nsec = local_clock();
__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 int 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);
}
EXPORT_SYMBOL_GPL(__set_page_owner);
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 __copy_page_owner(struct page *oldpage, struct page *newpage)
{
struct page_ext *old_ext;
struct page_ext *new_ext;
struct page_owner *old_page_owner, *new_page_owner;
old_ext = page_ext_get(oldpage);
if (unlikely(!old_ext))
return;
new_ext = page_ext_get(newpage);
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->ts_nsec = old_page_owner->ts_nsec;
new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
/*
* We don't clear the bit on the oldpage 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 oldpage 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 = ALIGN(pfn + 1, pageblock_nr_pages);
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');
}
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;
unsigned long *entries;
unsigned int nr_entries;
char *kbuf;
count = min_t(size_t, count, PAGE_SIZE);
kbuf = kmalloc(count, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
ret = snprintf(kbuf, count,
"Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n",
page_owner->order, page_owner->gfp_mask,
&page_owner->gfp_mask, page_owner->pid,
page_owner->ts_nsec, page_owner->free_ts_nsec);
if (ret >= count)
goto err;
/* Print information relevant to grouping pages by mobility */
pageblock_mt = get_pageblock_migratetype(page);
page_mt = gfp_migratetype(page_owner->gfp_mask);
ret += snprintf(kbuf + ret, count - ret,
"PFN %lu type %s Block %lu type %s Flags %#lx(%pGp)\n",
pfn,
migratetype_names[page_mt],
pfn >> pageblock_order,
migratetype_names[pageblock_mt],
page->flags, &page->flags);
if (ret >= count)
goto err;
nr_entries = stack_depot_fetch(handle, &entries);
ret += stack_trace_snprint(kbuf + ret, count - ret, entries, nr_entries, 0);
if (ret >= count)
goto err;
if (page_owner->last_migrate_reason != -1) {
ret += snprintf(kbuf + ret, count - ret,
"Page has been migrated, last migrate reason: %s\n",
migrate_reason_names[page_owner->last_migrate_reason]);
if (ret >= count)
goto err;
}
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;
unsigned long *entries;
unsigned int nr_entries;
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, ts %llu, free_ts %llu\n",
page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
page_owner->pid, 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 {
nr_entries = stack_depot_fetch(handle, &entries);
stack_trace_print(entries, nr_entries, 0);
}
handle = READ_ONCE(page_owner->free_handle);
if (!handle) {
pr_alert("page_owner free stack trace missing\n");
} else {
nr_entries = stack_depot_fetch(handle, &entries);
pr_alert("page last free stack trace:\n");
stack_trace_print(entries, nr_entries, 0);
}
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;
pfn = min_low_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++;
drain_all_pages(NULL);
/* 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 - min_low_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 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 = ALIGN(pfn + 1, pageblock_nr_pages);
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,
};
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)