4 * Author: Alexander Potapenko <glider@google.com>
5 * Copyright (C) 2016 Google, Inc.
7 * Based on code by Dmitry Chernenkov.
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * version 2 as published by the Free Software Foundation.
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
20 #include <linux/gfp.h>
21 #include <linux/hash.h>
22 #include <linux/kernel.h>
24 #include <linux/percpu.h>
25 #include <linux/printk.h>
26 #include <linux/shrinker.h>
27 #include <linux/slab.h>
28 #include <linux/string.h>
29 #include <linux/types.h>
34 /* Data structure and operations for quarantine queues. */
37 * Each queue is a signle-linked list, which also stores the total size of
38 * objects inside of it.
41 struct qlist_node *head;
42 struct qlist_node *tail;
46 #define QLIST_INIT { NULL, NULL, 0 }
48 static bool qlist_empty(struct qlist_head *q)
53 static void qlist_init(struct qlist_head *q)
55 q->head = q->tail = NULL;
59 static void qlist_put(struct qlist_head *q, struct qlist_node *qlink,
62 if (unlikely(qlist_empty(q)))
65 q->tail->next = qlink;
71 static void qlist_move_all(struct qlist_head *from, struct qlist_head *to)
73 if (unlikely(qlist_empty(from)))
76 if (qlist_empty(to)) {
82 to->tail->next = from->head;
83 to->tail = from->tail;
84 to->bytes += from->bytes;
89 static void qlist_move(struct qlist_head *from, struct qlist_node *last,
90 struct qlist_head *to, size_t size)
92 if (unlikely(last == from->tail)) {
93 qlist_move_all(from, to);
97 to->head = from->head;
99 to->tail->next = from->head;
101 from->head = last->next;
109 * The object quarantine consists of per-cpu queues and a global queue,
110 * guarded by quarantine_lock.
112 static DEFINE_PER_CPU(struct qlist_head, cpu_quarantine);
114 static struct qlist_head global_quarantine;
115 static DEFINE_SPINLOCK(quarantine_lock);
117 /* Maximum size of the global queue. */
118 static unsigned long quarantine_size;
121 * The fraction of physical memory the quarantine is allowed to occupy.
122 * Quarantine doesn't support memory shrinker with SLAB allocator, so we keep
123 * the ratio low to avoid OOM.
125 #define QUARANTINE_FRACTION 32
127 #define QUARANTINE_LOW_SIZE (READ_ONCE(quarantine_size) * 3 / 4)
128 #define QUARANTINE_PERCPU_SIZE (1 << 20)
130 static struct kmem_cache *qlink_to_cache(struct qlist_node *qlink)
132 return virt_to_head_page(qlink)->slab_cache;
135 static void *qlink_to_object(struct qlist_node *qlink, struct kmem_cache *cache)
137 struct kasan_free_meta *free_info =
138 container_of(qlink, struct kasan_free_meta,
141 return ((void *)free_info) - cache->kasan_info.free_meta_offset;
144 static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
146 void *object = qlink_to_object(qlink, cache);
149 if (IS_ENABLED(CONFIG_SLAB))
150 local_irq_save(flags);
152 ___cache_free(cache, object, _THIS_IP_);
154 if (IS_ENABLED(CONFIG_SLAB))
155 local_irq_restore(flags);
158 static void qlist_free_all(struct qlist_head *q, struct kmem_cache *cache)
160 struct qlist_node *qlink;
162 if (unlikely(qlist_empty(q)))
167 struct kmem_cache *obj_cache =
168 cache ? cache : qlink_to_cache(qlink);
169 struct qlist_node *next = qlink->next;
171 qlink_free(qlink, obj_cache);
177 void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache)
180 struct qlist_head *q;
181 struct qlist_head temp = QLIST_INIT;
183 local_irq_save(flags);
185 q = this_cpu_ptr(&cpu_quarantine);
186 qlist_put(q, &info->quarantine_link, cache->size);
187 if (unlikely(q->bytes > QUARANTINE_PERCPU_SIZE))
188 qlist_move_all(q, &temp);
190 local_irq_restore(flags);
192 if (unlikely(!qlist_empty(&temp))) {
193 spin_lock_irqsave(&quarantine_lock, flags);
194 qlist_move_all(&temp, &global_quarantine);
195 spin_unlock_irqrestore(&quarantine_lock, flags);
199 void quarantine_reduce(void)
201 size_t new_quarantine_size, percpu_quarantines;
203 struct qlist_head to_free = QLIST_INIT;
204 size_t size_to_free = 0;
205 struct qlist_node *last;
207 if (likely(READ_ONCE(global_quarantine.bytes) <=
208 READ_ONCE(quarantine_size)))
211 spin_lock_irqsave(&quarantine_lock, flags);
214 * Update quarantine size in case of hotplug. Allocate a fraction of
215 * the installed memory to quarantine minus per-cpu queue limits.
217 new_quarantine_size = (READ_ONCE(totalram_pages) << PAGE_SHIFT) /
219 percpu_quarantines = QUARANTINE_PERCPU_SIZE * num_online_cpus();
220 new_quarantine_size = (new_quarantine_size < percpu_quarantines) ?
221 0 : new_quarantine_size - percpu_quarantines;
222 WRITE_ONCE(quarantine_size, new_quarantine_size);
224 last = global_quarantine.head;
226 struct kmem_cache *cache = qlink_to_cache(last);
228 size_to_free += cache->size;
229 if (!last->next || size_to_free >
230 global_quarantine.bytes - QUARANTINE_LOW_SIZE)
234 qlist_move(&global_quarantine, last, &to_free, size_to_free);
236 spin_unlock_irqrestore(&quarantine_lock, flags);
238 qlist_free_all(&to_free, NULL);
241 static void qlist_move_cache(struct qlist_head *from,
242 struct qlist_head *to,
243 struct kmem_cache *cache)
245 struct qlist_node *curr;
247 if (unlikely(qlist_empty(from)))
253 struct qlist_node *next = curr->next;
254 struct kmem_cache *obj_cache = qlink_to_cache(curr);
256 if (obj_cache == cache)
257 qlist_put(to, curr, obj_cache->size);
259 qlist_put(from, curr, obj_cache->size);
265 static void per_cpu_remove_cache(void *arg)
267 struct kmem_cache *cache = arg;
268 struct qlist_head to_free = QLIST_INIT;
269 struct qlist_head *q;
271 q = this_cpu_ptr(&cpu_quarantine);
272 qlist_move_cache(q, &to_free, cache);
273 qlist_free_all(&to_free, cache);
276 void quarantine_remove_cache(struct kmem_cache *cache)
279 struct qlist_head to_free = QLIST_INIT;
281 on_each_cpu(per_cpu_remove_cache, cache, 1);
283 spin_lock_irqsave(&quarantine_lock, flags);
284 qlist_move_cache(&global_quarantine, &to_free, cache);
285 spin_unlock_irqrestore(&quarantine_lock, flags);
287 qlist_free_all(&to_free, cache);