linux-hardened/mm/list_lru.c
Roman Gushchin 4d96ba3530 mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages
Every slab page charged to a non-root memory cgroup has a pointer to the
memory cgroup and holds a reference to it, which protects a non-empty
memory cgroup from being released.  At the same time the page has a
pointer to the corresponding kmem_cache, and also hold a reference to the
kmem_cache.  And kmem_cache by itself holds a reference to the cgroup.

So there is clearly some redundancy, which allows to stop setting the
page->mem_cgroup pointer and rely on getting memcg pointer indirectly via
kmem_cache.  Further it will allow to change this pointer easier, without
a need to go over all charged pages.

So let's stop setting page->mem_cgroup pointer for slab pages, and stop
using the css refcounter directly for protecting the memory cgroup from
going away.  Instead rely on kmem_cache as an intermediate object.

Make sure that vmstats and shrinker lists are working as previously, as
well as /proc/kpagecgroup interface.

Link: http://lkml.kernel.org/r/20190611231813.3148843-10-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-12 11:05:44 -07:00

659 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
* Authors: David Chinner and Glauber Costa
*
* Generic LRU infrastructure
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/list_lru.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/memcontrol.h>
#include "slab.h"
#ifdef CONFIG_MEMCG_KMEM
static LIST_HEAD(list_lrus);
static DEFINE_MUTEX(list_lrus_mutex);
static void list_lru_register(struct list_lru *lru)
{
mutex_lock(&list_lrus_mutex);
list_add(&lru->list, &list_lrus);
mutex_unlock(&list_lrus_mutex);
}
static void list_lru_unregister(struct list_lru *lru)
{
mutex_lock(&list_lrus_mutex);
list_del(&lru->list);
mutex_unlock(&list_lrus_mutex);
}
static int lru_shrinker_id(struct list_lru *lru)
{
return lru->shrinker_id;
}
static inline bool list_lru_memcg_aware(struct list_lru *lru)
{
return lru->memcg_aware;
}
static inline struct list_lru_one *
list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
{
struct list_lru_memcg *memcg_lrus;
/*
* Either lock or RCU protects the array of per cgroup lists
* from relocation (see memcg_update_list_lru_node).
*/
memcg_lrus = rcu_dereference_check(nlru->memcg_lrus,
lockdep_is_held(&nlru->lock));
if (memcg_lrus && idx >= 0)
return memcg_lrus->lru[idx];
return &nlru->lru;
}
static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
{
struct page *page;
if (!memcg_kmem_enabled())
return NULL;
page = virt_to_head_page(ptr);
return memcg_from_slab_page(page);
}
static inline struct list_lru_one *
list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
struct mem_cgroup **memcg_ptr)
{
struct list_lru_one *l = &nlru->lru;
struct mem_cgroup *memcg = NULL;
if (!nlru->memcg_lrus)
goto out;
memcg = mem_cgroup_from_kmem(ptr);
if (!memcg)
goto out;
l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
out:
if (memcg_ptr)
*memcg_ptr = memcg;
return l;
}
#else
static void list_lru_register(struct list_lru *lru)
{
}
static void list_lru_unregister(struct list_lru *lru)
{
}
static int lru_shrinker_id(struct list_lru *lru)
{
return -1;
}
static inline bool list_lru_memcg_aware(struct list_lru *lru)
{
return false;
}
static inline struct list_lru_one *
list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
{
return &nlru->lru;
}
static inline struct list_lru_one *
list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
struct mem_cgroup **memcg_ptr)
{
if (memcg_ptr)
*memcg_ptr = NULL;
return &nlru->lru;
}
#endif /* CONFIG_MEMCG_KMEM */
bool list_lru_add(struct list_lru *lru, struct list_head *item)
{
int nid = page_to_nid(virt_to_page(item));
struct list_lru_node *nlru = &lru->node[nid];
struct mem_cgroup *memcg;
struct list_lru_one *l;
spin_lock(&nlru->lock);
if (list_empty(item)) {
l = list_lru_from_kmem(nlru, item, &memcg);
list_add_tail(item, &l->list);
/* Set shrinker bit if the first element was added */
if (!l->nr_items++)
memcg_set_shrinker_bit(memcg, nid,
lru_shrinker_id(lru));
nlru->nr_items++;
spin_unlock(&nlru->lock);
return true;
}
spin_unlock(&nlru->lock);
return false;
}
EXPORT_SYMBOL_GPL(list_lru_add);
bool list_lru_del(struct list_lru *lru, struct list_head *item)
{
int nid = page_to_nid(virt_to_page(item));
struct list_lru_node *nlru = &lru->node[nid];
struct list_lru_one *l;
spin_lock(&nlru->lock);
if (!list_empty(item)) {
l = list_lru_from_kmem(nlru, item, NULL);
list_del_init(item);
l->nr_items--;
nlru->nr_items--;
spin_unlock(&nlru->lock);
return true;
}
spin_unlock(&nlru->lock);
return false;
}
EXPORT_SYMBOL_GPL(list_lru_del);
void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
{
list_del_init(item);
list->nr_items--;
}
EXPORT_SYMBOL_GPL(list_lru_isolate);
void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
struct list_head *head)
{
list_move(item, head);
list->nr_items--;
}
EXPORT_SYMBOL_GPL(list_lru_isolate_move);
unsigned long list_lru_count_one(struct list_lru *lru,
int nid, struct mem_cgroup *memcg)
{
struct list_lru_node *nlru = &lru->node[nid];
struct list_lru_one *l;
unsigned long count;
rcu_read_lock();
l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
count = l->nr_items;
rcu_read_unlock();
return count;
}
EXPORT_SYMBOL_GPL(list_lru_count_one);
unsigned long list_lru_count_node(struct list_lru *lru, int nid)
{
struct list_lru_node *nlru;
nlru = &lru->node[nid];
return nlru->nr_items;
}
EXPORT_SYMBOL_GPL(list_lru_count_node);
static unsigned long
__list_lru_walk_one(struct list_lru_node *nlru, int memcg_idx,
list_lru_walk_cb isolate, void *cb_arg,
unsigned long *nr_to_walk)
{
struct list_lru_one *l;
struct list_head *item, *n;
unsigned long isolated = 0;
l = list_lru_from_memcg_idx(nlru, memcg_idx);
restart:
list_for_each_safe(item, n, &l->list) {
enum lru_status ret;
/*
* decrement nr_to_walk first so that we don't livelock if we
* get stuck on large numbesr of LRU_RETRY items
*/
if (!*nr_to_walk)
break;
--*nr_to_walk;
ret = isolate(item, l, &nlru->lock, cb_arg);
switch (ret) {
case LRU_REMOVED_RETRY:
assert_spin_locked(&nlru->lock);
/* fall through */
case LRU_REMOVED:
isolated++;
nlru->nr_items--;
/*
* If the lru lock has been dropped, our list
* traversal is now invalid and so we have to
* restart from scratch.
*/
if (ret == LRU_REMOVED_RETRY)
goto restart;
break;
case LRU_ROTATE:
list_move_tail(item, &l->list);
break;
case LRU_SKIP:
break;
case LRU_RETRY:
/*
* The lru lock has been dropped, our list traversal is
* now invalid and so we have to restart from scratch.
*/
assert_spin_locked(&nlru->lock);
goto restart;
default:
BUG();
}
}
return isolated;
}
unsigned long
list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
list_lru_walk_cb isolate, void *cb_arg,
unsigned long *nr_to_walk)
{
struct list_lru_node *nlru = &lru->node[nid];
unsigned long ret;
spin_lock(&nlru->lock);
ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
nr_to_walk);
spin_unlock(&nlru->lock);
return ret;
}
EXPORT_SYMBOL_GPL(list_lru_walk_one);
unsigned long
list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
list_lru_walk_cb isolate, void *cb_arg,
unsigned long *nr_to_walk)
{
struct list_lru_node *nlru = &lru->node[nid];
unsigned long ret;
spin_lock_irq(&nlru->lock);
ret = __list_lru_walk_one(nlru, memcg_cache_id(memcg), isolate, cb_arg,
nr_to_walk);
spin_unlock_irq(&nlru->lock);
return ret;
}
unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
list_lru_walk_cb isolate, void *cb_arg,
unsigned long *nr_to_walk)
{
long isolated = 0;
int memcg_idx;
isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
nr_to_walk);
if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
for_each_memcg_cache_index(memcg_idx) {
struct list_lru_node *nlru = &lru->node[nid];
spin_lock(&nlru->lock);
isolated += __list_lru_walk_one(nlru, memcg_idx,
isolate, cb_arg,
nr_to_walk);
spin_unlock(&nlru->lock);
if (*nr_to_walk <= 0)
break;
}
}
return isolated;
}
EXPORT_SYMBOL_GPL(list_lru_walk_node);
static void init_one_lru(struct list_lru_one *l)
{
INIT_LIST_HEAD(&l->list);
l->nr_items = 0;
}
#ifdef CONFIG_MEMCG_KMEM
static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
int begin, int end)
{
int i;
for (i = begin; i < end; i++)
kfree(memcg_lrus->lru[i]);
}
static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus,
int begin, int end)
{
int i;
for (i = begin; i < end; i++) {
struct list_lru_one *l;
l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL);
if (!l)
goto fail;
init_one_lru(l);
memcg_lrus->lru[i] = l;
}
return 0;
fail:
__memcg_destroy_list_lru_node(memcg_lrus, begin, i);
return -ENOMEM;
}
static int memcg_init_list_lru_node(struct list_lru_node *nlru)
{
struct list_lru_memcg *memcg_lrus;
int size = memcg_nr_cache_ids;
memcg_lrus = kvmalloc(sizeof(*memcg_lrus) +
size * sizeof(void *), GFP_KERNEL);
if (!memcg_lrus)
return -ENOMEM;
if (__memcg_init_list_lru_node(memcg_lrus, 0, size)) {
kvfree(memcg_lrus);
return -ENOMEM;
}
RCU_INIT_POINTER(nlru->memcg_lrus, memcg_lrus);
return 0;
}
static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
{
struct list_lru_memcg *memcg_lrus;
/*
* This is called when shrinker has already been unregistered,
* and nobody can use it. So, there is no need to use kvfree_rcu().
*/
memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, true);
__memcg_destroy_list_lru_node(memcg_lrus, 0, memcg_nr_cache_ids);
kvfree(memcg_lrus);
}
static void kvfree_rcu(struct rcu_head *head)
{
struct list_lru_memcg *mlru;
mlru = container_of(head, struct list_lru_memcg, rcu);
kvfree(mlru);
}
static int memcg_update_list_lru_node(struct list_lru_node *nlru,
int old_size, int new_size)
{
struct list_lru_memcg *old, *new;
BUG_ON(old_size > new_size);
old = rcu_dereference_protected(nlru->memcg_lrus,
lockdep_is_held(&list_lrus_mutex));
new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL);
if (!new)
return -ENOMEM;
if (__memcg_init_list_lru_node(new, old_size, new_size)) {
kvfree(new);
return -ENOMEM;
}
memcpy(&new->lru, &old->lru, old_size * sizeof(void *));
/*
* The locking below allows readers that hold nlru->lock avoid taking
* rcu_read_lock (see list_lru_from_memcg_idx).
*
* Since list_lru_{add,del} may be called under an IRQ-safe lock,
* we have to use IRQ-safe primitives here to avoid deadlock.
*/
spin_lock_irq(&nlru->lock);
rcu_assign_pointer(nlru->memcg_lrus, new);
spin_unlock_irq(&nlru->lock);
call_rcu(&old->rcu, kvfree_rcu);
return 0;
}
static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru,
int old_size, int new_size)
{
struct list_lru_memcg *memcg_lrus;
memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus,
lockdep_is_held(&list_lrus_mutex));
/* do not bother shrinking the array back to the old size, because we
* cannot handle allocation failures here */
__memcg_destroy_list_lru_node(memcg_lrus, old_size, new_size);
}
static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
{
int i;
lru->memcg_aware = memcg_aware;
if (!memcg_aware)
return 0;
for_each_node(i) {
if (memcg_init_list_lru_node(&lru->node[i]))
goto fail;
}
return 0;
fail:
for (i = i - 1; i >= 0; i--) {
if (!lru->node[i].memcg_lrus)
continue;
memcg_destroy_list_lru_node(&lru->node[i]);
}
return -ENOMEM;
}
static void memcg_destroy_list_lru(struct list_lru *lru)
{
int i;
if (!list_lru_memcg_aware(lru))
return;
for_each_node(i)
memcg_destroy_list_lru_node(&lru->node[i]);
}
static int memcg_update_list_lru(struct list_lru *lru,
int old_size, int new_size)
{
int i;
if (!list_lru_memcg_aware(lru))
return 0;
for_each_node(i) {
if (memcg_update_list_lru_node(&lru->node[i],
old_size, new_size))
goto fail;
}
return 0;
fail:
for (i = i - 1; i >= 0; i--) {
if (!lru->node[i].memcg_lrus)
continue;
memcg_cancel_update_list_lru_node(&lru->node[i],
old_size, new_size);
}
return -ENOMEM;
}
static void memcg_cancel_update_list_lru(struct list_lru *lru,
int old_size, int new_size)
{
int i;
if (!list_lru_memcg_aware(lru))
return;
for_each_node(i)
memcg_cancel_update_list_lru_node(&lru->node[i],
old_size, new_size);
}
int memcg_update_all_list_lrus(int new_size)
{
int ret = 0;
struct list_lru *lru;
int old_size = memcg_nr_cache_ids;
mutex_lock(&list_lrus_mutex);
list_for_each_entry(lru, &list_lrus, list) {
ret = memcg_update_list_lru(lru, old_size, new_size);
if (ret)
goto fail;
}
out:
mutex_unlock(&list_lrus_mutex);
return ret;
fail:
list_for_each_entry_continue_reverse(lru, &list_lrus, list)
memcg_cancel_update_list_lru(lru, old_size, new_size);
goto out;
}
static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
int src_idx, struct mem_cgroup *dst_memcg)
{
struct list_lru_node *nlru = &lru->node[nid];
int dst_idx = dst_memcg->kmemcg_id;
struct list_lru_one *src, *dst;
bool set;
/*
* Since list_lru_{add,del} may be called under an IRQ-safe lock,
* we have to use IRQ-safe primitives here to avoid deadlock.
*/
spin_lock_irq(&nlru->lock);
src = list_lru_from_memcg_idx(nlru, src_idx);
dst = list_lru_from_memcg_idx(nlru, dst_idx);
list_splice_init(&src->list, &dst->list);
set = (!dst->nr_items && src->nr_items);
dst->nr_items += src->nr_items;
if (set)
memcg_set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
src->nr_items = 0;
spin_unlock_irq(&nlru->lock);
}
static void memcg_drain_list_lru(struct list_lru *lru,
int src_idx, struct mem_cgroup *dst_memcg)
{
int i;
if (!list_lru_memcg_aware(lru))
return;
for_each_node(i)
memcg_drain_list_lru_node(lru, i, src_idx, dst_memcg);
}
void memcg_drain_all_list_lrus(int src_idx, struct mem_cgroup *dst_memcg)
{
struct list_lru *lru;
mutex_lock(&list_lrus_mutex);
list_for_each_entry(lru, &list_lrus, list)
memcg_drain_list_lru(lru, src_idx, dst_memcg);
mutex_unlock(&list_lrus_mutex);
}
#else
static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
{
return 0;
}
static void memcg_destroy_list_lru(struct list_lru *lru)
{
}
#endif /* CONFIG_MEMCG_KMEM */
int __list_lru_init(struct list_lru *lru, bool memcg_aware,
struct lock_class_key *key, struct shrinker *shrinker)
{
int i;
int err = -ENOMEM;
#ifdef CONFIG_MEMCG_KMEM
if (shrinker)
lru->shrinker_id = shrinker->id;
else
lru->shrinker_id = -1;
#endif
memcg_get_cache_ids();
lru->node = kcalloc(nr_node_ids, sizeof(*lru->node), GFP_KERNEL);
if (!lru->node)
goto out;
for_each_node(i) {
spin_lock_init(&lru->node[i].lock);
if (key)
lockdep_set_class(&lru->node[i].lock, key);
init_one_lru(&lru->node[i].lru);
}
err = memcg_init_list_lru(lru, memcg_aware);
if (err) {
kfree(lru->node);
/* Do this so a list_lru_destroy() doesn't crash: */
lru->node = NULL;
goto out;
}
list_lru_register(lru);
out:
memcg_put_cache_ids();
return err;
}
EXPORT_SYMBOL_GPL(__list_lru_init);
void list_lru_destroy(struct list_lru *lru)
{
/* Already destroyed or not yet initialized? */
if (!lru->node)
return;
memcg_get_cache_ids();
list_lru_unregister(lru);
memcg_destroy_list_lru(lru);
kfree(lru->node);
lru->node = NULL;
#ifdef CONFIG_MEMCG_KMEM
lru->shrinker_id = -1;
#endif
memcg_put_cache_ids();
}
EXPORT_SYMBOL_GPL(list_lru_destroy);