linux/mm/page_owner.c
Liam Mark 9cc7e96aa8 mm/page_owner: record timestamp and pid
Collect the time for each allocation recorded in page owner so that
allocation "surges" can be measured.

Record the pid for each allocation recorded in page owner so that the
source of allocation "surges" can be better identified.

The above is very useful when doing memory analysis.  On a crash for
example, we can get this information from kdump (or ramdump) and parse it
to figure out memory allocation problems.

Please note that on x86_64 this increases the size of struct page_owner
from 16 bytes to 32.

Vlastimil: it's not a functionality intended for production, so unless
somebody says they need to enable page_owner for debugging and this
increase prevents them from fitting into available memory, let's not
complicate things with making this optional.

[lmark@codeaurora.org: v3]
  Link: https://lkml.kernel.org/r/20201210160357.27779-1-georgi.djakov@linaro.org

Link: https://lkml.kernel.org/r/20201209125153.10533-1-georgi.djakov@linaro.org
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-12-15 12:13:38 -08:00

664 lines
16 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/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;
pid_t pid;
};
static bool page_owner_enabled = false;
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)
{
if (!buf)
return -EINVAL;
if (strcmp(buf, "on") == 0)
page_owner_enabled = true;
return 0;
}
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;
}
static inline bool check_recursive_alloc(unsigned long *entries,
unsigned int nr_entries,
unsigned long ip)
{
unsigned int i;
for (i = 0; i < nr_entries; i++) {
if (entries[i] == ip)
return true;
}
return false;
}
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;
nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
/*
* We need to check recursion here because our request to
* stackdepot could trigger memory allocation to save new
* entry. New memory allocation would reach here and call
* stack_depot_save_entries() again if we don't catch it. There is
* still not enough memory in stackdepot so it would try to
* allocate memory again and loop forever.
*/
if (check_recursive_alloc(entries, nr_entries, _RET_IP_))
return dummy_handle;
handle = stack_depot_save(entries, nr_entries, flags);
if (!handle)
handle = failure_handle;
return handle;
}
void __reset_page_owner(struct page *page, unsigned int order)
{
int i;
struct page_ext *page_ext;
depot_stack_handle_t handle = 0;
struct page_owner *page_owner;
handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
page_ext = lookup_page_ext(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_ext = page_ext_next(page_ext);
}
}
static inline void __set_page_owner_handle(struct page *page,
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 = lookup_page_ext(page);
depot_stack_handle_t handle;
if (unlikely(!page_ext))
return;
handle = save_stack(gfp_mask);
__set_page_owner_handle(page, page_ext, handle, order, gfp_mask);
}
void __set_page_owner_migrate_reason(struct page *page, int reason)
{
struct page_ext *page_ext = lookup_page_ext(page);
struct page_owner *page_owner;
if (unlikely(!page_ext))
return;
page_owner = get_page_owner(page_ext);
page_owner->last_migrate_reason = reason;
}
void __split_page_owner(struct page *page, unsigned int nr)
{
int i;
struct page_ext *page_ext = lookup_page_ext(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);
}
}
void __copy_page_owner(struct page *oldpage, struct page *newpage)
{
struct page_ext *old_ext = lookup_page_ext(oldpage);
struct page_ext *new_ext = lookup_page_ext(newpage);
struct page_owner *old_page_owner, *new_page_owner;
if (unlikely(!old_ext || !new_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;
/*
* 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 overal 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);
}
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 = zone->zone_start_pfn, block_end_pfn;
unsigned long end_pfn = pfn + zone->spanned_pages;
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++) {
if (!pfn_valid_within(pfn))
continue;
/* 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 = lookup_page_ext(page);
if (unlikely(!page_ext))
continue;
if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags))
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;
break;
}
pfn += (1UL << page_owner->order) - 1;
}
}
/* 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\n",
page_owner->order, page_owner->gfp_mask,
&page_owner->gfp_mask, page_owner->pid,
page_owner->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(struct page *page)
{
struct page_ext *page_ext = lookup_page_ext(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");
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\n",
page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask,
page_owner->pid, page_owner->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]);
}
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++) {
/*
* 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;
}
/* Check for holes within a MAX_ORDER area */
if (!pfn_valid_within(pfn))
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 = lookup_page_ext(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))
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))
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))
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)
continue;
/* Record the next PFN to read in the file offset */
*ppos = (pfn - min_low_pfn) + 1;
return print_page_owner(buf, count, pfn, page,
page_owner, handle);
}
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;
struct page_ext *page_ext;
if (!pfn_valid_within(pfn))
continue;
page = pfn_to_page(pfn);
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 = lookup_page_ext(page);
if (unlikely(!page_ext))
continue;
/* Maybe overlapping zone */
if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
continue;
/* Found early allocated page */
__set_page_owner_handle(page, page_ext, early_handle,
0, 0);
count++;
}
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)