1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * SLUB: A slab allocator that limits cache line use instead of queuing |
4 | * objects in per cpu and per node lists. |
5 | * |
6 | * The allocator synchronizes using per slab locks or atomic operatios |
7 | * and only uses a centralized lock to manage a pool of partial slabs. |
8 | * |
9 | * (C) 2007 SGI, Christoph Lameter |
10 | * (C) 2011 Linux Foundation, Christoph Lameter |
11 | */ |
12 | |
13 | #include <linux/mm.h> |
14 | #include <linux/swap.h> /* struct reclaim_state */ |
15 | #include <linux/module.h> |
16 | #include <linux/bit_spinlock.h> |
17 | #include <linux/interrupt.h> |
18 | #include <linux/bitops.h> |
19 | #include <linux/slab.h> |
20 | #include "slab.h" |
21 | #include <linux/proc_fs.h> |
22 | #include <linux/seq_file.h> |
23 | #include <linux/kasan.h> |
24 | #include <linux/cpu.h> |
25 | #include <linux/cpuset.h> |
26 | #include <linux/mempolicy.h> |
27 | #include <linux/ctype.h> |
28 | #include <linux/debugobjects.h> |
29 | #include <linux/kallsyms.h> |
30 | #include <linux/memory.h> |
31 | #include <linux/math64.h> |
32 | #include <linux/fault-inject.h> |
33 | #include <linux/stacktrace.h> |
34 | #include <linux/prefetch.h> |
35 | #include <linux/memcontrol.h> |
36 | #include <linux/random.h> |
37 | |
38 | #include <trace/events/kmem.h> |
39 | |
40 | #include "internal.h" |
41 | |
42 | /* |
43 | * Lock order: |
44 | * 1. slab_mutex (Global Mutex) |
45 | * 2. node->list_lock |
46 | * 3. slab_lock(page) (Only on some arches and for debugging) |
47 | * |
48 | * slab_mutex |
49 | * |
50 | * The role of the slab_mutex is to protect the list of all the slabs |
51 | * and to synchronize major metadata changes to slab cache structures. |
52 | * |
53 | * The slab_lock is only used for debugging and on arches that do not |
54 | * have the ability to do a cmpxchg_double. It only protects: |
55 | * A. page->freelist -> List of object free in a page |
56 | * B. page->inuse -> Number of objects in use |
57 | * C. page->objects -> Number of objects in page |
58 | * D. page->frozen -> frozen state |
59 | * |
60 | * If a slab is frozen then it is exempt from list management. It is not |
61 | * on any list. The processor that froze the slab is the one who can |
62 | * perform list operations on the page. Other processors may put objects |
63 | * onto the freelist but the processor that froze the slab is the only |
64 | * one that can retrieve the objects from the page's freelist. |
65 | * |
66 | * The list_lock protects the partial and full list on each node and |
67 | * the partial slab counter. If taken then no new slabs may be added or |
68 | * removed from the lists nor make the number of partial slabs be modified. |
69 | * (Note that the total number of slabs is an atomic value that may be |
70 | * modified without taking the list lock). |
71 | * |
72 | * The list_lock is a centralized lock and thus we avoid taking it as |
73 | * much as possible. As long as SLUB does not have to handle partial |
74 | * slabs, operations can continue without any centralized lock. F.e. |
75 | * allocating a long series of objects that fill up slabs does not require |
76 | * the list lock. |
77 | * Interrupts are disabled during allocation and deallocation in order to |
78 | * make the slab allocator safe to use in the context of an irq. In addition |
79 | * interrupts are disabled to ensure that the processor does not change |
80 | * while handling per_cpu slabs, due to kernel preemption. |
81 | * |
82 | * SLUB assigns one slab for allocation to each processor. |
83 | * Allocations only occur from these slabs called cpu slabs. |
84 | * |
85 | * Slabs with free elements are kept on a partial list and during regular |
86 | * operations no list for full slabs is used. If an object in a full slab is |
87 | * freed then the slab will show up again on the partial lists. |
88 | * We track full slabs for debugging purposes though because otherwise we |
89 | * cannot scan all objects. |
90 | * |
91 | * Slabs are freed when they become empty. Teardown and setup is |
92 | * minimal so we rely on the page allocators per cpu caches for |
93 | * fast frees and allocs. |
94 | * |
95 | * Overloading of page flags that are otherwise used for LRU management. |
96 | * |
97 | * PageActive The slab is frozen and exempt from list processing. |
98 | * This means that the slab is dedicated to a purpose |
99 | * such as satisfying allocations for a specific |
100 | * processor. Objects may be freed in the slab while |
101 | * it is frozen but slab_free will then skip the usual |
102 | * list operations. It is up to the processor holding |
103 | * the slab to integrate the slab into the slab lists |
104 | * when the slab is no longer needed. |
105 | * |
106 | * One use of this flag is to mark slabs that are |
107 | * used for allocations. Then such a slab becomes a cpu |
108 | * slab. The cpu slab may be equipped with an additional |
109 | * freelist that allows lockless access to |
110 | * free objects in addition to the regular freelist |
111 | * that requires the slab lock. |
112 | * |
113 | * PageError Slab requires special handling due to debug |
114 | * options set. This moves slab handling out of |
115 | * the fast path and disables lockless freelists. |
116 | */ |
117 | |
118 | static inline int kmem_cache_debug(struct kmem_cache *s) |
119 | { |
120 | #ifdef CONFIG_SLUB_DEBUG |
121 | return unlikely(s->flags & SLAB_DEBUG_FLAGS); |
122 | #else |
123 | return 0; |
124 | #endif |
125 | } |
126 | |
127 | void *fixup_red_left(struct kmem_cache *s, void *p) |
128 | { |
129 | if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) |
130 | p += s->red_left_pad; |
131 | |
132 | return p; |
133 | } |
134 | |
135 | static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) |
136 | { |
137 | #ifdef CONFIG_SLUB_CPU_PARTIAL |
138 | return !kmem_cache_debug(s); |
139 | #else |
140 | return false; |
141 | #endif |
142 | } |
143 | |
144 | /* |
145 | * Issues still to be resolved: |
146 | * |
147 | * - Support PAGE_ALLOC_DEBUG. Should be easy to do. |
148 | * |
149 | * - Variable sizing of the per node arrays |
150 | */ |
151 | |
152 | /* Enable to test recovery from slab corruption on boot */ |
153 | #undef SLUB_RESILIENCY_TEST |
154 | |
155 | /* Enable to log cmpxchg failures */ |
156 | #undef SLUB_DEBUG_CMPXCHG |
157 | |
158 | /* |
159 | * Mininum number of partial slabs. These will be left on the partial |
160 | * lists even if they are empty. kmem_cache_shrink may reclaim them. |
161 | */ |
162 | #define MIN_PARTIAL 5 |
163 | |
164 | /* |
165 | * Maximum number of desirable partial slabs. |
166 | * The existence of more partial slabs makes kmem_cache_shrink |
167 | * sort the partial list by the number of objects in use. |
168 | */ |
169 | #define MAX_PARTIAL 10 |
170 | |
171 | #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \ |
172 | SLAB_POISON | SLAB_STORE_USER) |
173 | |
174 | /* |
175 | * These debug flags cannot use CMPXCHG because there might be consistency |
176 | * issues when checking or reading debug information |
177 | */ |
178 | #define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \ |
179 | SLAB_TRACE) |
180 | |
181 | |
182 | /* |
183 | * Debugging flags that require metadata to be stored in the slab. These get |
184 | * disabled when slub_debug=O is used and a cache's min order increases with |
185 | * metadata. |
186 | */ |
187 | #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER) |
188 | |
189 | #define OO_SHIFT 16 |
190 | #define OO_MASK ((1 << OO_SHIFT) - 1) |
191 | #define MAX_OBJS_PER_PAGE 32767 /* since page.objects is u15 */ |
192 | |
193 | /* Internal SLUB flags */ |
194 | /* Poison object */ |
195 | #define __OBJECT_POISON ((slab_flags_t __force)0x80000000U) |
196 | /* Use cmpxchg_double */ |
197 | #define __CMPXCHG_DOUBLE ((slab_flags_t __force)0x40000000U) |
198 | |
199 | /* |
200 | * Tracking user of a slab. |
201 | */ |
202 | #define TRACK_ADDRS_COUNT 16 |
203 | struct track { |
204 | unsigned long addr; /* Called from address */ |
205 | #ifdef CONFIG_STACKTRACE |
206 | unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */ |
207 | #endif |
208 | int cpu; /* Was running on cpu */ |
209 | int pid; /* Pid context */ |
210 | unsigned long when; /* When did the operation occur */ |
211 | }; |
212 | |
213 | enum track_item { TRACK_ALLOC, TRACK_FREE }; |
214 | |
215 | #ifdef CONFIG_SYSFS |
216 | static int sysfs_slab_add(struct kmem_cache *); |
217 | static int sysfs_slab_alias(struct kmem_cache *, const char *); |
218 | static void memcg_propagate_slab_attrs(struct kmem_cache *s); |
219 | static void sysfs_slab_remove(struct kmem_cache *s); |
220 | #else |
221 | static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; } |
222 | static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) |
223 | { return 0; } |
224 | static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { } |
225 | static inline void sysfs_slab_remove(struct kmem_cache *s) { } |
226 | #endif |
227 | |
228 | static inline void stat(const struct kmem_cache *s, enum stat_item si) |
229 | { |
230 | #ifdef CONFIG_SLUB_STATS |
231 | /* |
232 | * The rmw is racy on a preemptible kernel but this is acceptable, so |
233 | * avoid this_cpu_add()'s irq-disable overhead. |
234 | */ |
235 | raw_cpu_inc(s->cpu_slab->stat[si]); |
236 | #endif |
237 | } |
238 | |
239 | /******************************************************************** |
240 | * Core slab cache functions |
241 | *******************************************************************/ |
242 | |
243 | /* |
244 | * Returns freelist pointer (ptr). With hardening, this is obfuscated |
245 | * with an XOR of the address where the pointer is held and a per-cache |
246 | * random number. |
247 | */ |
248 | static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr, |
249 | unsigned long ptr_addr) |
250 | { |
251 | #ifdef CONFIG_SLAB_FREELIST_HARDENED |
252 | /* |
253 | * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. |
254 | * Normally, this doesn't cause any issues, as both set_freepointer() |
255 | * and get_freepointer() are called with a pointer with the same tag. |
256 | * However, there are some issues with CONFIG_SLUB_DEBUG code. For |
257 | * example, when __free_slub() iterates over objects in a cache, it |
258 | * passes untagged pointers to check_object(). check_object() in turns |
259 | * calls get_freepointer() with an untagged pointer, which causes the |
260 | * freepointer to be restored incorrectly. |
261 | */ |
262 | return (void *)((unsigned long)ptr ^ s->random ^ |
263 | (unsigned long)kasan_reset_tag((void *)ptr_addr)); |
264 | #else |
265 | return ptr; |
266 | #endif |
267 | } |
268 | |
269 | /* Returns the freelist pointer recorded at location ptr_addr. */ |
270 | static inline void *freelist_dereference(const struct kmem_cache *s, |
271 | void *ptr_addr) |
272 | { |
273 | return freelist_ptr(s, (void *)*(unsigned long *)(ptr_addr), |
274 | (unsigned long)ptr_addr); |
275 | } |
276 | |
277 | static inline void *get_freepointer(struct kmem_cache *s, void *object) |
278 | { |
279 | return freelist_dereference(s, object + s->offset); |
280 | } |
281 | |
282 | static void prefetch_freepointer(const struct kmem_cache *s, void *object) |
283 | { |
284 | prefetch(object + s->offset); |
285 | } |
286 | |
287 | static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) |
288 | { |
289 | unsigned long freepointer_addr; |
290 | void *p; |
291 | |
292 | if (!debug_pagealloc_enabled()) |
293 | return get_freepointer(s, object); |
294 | |
295 | freepointer_addr = (unsigned long)object + s->offset; |
296 | probe_kernel_read(&p, (void **)freepointer_addr, sizeof(p)); |
297 | return freelist_ptr(s, p, freepointer_addr); |
298 | } |
299 | |
300 | static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) |
301 | { |
302 | unsigned long freeptr_addr = (unsigned long)object + s->offset; |
303 | |
304 | #ifdef CONFIG_SLAB_FREELIST_HARDENED |
305 | BUG_ON(object == fp); /* naive detection of double free or corruption */ |
306 | #endif |
307 | |
308 | *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr); |
309 | } |
310 | |
311 | /* Loop over all objects in a slab */ |
312 | #define for_each_object(__p, __s, __addr, __objects) \ |
313 | for (__p = fixup_red_left(__s, __addr); \ |
314 | __p < (__addr) + (__objects) * (__s)->size; \ |
315 | __p += (__s)->size) |
316 | |
317 | /* Determine object index from a given position */ |
318 | static inline unsigned int slab_index(void *p, struct kmem_cache *s, void *addr) |
319 | { |
320 | return (kasan_reset_tag(p) - addr) / s->size; |
321 | } |
322 | |
323 | static inline unsigned int order_objects(unsigned int order, unsigned int size) |
324 | { |
325 | return ((unsigned int)PAGE_SIZE << order) / size; |
326 | } |
327 | |
328 | static inline struct kmem_cache_order_objects oo_make(unsigned int order, |
329 | unsigned int size) |
330 | { |
331 | struct kmem_cache_order_objects x = { |
332 | (order << OO_SHIFT) + order_objects(order, size) |
333 | }; |
334 | |
335 | return x; |
336 | } |
337 | |
338 | static inline unsigned int oo_order(struct kmem_cache_order_objects x) |
339 | { |
340 | return x.x >> OO_SHIFT; |
341 | } |
342 | |
343 | static inline unsigned int oo_objects(struct kmem_cache_order_objects x) |
344 | { |
345 | return x.x & OO_MASK; |
346 | } |
347 | |
348 | /* |
349 | * Per slab locking using the pagelock |
350 | */ |
351 | static __always_inline void slab_lock(struct page *page) |
352 | { |
353 | VM_BUG_ON_PAGE(PageTail(page), page); |
354 | bit_spin_lock(PG_locked, &page->flags); |
355 | } |
356 | |
357 | static __always_inline void slab_unlock(struct page *page) |
358 | { |
359 | VM_BUG_ON_PAGE(PageTail(page), page); |
360 | __bit_spin_unlock(PG_locked, &page->flags); |
361 | } |
362 | |
363 | /* Interrupts must be disabled (for the fallback code to work right) */ |
364 | static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, |
365 | void *freelist_old, unsigned long counters_old, |
366 | void *freelist_new, unsigned long counters_new, |
367 | const char *n) |
368 | { |
369 | VM_BUG_ON(!irqs_disabled()); |
370 | #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ |
371 | defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) |
372 | if (s->flags & __CMPXCHG_DOUBLE) { |
373 | if (cmpxchg_double(&page->freelist, &page->counters, |
374 | freelist_old, counters_old, |
375 | freelist_new, counters_new)) |
376 | return true; |
377 | } else |
378 | #endif |
379 | { |
380 | slab_lock(page); |
381 | if (page->freelist == freelist_old && |
382 | page->counters == counters_old) { |
383 | page->freelist = freelist_new; |
384 | page->counters = counters_new; |
385 | slab_unlock(page); |
386 | return true; |
387 | } |
388 | slab_unlock(page); |
389 | } |
390 | |
391 | cpu_relax(); |
392 | stat(s, CMPXCHG_DOUBLE_FAIL); |
393 | |
394 | #ifdef SLUB_DEBUG_CMPXCHG |
395 | pr_info("%s %s: cmpxchg double redo " , n, s->name); |
396 | #endif |
397 | |
398 | return false; |
399 | } |
400 | |
401 | static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page, |
402 | void *freelist_old, unsigned long counters_old, |
403 | void *freelist_new, unsigned long counters_new, |
404 | const char *n) |
405 | { |
406 | #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ |
407 | defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) |
408 | if (s->flags & __CMPXCHG_DOUBLE) { |
409 | if (cmpxchg_double(&page->freelist, &page->counters, |
410 | freelist_old, counters_old, |
411 | freelist_new, counters_new)) |
412 | return true; |
413 | } else |
414 | #endif |
415 | { |
416 | unsigned long flags; |
417 | |
418 | local_irq_save(flags); |
419 | slab_lock(page); |
420 | if (page->freelist == freelist_old && |
421 | page->counters == counters_old) { |
422 | page->freelist = freelist_new; |
423 | page->counters = counters_new; |
424 | slab_unlock(page); |
425 | local_irq_restore(flags); |
426 | return true; |
427 | } |
428 | slab_unlock(page); |
429 | local_irq_restore(flags); |
430 | } |
431 | |
432 | cpu_relax(); |
433 | stat(s, CMPXCHG_DOUBLE_FAIL); |
434 | |
435 | #ifdef SLUB_DEBUG_CMPXCHG |
436 | pr_info("%s %s: cmpxchg double redo " , n, s->name); |
437 | #endif |
438 | |
439 | return false; |
440 | } |
441 | |
442 | #ifdef CONFIG_SLUB_DEBUG |
443 | /* |
444 | * Determine a map of object in use on a page. |
445 | * |
446 | * Node listlock must be held to guarantee that the page does |
447 | * not vanish from under us. |
448 | */ |
449 | static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map) |
450 | { |
451 | void *p; |
452 | void *addr = page_address(page); |
453 | |
454 | for (p = page->freelist; p; p = get_freepointer(s, p)) |
455 | set_bit(slab_index(p, s, addr), map); |
456 | } |
457 | |
458 | static inline unsigned int size_from_object(struct kmem_cache *s) |
459 | { |
460 | if (s->flags & SLAB_RED_ZONE) |
461 | return s->size - s->red_left_pad; |
462 | |
463 | return s->size; |
464 | } |
465 | |
466 | static inline void *restore_red_left(struct kmem_cache *s, void *p) |
467 | { |
468 | if (s->flags & SLAB_RED_ZONE) |
469 | p -= s->red_left_pad; |
470 | |
471 | return p; |
472 | } |
473 | |
474 | /* |
475 | * Debug settings: |
476 | */ |
477 | #if defined(CONFIG_SLUB_DEBUG_ON) |
478 | static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS; |
479 | #else |
480 | static slab_flags_t slub_debug; |
481 | #endif |
482 | |
483 | static char *slub_debug_slabs; |
484 | static int disable_higher_order_debug; |
485 | |
486 | /* |
487 | * slub is about to manipulate internal object metadata. This memory lies |
488 | * outside the range of the allocated object, so accessing it would normally |
489 | * be reported by kasan as a bounds error. metadata_access_enable() is used |
490 | * to tell kasan that these accesses are OK. |
491 | */ |
492 | static inline void metadata_access_enable(void) |
493 | { |
494 | kasan_disable_current(); |
495 | } |
496 | |
497 | static inline void metadata_access_disable(void) |
498 | { |
499 | kasan_enable_current(); |
500 | } |
501 | |
502 | /* |
503 | * Object debugging |
504 | */ |
505 | |
506 | /* Verify that a pointer has an address that is valid within a slab page */ |
507 | static inline int check_valid_pointer(struct kmem_cache *s, |
508 | struct page *page, void *object) |
509 | { |
510 | void *base; |
511 | |
512 | if (!object) |
513 | return 1; |
514 | |
515 | base = page_address(page); |
516 | object = kasan_reset_tag(object); |
517 | object = restore_red_left(s, object); |
518 | if (object < base || object >= base + page->objects * s->size || |
519 | (object - base) % s->size) { |
520 | return 0; |
521 | } |
522 | |
523 | return 1; |
524 | } |
525 | |
526 | static void print_section(char *level, char *text, u8 *addr, |
527 | unsigned int length) |
528 | { |
529 | metadata_access_enable(); |
530 | print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr, |
531 | length, 1); |
532 | metadata_access_disable(); |
533 | } |
534 | |
535 | static struct track *get_track(struct kmem_cache *s, void *object, |
536 | enum track_item alloc) |
537 | { |
538 | struct track *p; |
539 | |
540 | if (s->offset) |
541 | p = object + s->offset + sizeof(void *); |
542 | else |
543 | p = object + s->inuse; |
544 | |
545 | return p + alloc; |
546 | } |
547 | |
548 | static void set_track(struct kmem_cache *s, void *object, |
549 | enum track_item alloc, unsigned long addr) |
550 | { |
551 | struct track *p = get_track(s, object, alloc); |
552 | |
553 | if (addr) { |
554 | #ifdef CONFIG_STACKTRACE |
555 | struct stack_trace trace; |
556 | int i; |
557 | |
558 | trace.nr_entries = 0; |
559 | trace.max_entries = TRACK_ADDRS_COUNT; |
560 | trace.entries = p->addrs; |
561 | trace.skip = 3; |
562 | metadata_access_enable(); |
563 | save_stack_trace(&trace); |
564 | metadata_access_disable(); |
565 | |
566 | /* See rant in lockdep.c */ |
567 | if (trace.nr_entries != 0 && |
568 | trace.entries[trace.nr_entries - 1] == ULONG_MAX) |
569 | trace.nr_entries--; |
570 | |
571 | for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++) |
572 | p->addrs[i] = 0; |
573 | #endif |
574 | p->addr = addr; |
575 | p->cpu = smp_processor_id(); |
576 | p->pid = current->pid; |
577 | p->when = jiffies; |
578 | } else |
579 | memset(p, 0, sizeof(struct track)); |
580 | } |
581 | |
582 | static void init_tracking(struct kmem_cache *s, void *object) |
583 | { |
584 | if (!(s->flags & SLAB_STORE_USER)) |
585 | return; |
586 | |
587 | set_track(s, object, TRACK_FREE, 0UL); |
588 | set_track(s, object, TRACK_ALLOC, 0UL); |
589 | } |
590 | |
591 | static void print_track(const char *s, struct track *t, unsigned long pr_time) |
592 | { |
593 | if (!t->addr) |
594 | return; |
595 | |
596 | pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n" , |
597 | s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid); |
598 | #ifdef CONFIG_STACKTRACE |
599 | { |
600 | int i; |
601 | for (i = 0; i < TRACK_ADDRS_COUNT; i++) |
602 | if (t->addrs[i]) |
603 | pr_err("\t%pS\n" , (void *)t->addrs[i]); |
604 | else |
605 | break; |
606 | } |
607 | #endif |
608 | } |
609 | |
610 | static void print_tracking(struct kmem_cache *s, void *object) |
611 | { |
612 | unsigned long pr_time = jiffies; |
613 | if (!(s->flags & SLAB_STORE_USER)) |
614 | return; |
615 | |
616 | print_track("Allocated" , get_track(s, object, TRACK_ALLOC), pr_time); |
617 | print_track("Freed" , get_track(s, object, TRACK_FREE), pr_time); |
618 | } |
619 | |
620 | static void print_page_info(struct page *page) |
621 | { |
622 | pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n" , |
623 | page, page->objects, page->inuse, page->freelist, page->flags); |
624 | |
625 | } |
626 | |
627 | static void slab_bug(struct kmem_cache *s, char *fmt, ...) |
628 | { |
629 | struct va_format vaf; |
630 | va_list args; |
631 | |
632 | va_start(args, fmt); |
633 | vaf.fmt = fmt; |
634 | vaf.va = &args; |
635 | pr_err("=============================================================================\n" ); |
636 | pr_err("BUG %s (%s): %pV\n" , s->name, print_tainted(), &vaf); |
637 | pr_err("-----------------------------------------------------------------------------\n\n" ); |
638 | |
639 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); |
640 | va_end(args); |
641 | } |
642 | |
643 | static void slab_fix(struct kmem_cache *s, char *fmt, ...) |
644 | { |
645 | struct va_format vaf; |
646 | va_list args; |
647 | |
648 | va_start(args, fmt); |
649 | vaf.fmt = fmt; |
650 | vaf.va = &args; |
651 | pr_err("FIX %s: %pV\n" , s->name, &vaf); |
652 | va_end(args); |
653 | } |
654 | |
655 | static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) |
656 | { |
657 | unsigned int off; /* Offset of last byte */ |
658 | u8 *addr = page_address(page); |
659 | |
660 | print_tracking(s, p); |
661 | |
662 | print_page_info(page); |
663 | |
664 | pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n" , |
665 | p, p - addr, get_freepointer(s, p)); |
666 | |
667 | if (s->flags & SLAB_RED_ZONE) |
668 | print_section(KERN_ERR, "Redzone " , p - s->red_left_pad, |
669 | s->red_left_pad); |
670 | else if (p > addr + 16) |
671 | print_section(KERN_ERR, "Bytes b4 " , p - 16, 16); |
672 | |
673 | print_section(KERN_ERR, "Object " , p, |
674 | min_t(unsigned int, s->object_size, PAGE_SIZE)); |
675 | if (s->flags & SLAB_RED_ZONE) |
676 | print_section(KERN_ERR, "Redzone " , p + s->object_size, |
677 | s->inuse - s->object_size); |
678 | |
679 | if (s->offset) |
680 | off = s->offset + sizeof(void *); |
681 | else |
682 | off = s->inuse; |
683 | |
684 | if (s->flags & SLAB_STORE_USER) |
685 | off += 2 * sizeof(struct track); |
686 | |
687 | off += kasan_metadata_size(s); |
688 | |
689 | if (off != size_from_object(s)) |
690 | /* Beginning of the filler is the free pointer */ |
691 | print_section(KERN_ERR, "Padding " , p + off, |
692 | size_from_object(s) - off); |
693 | |
694 | dump_stack(); |
695 | } |
696 | |
697 | void object_err(struct kmem_cache *s, struct page *page, |
698 | u8 *object, char *reason) |
699 | { |
700 | slab_bug(s, "%s" , reason); |
701 | print_trailer(s, page, object); |
702 | } |
703 | |
704 | static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, |
705 | const char *fmt, ...) |
706 | { |
707 | va_list args; |
708 | char buf[100]; |
709 | |
710 | va_start(args, fmt); |
711 | vsnprintf(buf, sizeof(buf), fmt, args); |
712 | va_end(args); |
713 | slab_bug(s, "%s" , buf); |
714 | print_page_info(page); |
715 | dump_stack(); |
716 | } |
717 | |
718 | static void init_object(struct kmem_cache *s, void *object, u8 val) |
719 | { |
720 | u8 *p = object; |
721 | |
722 | if (s->flags & SLAB_RED_ZONE) |
723 | memset(p - s->red_left_pad, val, s->red_left_pad); |
724 | |
725 | if (s->flags & __OBJECT_POISON) { |
726 | memset(p, POISON_FREE, s->object_size - 1); |
727 | p[s->object_size - 1] = POISON_END; |
728 | } |
729 | |
730 | if (s->flags & SLAB_RED_ZONE) |
731 | memset(p + s->object_size, val, s->inuse - s->object_size); |
732 | } |
733 | |
734 | static void restore_bytes(struct kmem_cache *s, char *message, u8 data, |
735 | void *from, void *to) |
736 | { |
737 | slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n" , from, to - 1, data); |
738 | memset(from, data, to - from); |
739 | } |
740 | |
741 | static int check_bytes_and_report(struct kmem_cache *s, struct page *page, |
742 | u8 *object, char *what, |
743 | u8 *start, unsigned int value, unsigned int bytes) |
744 | { |
745 | u8 *fault; |
746 | u8 *end; |
747 | |
748 | metadata_access_enable(); |
749 | fault = memchr_inv(start, value, bytes); |
750 | metadata_access_disable(); |
751 | if (!fault) |
752 | return 1; |
753 | |
754 | end = start + bytes; |
755 | while (end > fault && end[-1] == value) |
756 | end--; |
757 | |
758 | slab_bug(s, "%s overwritten" , what); |
759 | pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n" , |
760 | fault, end - 1, fault[0], value); |
761 | print_trailer(s, page, object); |
762 | |
763 | restore_bytes(s, what, value, fault, end); |
764 | return 0; |
765 | } |
766 | |
767 | /* |
768 | * Object layout: |
769 | * |
770 | * object address |
771 | * Bytes of the object to be managed. |
772 | * If the freepointer may overlay the object then the free |
773 | * pointer is the first word of the object. |
774 | * |
775 | * Poisoning uses 0x6b (POISON_FREE) and the last byte is |
776 | * 0xa5 (POISON_END) |
777 | * |
778 | * object + s->object_size |
779 | * Padding to reach word boundary. This is also used for Redzoning. |
780 | * Padding is extended by another word if Redzoning is enabled and |
781 | * object_size == inuse. |
782 | * |
783 | * We fill with 0xbb (RED_INACTIVE) for inactive objects and with |
784 | * 0xcc (RED_ACTIVE) for objects in use. |
785 | * |
786 | * object + s->inuse |
787 | * Meta data starts here. |
788 | * |
789 | * A. Free pointer (if we cannot overwrite object on free) |
790 | * B. Tracking data for SLAB_STORE_USER |
791 | * C. Padding to reach required alignment boundary or at mininum |
792 | * one word if debugging is on to be able to detect writes |
793 | * before the word boundary. |
794 | * |
795 | * Padding is done using 0x5a (POISON_INUSE) |
796 | * |
797 | * object + s->size |
798 | * Nothing is used beyond s->size. |
799 | * |
800 | * If slabcaches are merged then the object_size and inuse boundaries are mostly |
801 | * ignored. And therefore no slab options that rely on these boundaries |
802 | * may be used with merged slabcaches. |
803 | */ |
804 | |
805 | static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p) |
806 | { |
807 | unsigned long off = s->inuse; /* The end of info */ |
808 | |
809 | if (s->offset) |
810 | /* Freepointer is placed after the object. */ |
811 | off += sizeof(void *); |
812 | |
813 | if (s->flags & SLAB_STORE_USER) |
814 | /* We also have user information there */ |
815 | off += 2 * sizeof(struct track); |
816 | |
817 | off += kasan_metadata_size(s); |
818 | |
819 | if (size_from_object(s) == off) |
820 | return 1; |
821 | |
822 | return check_bytes_and_report(s, page, p, "Object padding" , |
823 | p + off, POISON_INUSE, size_from_object(s) - off); |
824 | } |
825 | |
826 | /* Check the pad bytes at the end of a slab page */ |
827 | static int slab_pad_check(struct kmem_cache *s, struct page *page) |
828 | { |
829 | u8 *start; |
830 | u8 *fault; |
831 | u8 *end; |
832 | u8 *pad; |
833 | int length; |
834 | int remainder; |
835 | |
836 | if (!(s->flags & SLAB_POISON)) |
837 | return 1; |
838 | |
839 | start = page_address(page); |
840 | length = PAGE_SIZE << compound_order(page); |
841 | end = start + length; |
842 | remainder = length % s->size; |
843 | if (!remainder) |
844 | return 1; |
845 | |
846 | pad = end - remainder; |
847 | metadata_access_enable(); |
848 | fault = memchr_inv(pad, POISON_INUSE, remainder); |
849 | metadata_access_disable(); |
850 | if (!fault) |
851 | return 1; |
852 | while (end > fault && end[-1] == POISON_INUSE) |
853 | end--; |
854 | |
855 | slab_err(s, page, "Padding overwritten. 0x%p-0x%p" , fault, end - 1); |
856 | print_section(KERN_ERR, "Padding " , pad, remainder); |
857 | |
858 | restore_bytes(s, "slab padding" , POISON_INUSE, fault, end); |
859 | return 0; |
860 | } |
861 | |
862 | static int check_object(struct kmem_cache *s, struct page *page, |
863 | void *object, u8 val) |
864 | { |
865 | u8 *p = object; |
866 | u8 *endobject = object + s->object_size; |
867 | |
868 | if (s->flags & SLAB_RED_ZONE) { |
869 | if (!check_bytes_and_report(s, page, object, "Redzone" , |
870 | object - s->red_left_pad, val, s->red_left_pad)) |
871 | return 0; |
872 | |
873 | if (!check_bytes_and_report(s, page, object, "Redzone" , |
874 | endobject, val, s->inuse - s->object_size)) |
875 | return 0; |
876 | } else { |
877 | if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) { |
878 | check_bytes_and_report(s, page, p, "Alignment padding" , |
879 | endobject, POISON_INUSE, |
880 | s->inuse - s->object_size); |
881 | } |
882 | } |
883 | |
884 | if (s->flags & SLAB_POISON) { |
885 | if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) && |
886 | (!check_bytes_and_report(s, page, p, "Poison" , p, |
887 | POISON_FREE, s->object_size - 1) || |
888 | !check_bytes_and_report(s, page, p, "Poison" , |
889 | p + s->object_size - 1, POISON_END, 1))) |
890 | return 0; |
891 | /* |
892 | * check_pad_bytes cleans up on its own. |
893 | */ |
894 | check_pad_bytes(s, page, p); |
895 | } |
896 | |
897 | if (!s->offset && val == SLUB_RED_ACTIVE) |
898 | /* |
899 | * Object and freepointer overlap. Cannot check |
900 | * freepointer while object is allocated. |
901 | */ |
902 | return 1; |
903 | |
904 | /* Check free pointer validity */ |
905 | if (!check_valid_pointer(s, page, get_freepointer(s, p))) { |
906 | object_err(s, page, p, "Freepointer corrupt" ); |
907 | /* |
908 | * No choice but to zap it and thus lose the remainder |
909 | * of the free objects in this slab. May cause |
910 | * another error because the object count is now wrong. |
911 | */ |
912 | set_freepointer(s, p, NULL); |
913 | return 0; |
914 | } |
915 | return 1; |
916 | } |
917 | |
918 | static int check_slab(struct kmem_cache *s, struct page *page) |
919 | { |
920 | int maxobj; |
921 | |
922 | VM_BUG_ON(!irqs_disabled()); |
923 | |
924 | if (!PageSlab(page)) { |
925 | slab_err(s, page, "Not a valid slab page" ); |
926 | return 0; |
927 | } |
928 | |
929 | maxobj = order_objects(compound_order(page), s->size); |
930 | if (page->objects > maxobj) { |
931 | slab_err(s, page, "objects %u > max %u" , |
932 | page->objects, maxobj); |
933 | return 0; |
934 | } |
935 | if (page->inuse > page->objects) { |
936 | slab_err(s, page, "inuse %u > max %u" , |
937 | page->inuse, page->objects); |
938 | return 0; |
939 | } |
940 | /* Slab_pad_check fixes things up after itself */ |
941 | slab_pad_check(s, page); |
942 | return 1; |
943 | } |
944 | |
945 | /* |
946 | * Determine if a certain object on a page is on the freelist. Must hold the |
947 | * slab lock to guarantee that the chains are in a consistent state. |
948 | */ |
949 | static int on_freelist(struct kmem_cache *s, struct page *page, void *search) |
950 | { |
951 | int nr = 0; |
952 | void *fp; |
953 | void *object = NULL; |
954 | int max_objects; |
955 | |
956 | fp = page->freelist; |
957 | while (fp && nr <= page->objects) { |
958 | if (fp == search) |
959 | return 1; |
960 | if (!check_valid_pointer(s, page, fp)) { |
961 | if (object) { |
962 | object_err(s, page, object, |
963 | "Freechain corrupt" ); |
964 | set_freepointer(s, object, NULL); |
965 | } else { |
966 | slab_err(s, page, "Freepointer corrupt" ); |
967 | page->freelist = NULL; |
968 | page->inuse = page->objects; |
969 | slab_fix(s, "Freelist cleared" ); |
970 | return 0; |
971 | } |
972 | break; |
973 | } |
974 | object = fp; |
975 | fp = get_freepointer(s, object); |
976 | nr++; |
977 | } |
978 | |
979 | max_objects = order_objects(compound_order(page), s->size); |
980 | if (max_objects > MAX_OBJS_PER_PAGE) |
981 | max_objects = MAX_OBJS_PER_PAGE; |
982 | |
983 | if (page->objects != max_objects) { |
984 | slab_err(s, page, "Wrong number of objects. Found %d but should be %d" , |
985 | page->objects, max_objects); |
986 | page->objects = max_objects; |
987 | slab_fix(s, "Number of objects adjusted." ); |
988 | } |
989 | if (page->inuse != page->objects - nr) { |
990 | slab_err(s, page, "Wrong object count. Counter is %d but counted were %d" , |
991 | page->inuse, page->objects - nr); |
992 | page->inuse = page->objects - nr; |
993 | slab_fix(s, "Object count adjusted." ); |
994 | } |
995 | return search == NULL; |
996 | } |
997 | |
998 | static void trace(struct kmem_cache *s, struct page *page, void *object, |
999 | int alloc) |
1000 | { |
1001 | if (s->flags & SLAB_TRACE) { |
1002 | pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n" , |
1003 | s->name, |
1004 | alloc ? "alloc" : "free" , |
1005 | object, page->inuse, |
1006 | page->freelist); |
1007 | |
1008 | if (!alloc) |
1009 | print_section(KERN_INFO, "Object " , (void *)object, |
1010 | s->object_size); |
1011 | |
1012 | dump_stack(); |
1013 | } |
1014 | } |
1015 | |
1016 | /* |
1017 | * Tracking of fully allocated slabs for debugging purposes. |
1018 | */ |
1019 | static void add_full(struct kmem_cache *s, |
1020 | struct kmem_cache_node *n, struct page *page) |
1021 | { |
1022 | if (!(s->flags & SLAB_STORE_USER)) |
1023 | return; |
1024 | |
1025 | lockdep_assert_held(&n->list_lock); |
1026 | list_add(&page->lru, &n->full); |
1027 | } |
1028 | |
1029 | static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page) |
1030 | { |
1031 | if (!(s->flags & SLAB_STORE_USER)) |
1032 | return; |
1033 | |
1034 | lockdep_assert_held(&n->list_lock); |
1035 | list_del(&page->lru); |
1036 | } |
1037 | |
1038 | /* Tracking of the number of slabs for debugging purposes */ |
1039 | static inline unsigned long slabs_node(struct kmem_cache *s, int node) |
1040 | { |
1041 | struct kmem_cache_node *n = get_node(s, node); |
1042 | |
1043 | return atomic_long_read(&n->nr_slabs); |
1044 | } |
1045 | |
1046 | static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) |
1047 | { |
1048 | return atomic_long_read(&n->nr_slabs); |
1049 | } |
1050 | |
1051 | static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) |
1052 | { |
1053 | struct kmem_cache_node *n = get_node(s, node); |
1054 | |
1055 | /* |
1056 | * May be called early in order to allocate a slab for the |
1057 | * kmem_cache_node structure. Solve the chicken-egg |
1058 | * dilemma by deferring the increment of the count during |
1059 | * bootstrap (see early_kmem_cache_node_alloc). |
1060 | */ |
1061 | if (likely(n)) { |
1062 | atomic_long_inc(&n->nr_slabs); |
1063 | atomic_long_add(objects, &n->total_objects); |
1064 | } |
1065 | } |
1066 | static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) |
1067 | { |
1068 | struct kmem_cache_node *n = get_node(s, node); |
1069 | |
1070 | atomic_long_dec(&n->nr_slabs); |
1071 | atomic_long_sub(objects, &n->total_objects); |
1072 | } |
1073 | |
1074 | /* Object debug checks for alloc/free paths */ |
1075 | static void setup_object_debug(struct kmem_cache *s, struct page *page, |
1076 | void *object) |
1077 | { |
1078 | if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))) |
1079 | return; |
1080 | |
1081 | init_object(s, object, SLUB_RED_INACTIVE); |
1082 | init_tracking(s, object); |
1083 | } |
1084 | |
1085 | static void setup_page_debug(struct kmem_cache *s, void *addr, int order) |
1086 | { |
1087 | if (!(s->flags & SLAB_POISON)) |
1088 | return; |
1089 | |
1090 | metadata_access_enable(); |
1091 | memset(addr, POISON_INUSE, PAGE_SIZE << order); |
1092 | metadata_access_disable(); |
1093 | } |
1094 | |
1095 | static inline int alloc_consistency_checks(struct kmem_cache *s, |
1096 | struct page *page, void *object) |
1097 | { |
1098 | if (!check_slab(s, page)) |
1099 | return 0; |
1100 | |
1101 | if (!check_valid_pointer(s, page, object)) { |
1102 | object_err(s, page, object, "Freelist Pointer check fails" ); |
1103 | return 0; |
1104 | } |
1105 | |
1106 | if (!check_object(s, page, object, SLUB_RED_INACTIVE)) |
1107 | return 0; |
1108 | |
1109 | return 1; |
1110 | } |
1111 | |
1112 | static noinline int alloc_debug_processing(struct kmem_cache *s, |
1113 | struct page *page, |
1114 | void *object, unsigned long addr) |
1115 | { |
1116 | if (s->flags & SLAB_CONSISTENCY_CHECKS) { |
1117 | if (!alloc_consistency_checks(s, page, object)) |
1118 | goto bad; |
1119 | } |
1120 | |
1121 | /* Success perform special debug activities for allocs */ |
1122 | if (s->flags & SLAB_STORE_USER) |
1123 | set_track(s, object, TRACK_ALLOC, addr); |
1124 | trace(s, page, object, 1); |
1125 | init_object(s, object, SLUB_RED_ACTIVE); |
1126 | return 1; |
1127 | |
1128 | bad: |
1129 | if (PageSlab(page)) { |
1130 | /* |
1131 | * If this is a slab page then lets do the best we can |
1132 | * to avoid issues in the future. Marking all objects |
1133 | * as used avoids touching the remaining objects. |
1134 | */ |
1135 | slab_fix(s, "Marking all objects used" ); |
1136 | page->inuse = page->objects; |
1137 | page->freelist = NULL; |
1138 | } |
1139 | return 0; |
1140 | } |
1141 | |
1142 | static inline int free_consistency_checks(struct kmem_cache *s, |
1143 | struct page *page, void *object, unsigned long addr) |
1144 | { |
1145 | if (!check_valid_pointer(s, page, object)) { |
1146 | slab_err(s, page, "Invalid object pointer 0x%p" , object); |
1147 | return 0; |
1148 | } |
1149 | |
1150 | if (on_freelist(s, page, object)) { |
1151 | object_err(s, page, object, "Object already free" ); |
1152 | return 0; |
1153 | } |
1154 | |
1155 | if (!check_object(s, page, object, SLUB_RED_ACTIVE)) |
1156 | return 0; |
1157 | |
1158 | if (unlikely(s != page->slab_cache)) { |
1159 | if (!PageSlab(page)) { |
1160 | slab_err(s, page, "Attempt to free object(0x%p) outside of slab" , |
1161 | object); |
1162 | } else if (!page->slab_cache) { |
1163 | pr_err("SLUB <none>: no slab for object 0x%p.\n" , |
1164 | object); |
1165 | dump_stack(); |
1166 | } else |
1167 | object_err(s, page, object, |
1168 | "page slab pointer corrupt." ); |
1169 | return 0; |
1170 | } |
1171 | return 1; |
1172 | } |
1173 | |
1174 | /* Supports checking bulk free of a constructed freelist */ |
1175 | static noinline int free_debug_processing( |
1176 | struct kmem_cache *s, struct page *page, |
1177 | void *head, void *tail, int bulk_cnt, |
1178 | unsigned long addr) |
1179 | { |
1180 | struct kmem_cache_node *n = get_node(s, page_to_nid(page)); |
1181 | void *object = head; |
1182 | int cnt = 0; |
1183 | unsigned long uninitialized_var(flags); |
1184 | int ret = 0; |
1185 | |
1186 | spin_lock_irqsave(&n->list_lock, flags); |
1187 | slab_lock(page); |
1188 | |
1189 | if (s->flags & SLAB_CONSISTENCY_CHECKS) { |
1190 | if (!check_slab(s, page)) |
1191 | goto out; |
1192 | } |
1193 | |
1194 | next_object: |
1195 | cnt++; |
1196 | |
1197 | if (s->flags & SLAB_CONSISTENCY_CHECKS) { |
1198 | if (!free_consistency_checks(s, page, object, addr)) |
1199 | goto out; |
1200 | } |
1201 | |
1202 | if (s->flags & SLAB_STORE_USER) |
1203 | set_track(s, object, TRACK_FREE, addr); |
1204 | trace(s, page, object, 0); |
1205 | /* Freepointer not overwritten by init_object(), SLAB_POISON moved it */ |
1206 | init_object(s, object, SLUB_RED_INACTIVE); |
1207 | |
1208 | /* Reached end of constructed freelist yet? */ |
1209 | if (object != tail) { |
1210 | object = get_freepointer(s, object); |
1211 | goto next_object; |
1212 | } |
1213 | ret = 1; |
1214 | |
1215 | out: |
1216 | if (cnt != bulk_cnt) |
1217 | slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n" , |
1218 | bulk_cnt, cnt); |
1219 | |
1220 | slab_unlock(page); |
1221 | spin_unlock_irqrestore(&n->list_lock, flags); |
1222 | if (!ret) |
1223 | slab_fix(s, "Object at 0x%p not freed" , object); |
1224 | return ret; |
1225 | } |
1226 | |
1227 | static int __init setup_slub_debug(char *str) |
1228 | { |
1229 | slub_debug = DEBUG_DEFAULT_FLAGS; |
1230 | if (*str++ != '=' || !*str) |
1231 | /* |
1232 | * No options specified. Switch on full debugging. |
1233 | */ |
1234 | goto out; |
1235 | |
1236 | if (*str == ',') |
1237 | /* |
1238 | * No options but restriction on slabs. This means full |
1239 | * debugging for slabs matching a pattern. |
1240 | */ |
1241 | goto check_slabs; |
1242 | |
1243 | slub_debug = 0; |
1244 | if (*str == '-') |
1245 | /* |
1246 | * Switch off all debugging measures. |
1247 | */ |
1248 | goto out; |
1249 | |
1250 | /* |
1251 | * Determine which debug features should be switched on |
1252 | */ |
1253 | for (; *str && *str != ','; str++) { |
1254 | switch (tolower(*str)) { |
1255 | case 'f': |
1256 | slub_debug |= SLAB_CONSISTENCY_CHECKS; |
1257 | break; |
1258 | case 'z': |
1259 | slub_debug |= SLAB_RED_ZONE; |
1260 | break; |
1261 | case 'p': |
1262 | slub_debug |= SLAB_POISON; |
1263 | break; |
1264 | case 'u': |
1265 | slub_debug |= SLAB_STORE_USER; |
1266 | break; |
1267 | case 't': |
1268 | slub_debug |= SLAB_TRACE; |
1269 | break; |
1270 | case 'a': |
1271 | slub_debug |= SLAB_FAILSLAB; |
1272 | break; |
1273 | case 'o': |
1274 | /* |
1275 | * Avoid enabling debugging on caches if its minimum |
1276 | * order would increase as a result. |
1277 | */ |
1278 | disable_higher_order_debug = 1; |
1279 | break; |
1280 | default: |
1281 | pr_err("slub_debug option '%c' unknown. skipped\n" , |
1282 | *str); |
1283 | } |
1284 | } |
1285 | |
1286 | check_slabs: |
1287 | if (*str == ',') |
1288 | slub_debug_slabs = str + 1; |
1289 | out: |
1290 | return 1; |
1291 | } |
1292 | |
1293 | __setup("slub_debug" , setup_slub_debug); |
1294 | |
1295 | /* |
1296 | * kmem_cache_flags - apply debugging options to the cache |
1297 | * @object_size: the size of an object without meta data |
1298 | * @flags: flags to set |
1299 | * @name: name of the cache |
1300 | * @ctor: constructor function |
1301 | * |
1302 | * Debug option(s) are applied to @flags. In addition to the debug |
1303 | * option(s), if a slab name (or multiple) is specified i.e. |
1304 | * slub_debug=<Debug-Options>,<slab name1>,<slab name2> ... |
1305 | * then only the select slabs will receive the debug option(s). |
1306 | */ |
1307 | slab_flags_t kmem_cache_flags(unsigned int object_size, |
1308 | slab_flags_t flags, const char *name, |
1309 | void (*ctor)(void *)) |
1310 | { |
1311 | char *iter; |
1312 | size_t len; |
1313 | |
1314 | /* If slub_debug = 0, it folds into the if conditional. */ |
1315 | if (!slub_debug_slabs) |
1316 | return flags | slub_debug; |
1317 | |
1318 | len = strlen(name); |
1319 | iter = slub_debug_slabs; |
1320 | while (*iter) { |
1321 | char *end, *glob; |
1322 | size_t cmplen; |
1323 | |
1324 | end = strchr(iter, ','); |
1325 | if (!end) |
1326 | end = iter + strlen(iter); |
1327 | |
1328 | glob = strnchr(iter, end - iter, '*'); |
1329 | if (glob) |
1330 | cmplen = glob - iter; |
1331 | else |
1332 | cmplen = max_t(size_t, len, (end - iter)); |
1333 | |
1334 | if (!strncmp(name, iter, cmplen)) { |
1335 | flags |= slub_debug; |
1336 | break; |
1337 | } |
1338 | |
1339 | if (!*end) |
1340 | break; |
1341 | iter = end + 1; |
1342 | } |
1343 | |
1344 | return flags; |
1345 | } |
1346 | #else /* !CONFIG_SLUB_DEBUG */ |
1347 | static inline void setup_object_debug(struct kmem_cache *s, |
1348 | struct page *page, void *object) {} |
1349 | static inline void setup_page_debug(struct kmem_cache *s, |
1350 | void *addr, int order) {} |
1351 | |
1352 | static inline int alloc_debug_processing(struct kmem_cache *s, |
1353 | struct page *page, void *object, unsigned long addr) { return 0; } |
1354 | |
1355 | static inline int free_debug_processing( |
1356 | struct kmem_cache *s, struct page *page, |
1357 | void *head, void *tail, int bulk_cnt, |
1358 | unsigned long addr) { return 0; } |
1359 | |
1360 | static inline int slab_pad_check(struct kmem_cache *s, struct page *page) |
1361 | { return 1; } |
1362 | static inline int check_object(struct kmem_cache *s, struct page *page, |
1363 | void *object, u8 val) { return 1; } |
1364 | static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n, |
1365 | struct page *page) {} |
1366 | static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, |
1367 | struct page *page) {} |
1368 | slab_flags_t kmem_cache_flags(unsigned int object_size, |
1369 | slab_flags_t flags, const char *name, |
1370 | void (*ctor)(void *)) |
1371 | { |
1372 | return flags; |
1373 | } |
1374 | #define slub_debug 0 |
1375 | |
1376 | #define disable_higher_order_debug 0 |
1377 | |
1378 | static inline unsigned long slabs_node(struct kmem_cache *s, int node) |
1379 | { return 0; } |
1380 | static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) |
1381 | { return 0; } |
1382 | static inline void inc_slabs_node(struct kmem_cache *s, int node, |
1383 | int objects) {} |
1384 | static inline void dec_slabs_node(struct kmem_cache *s, int node, |
1385 | int objects) {} |
1386 | |
1387 | #endif /* CONFIG_SLUB_DEBUG */ |
1388 | |
1389 | /* |
1390 | * Hooks for other subsystems that check memory allocations. In a typical |
1391 | * production configuration these hooks all should produce no code at all. |
1392 | */ |
1393 | static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags) |
1394 | { |
1395 | ptr = kasan_kmalloc_large(ptr, size, flags); |
1396 | /* As ptr might get tagged, call kmemleak hook after KASAN. */ |
1397 | kmemleak_alloc(ptr, size, 1, flags); |
1398 | return ptr; |
1399 | } |
1400 | |
1401 | static __always_inline void kfree_hook(void *x) |
1402 | { |
1403 | kmemleak_free(x); |
1404 | kasan_kfree_large(x, _RET_IP_); |
1405 | } |
1406 | |
1407 | static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x) |
1408 | { |
1409 | kmemleak_free_recursive(x, s->flags); |
1410 | |
1411 | /* |
1412 | * Trouble is that we may no longer disable interrupts in the fast path |
1413 | * So in order to make the debug calls that expect irqs to be |
1414 | * disabled we need to disable interrupts temporarily. |
1415 | */ |
1416 | #ifdef CONFIG_LOCKDEP |
1417 | { |
1418 | unsigned long flags; |
1419 | |
1420 | local_irq_save(flags); |
1421 | debug_check_no_locks_freed(x, s->object_size); |
1422 | local_irq_restore(flags); |
1423 | } |
1424 | #endif |
1425 | if (!(s->flags & SLAB_DEBUG_OBJECTS)) |
1426 | debug_check_no_obj_freed(x, s->object_size); |
1427 | |
1428 | /* KASAN might put x into memory quarantine, delaying its reuse */ |
1429 | return kasan_slab_free(s, x, _RET_IP_); |
1430 | } |
1431 | |
1432 | static inline bool slab_free_freelist_hook(struct kmem_cache *s, |
1433 | void **head, void **tail) |
1434 | { |
1435 | /* |
1436 | * Compiler cannot detect this function can be removed if slab_free_hook() |
1437 | * evaluates to nothing. Thus, catch all relevant config debug options here. |
1438 | */ |
1439 | #if defined(CONFIG_LOCKDEP) || \ |
1440 | defined(CONFIG_DEBUG_KMEMLEAK) || \ |
1441 | defined(CONFIG_DEBUG_OBJECTS_FREE) || \ |
1442 | defined(CONFIG_KASAN) |
1443 | |
1444 | void *object; |
1445 | void *next = *head; |
1446 | void *old_tail = *tail ? *tail : *head; |
1447 | |
1448 | /* Head and tail of the reconstructed freelist */ |
1449 | *head = NULL; |
1450 | *tail = NULL; |
1451 | |
1452 | do { |
1453 | object = next; |
1454 | next = get_freepointer(s, object); |
1455 | /* If object's reuse doesn't have to be delayed */ |
1456 | if (!slab_free_hook(s, object)) { |
1457 | /* Move object to the new freelist */ |
1458 | set_freepointer(s, object, *head); |
1459 | *head = object; |
1460 | if (!*tail) |
1461 | *tail = object; |
1462 | } |
1463 | } while (object != old_tail); |
1464 | |
1465 | if (*head == *tail) |
1466 | *tail = NULL; |
1467 | |
1468 | return *head != NULL; |
1469 | #else |
1470 | return true; |
1471 | #endif |
1472 | } |
1473 | |
1474 | static void *setup_object(struct kmem_cache *s, struct page *page, |
1475 | void *object) |
1476 | { |
1477 | setup_object_debug(s, page, object); |
1478 | object = kasan_init_slab_obj(s, object); |
1479 | if (unlikely(s->ctor)) { |
1480 | kasan_unpoison_object_data(s, object); |
1481 | s->ctor(object); |
1482 | kasan_poison_object_data(s, object); |
1483 | } |
1484 | return object; |
1485 | } |
1486 | |
1487 | /* |
1488 | * Slab allocation and freeing |
1489 | */ |
1490 | static inline struct page *alloc_slab_page(struct kmem_cache *s, |
1491 | gfp_t flags, int node, struct kmem_cache_order_objects oo) |
1492 | { |
1493 | struct page *page; |
1494 | unsigned int order = oo_order(oo); |
1495 | |
1496 | if (node == NUMA_NO_NODE) |
1497 | page = alloc_pages(flags, order); |
1498 | else |
1499 | page = __alloc_pages_node(node, flags, order); |
1500 | |
1501 | if (page && memcg_charge_slab(page, flags, order, s)) { |
1502 | __free_pages(page, order); |
1503 | page = NULL; |
1504 | } |
1505 | |
1506 | return page; |
1507 | } |
1508 | |
1509 | #ifdef CONFIG_SLAB_FREELIST_RANDOM |
1510 | /* Pre-initialize the random sequence cache */ |
1511 | static int init_cache_random_seq(struct kmem_cache *s) |
1512 | { |
1513 | unsigned int count = oo_objects(s->oo); |
1514 | int err; |
1515 | |
1516 | /* Bailout if already initialised */ |
1517 | if (s->random_seq) |
1518 | return 0; |
1519 | |
1520 | err = cache_random_seq_create(s, count, GFP_KERNEL); |
1521 | if (err) { |
1522 | pr_err("SLUB: Unable to initialize free list for %s\n" , |
1523 | s->name); |
1524 | return err; |
1525 | } |
1526 | |
1527 | /* Transform to an offset on the set of pages */ |
1528 | if (s->random_seq) { |
1529 | unsigned int i; |
1530 | |
1531 | for (i = 0; i < count; i++) |
1532 | s->random_seq[i] *= s->size; |
1533 | } |
1534 | return 0; |
1535 | } |
1536 | |
1537 | /* Initialize each random sequence freelist per cache */ |
1538 | static void __init init_freelist_randomization(void) |
1539 | { |
1540 | struct kmem_cache *s; |
1541 | |
1542 | mutex_lock(&slab_mutex); |
1543 | |
1544 | list_for_each_entry(s, &slab_caches, list) |
1545 | init_cache_random_seq(s); |
1546 | |
1547 | mutex_unlock(&slab_mutex); |
1548 | } |
1549 | |
1550 | /* Get the next entry on the pre-computed freelist randomized */ |
1551 | static void *next_freelist_entry(struct kmem_cache *s, struct page *page, |
1552 | unsigned long *pos, void *start, |
1553 | unsigned long page_limit, |
1554 | unsigned long freelist_count) |
1555 | { |
1556 | unsigned int idx; |
1557 | |
1558 | /* |
1559 | * If the target page allocation failed, the number of objects on the |
1560 | * page might be smaller than the usual size defined by the cache. |
1561 | */ |
1562 | do { |
1563 | idx = s->random_seq[*pos]; |
1564 | *pos += 1; |
1565 | if (*pos >= freelist_count) |
1566 | *pos = 0; |
1567 | } while (unlikely(idx >= page_limit)); |
1568 | |
1569 | return (char *)start + idx; |
1570 | } |
1571 | |
1572 | /* Shuffle the single linked freelist based on a random pre-computed sequence */ |
1573 | static bool shuffle_freelist(struct kmem_cache *s, struct page *page) |
1574 | { |
1575 | void *start; |
1576 | void *cur; |
1577 | void *next; |
1578 | unsigned long idx, pos, page_limit, freelist_count; |
1579 | |
1580 | if (page->objects < 2 || !s->random_seq) |
1581 | return false; |
1582 | |
1583 | freelist_count = oo_objects(s->oo); |
1584 | pos = get_random_int() % freelist_count; |
1585 | |
1586 | page_limit = page->objects * s->size; |
1587 | start = fixup_red_left(s, page_address(page)); |
1588 | |
1589 | /* First entry is used as the base of the freelist */ |
1590 | cur = next_freelist_entry(s, page, &pos, start, page_limit, |
1591 | freelist_count); |
1592 | cur = setup_object(s, page, cur); |
1593 | page->freelist = cur; |
1594 | |
1595 | for (idx = 1; idx < page->objects; idx++) { |
1596 | next = next_freelist_entry(s, page, &pos, start, page_limit, |
1597 | freelist_count); |
1598 | next = setup_object(s, page, next); |
1599 | set_freepointer(s, cur, next); |
1600 | cur = next; |
1601 | } |
1602 | set_freepointer(s, cur, NULL); |
1603 | |
1604 | return true; |
1605 | } |
1606 | #else |
1607 | static inline int init_cache_random_seq(struct kmem_cache *s) |
1608 | { |
1609 | return 0; |
1610 | } |
1611 | static inline void init_freelist_randomization(void) { } |
1612 | static inline bool shuffle_freelist(struct kmem_cache *s, struct page *page) |
1613 | { |
1614 | return false; |
1615 | } |
1616 | #endif /* CONFIG_SLAB_FREELIST_RANDOM */ |
1617 | |
1618 | static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) |
1619 | { |
1620 | struct page *page; |
1621 | struct kmem_cache_order_objects oo = s->oo; |
1622 | gfp_t alloc_gfp; |
1623 | void *start, *p, *next; |
1624 | int idx, order; |
1625 | bool shuffle; |
1626 | |
1627 | flags &= gfp_allowed_mask; |
1628 | |
1629 | if (gfpflags_allow_blocking(flags)) |
1630 | local_irq_enable(); |
1631 | |
1632 | flags |= s->allocflags; |
1633 | |
1634 | /* |
1635 | * Let the initial higher-order allocation fail under memory pressure |
1636 | * so we fall-back to the minimum order allocation. |
1637 | */ |
1638 | alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL; |
1639 | if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min)) |
1640 | alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL); |
1641 | |
1642 | page = alloc_slab_page(s, alloc_gfp, node, oo); |
1643 | if (unlikely(!page)) { |
1644 | oo = s->min; |
1645 | alloc_gfp = flags; |
1646 | /* |
1647 | * Allocation may have failed due to fragmentation. |
1648 | * Try a lower order alloc if possible |
1649 | */ |
1650 | page = alloc_slab_page(s, alloc_gfp, node, oo); |
1651 | if (unlikely(!page)) |
1652 | goto out; |
1653 | stat(s, ORDER_FALLBACK); |
1654 | } |
1655 | |
1656 | page->objects = oo_objects(oo); |
1657 | |
1658 | order = compound_order(page); |
1659 | page->slab_cache = s; |
1660 | __SetPageSlab(page); |
1661 | if (page_is_pfmemalloc(page)) |
1662 | SetPageSlabPfmemalloc(page); |
1663 | |
1664 | kasan_poison_slab(page); |
1665 | |
1666 | start = page_address(page); |
1667 | |
1668 | setup_page_debug(s, start, order); |
1669 | |
1670 | shuffle = shuffle_freelist(s, page); |
1671 | |
1672 | if (!shuffle) { |
1673 | start = fixup_red_left(s, start); |
1674 | start = setup_object(s, page, start); |
1675 | page->freelist = start; |
1676 | for (idx = 0, p = start; idx < page->objects - 1; idx++) { |
1677 | next = p + s->size; |
1678 | next = setup_object(s, page, next); |
1679 | set_freepointer(s, p, next); |
1680 | p = next; |
1681 | } |
1682 | set_freepointer(s, p, NULL); |
1683 | } |
1684 | |
1685 | page->inuse = page->objects; |
1686 | page->frozen = 1; |
1687 | |
1688 | out: |
1689 | if (gfpflags_allow_blocking(flags)) |
1690 | local_irq_disable(); |
1691 | if (!page) |
1692 | return NULL; |
1693 | |
1694 | mod_lruvec_page_state(page, |
1695 | (s->flags & SLAB_RECLAIM_ACCOUNT) ? |
1696 | NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE, |
1697 | 1 << oo_order(oo)); |
1698 | |
1699 | inc_slabs_node(s, page_to_nid(page), page->objects); |
1700 | |
1701 | return page; |
1702 | } |
1703 | |
1704 | static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) |
1705 | { |
1706 | if (unlikely(flags & GFP_SLAB_BUG_MASK)) { |
1707 | gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; |
1708 | flags &= ~GFP_SLAB_BUG_MASK; |
1709 | pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n" , |
1710 | invalid_mask, &invalid_mask, flags, &flags); |
1711 | dump_stack(); |
1712 | } |
1713 | |
1714 | return allocate_slab(s, |
1715 | flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node); |
1716 | } |
1717 | |
1718 | static void __free_slab(struct kmem_cache *s, struct page *page) |
1719 | { |
1720 | int order = compound_order(page); |
1721 | int pages = 1 << order; |
1722 | |
1723 | if (s->flags & SLAB_CONSISTENCY_CHECKS) { |
1724 | void *p; |
1725 | |
1726 | slab_pad_check(s, page); |
1727 | for_each_object(p, s, page_address(page), |
1728 | page->objects) |
1729 | check_object(s, page, p, SLUB_RED_INACTIVE); |
1730 | } |
1731 | |
1732 | mod_lruvec_page_state(page, |
1733 | (s->flags & SLAB_RECLAIM_ACCOUNT) ? |
1734 | NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE, |
1735 | -pages); |
1736 | |
1737 | __ClearPageSlabPfmemalloc(page); |
1738 | __ClearPageSlab(page); |
1739 | |
1740 | page->mapping = NULL; |
1741 | if (current->reclaim_state) |
1742 | current->reclaim_state->reclaimed_slab += pages; |
1743 | memcg_uncharge_slab(page, order, s); |
1744 | __free_pages(page, order); |
1745 | } |
1746 | |
1747 | static void rcu_free_slab(struct rcu_head *h) |
1748 | { |
1749 | struct page *page = container_of(h, struct page, rcu_head); |
1750 | |
1751 | __free_slab(page->slab_cache, page); |
1752 | } |
1753 | |
1754 | static void free_slab(struct kmem_cache *s, struct page *page) |
1755 | { |
1756 | if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) { |
1757 | call_rcu(&page->rcu_head, rcu_free_slab); |
1758 | } else |
1759 | __free_slab(s, page); |
1760 | } |
1761 | |
1762 | static void discard_slab(struct kmem_cache *s, struct page *page) |
1763 | { |
1764 | dec_slabs_node(s, page_to_nid(page), page->objects); |
1765 | free_slab(s, page); |
1766 | } |
1767 | |
1768 | /* |
1769 | * Management of partially allocated slabs. |
1770 | */ |
1771 | static inline void |
1772 | __add_partial(struct kmem_cache_node *n, struct page *page, int tail) |
1773 | { |
1774 | n->nr_partial++; |
1775 | if (tail == DEACTIVATE_TO_TAIL) |
1776 | list_add_tail(&page->lru, &n->partial); |
1777 | else |
1778 | list_add(&page->lru, &n->partial); |
1779 | } |
1780 | |
1781 | static inline void add_partial(struct kmem_cache_node *n, |
1782 | struct page *page, int tail) |
1783 | { |
1784 | lockdep_assert_held(&n->list_lock); |
1785 | __add_partial(n, page, tail); |
1786 | } |
1787 | |
1788 | static inline void remove_partial(struct kmem_cache_node *n, |
1789 | struct page *page) |
1790 | { |
1791 | lockdep_assert_held(&n->list_lock); |
1792 | list_del(&page->lru); |
1793 | n->nr_partial--; |
1794 | } |
1795 | |
1796 | /* |
1797 | * Remove slab from the partial list, freeze it and |
1798 | * return the pointer to the freelist. |
1799 | * |
1800 | * Returns a list of objects or NULL if it fails. |
1801 | */ |
1802 | static inline void *acquire_slab(struct kmem_cache *s, |
1803 | struct kmem_cache_node *n, struct page *page, |
1804 | int mode, int *objects) |
1805 | { |
1806 | void *freelist; |
1807 | unsigned long counters; |
1808 | struct page new; |
1809 | |
1810 | lockdep_assert_held(&n->list_lock); |
1811 | |
1812 | /* |
1813 | * Zap the freelist and set the frozen bit. |
1814 | * The old freelist is the list of objects for the |
1815 | * per cpu allocation list. |
1816 | */ |
1817 | freelist = page->freelist; |
1818 | counters = page->counters; |
1819 | new.counters = counters; |
1820 | *objects = new.objects - new.inuse; |
1821 | if (mode) { |
1822 | new.inuse = page->objects; |
1823 | new.freelist = NULL; |
1824 | } else { |
1825 | new.freelist = freelist; |
1826 | } |
1827 | |
1828 | VM_BUG_ON(new.frozen); |
1829 | new.frozen = 1; |
1830 | |
1831 | if (!__cmpxchg_double_slab(s, page, |
1832 | freelist, counters, |
1833 | new.freelist, new.counters, |
1834 | "acquire_slab" )) |
1835 | return NULL; |
1836 | |
1837 | remove_partial(n, page); |
1838 | WARN_ON(!freelist); |
1839 | return freelist; |
1840 | } |
1841 | |
1842 | static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); |
1843 | static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); |
1844 | |
1845 | /* |
1846 | * Try to allocate a partial slab from a specific node. |
1847 | */ |
1848 | static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, |
1849 | struct kmem_cache_cpu *c, gfp_t flags) |
1850 | { |
1851 | struct page *page, *page2; |
1852 | void *object = NULL; |
1853 | unsigned int available = 0; |
1854 | int objects; |
1855 | |
1856 | /* |
1857 | * Racy check. If we mistakenly see no partial slabs then we |
1858 | * just allocate an empty slab. If we mistakenly try to get a |
1859 | * partial slab and there is none available then get_partials() |
1860 | * will return NULL. |
1861 | */ |
1862 | if (!n || !n->nr_partial) |
1863 | return NULL; |
1864 | |
1865 | spin_lock(&n->list_lock); |
1866 | list_for_each_entry_safe(page, page2, &n->partial, lru) { |
1867 | void *t; |
1868 | |
1869 | if (!pfmemalloc_match(page, flags)) |
1870 | continue; |
1871 | |
1872 | t = acquire_slab(s, n, page, object == NULL, &objects); |
1873 | if (!t) |
1874 | break; |
1875 | |
1876 | available += objects; |
1877 | if (!object) { |
1878 | c->page = page; |
1879 | stat(s, ALLOC_FROM_PARTIAL); |
1880 | object = t; |
1881 | } else { |
1882 | put_cpu_partial(s, page, 0); |
1883 | stat(s, CPU_PARTIAL_NODE); |
1884 | } |
1885 | if (!kmem_cache_has_cpu_partial(s) |
1886 | || available > slub_cpu_partial(s) / 2) |
1887 | break; |
1888 | |
1889 | } |
1890 | spin_unlock(&n->list_lock); |
1891 | return object; |
1892 | } |
1893 | |
1894 | /* |
1895 | * Get a page from somewhere. Search in increasing NUMA distances. |
1896 | */ |
1897 | static void *get_any_partial(struct kmem_cache *s, gfp_t flags, |
1898 | struct kmem_cache_cpu *c) |
1899 | { |
1900 | #ifdef CONFIG_NUMA |
1901 | struct zonelist *zonelist; |
1902 | struct zoneref *z; |
1903 | struct zone *zone; |
1904 | enum zone_type high_zoneidx = gfp_zone(flags); |
1905 | void *object; |
1906 | unsigned int cpuset_mems_cookie; |
1907 | |
1908 | /* |
1909 | * The defrag ratio allows a configuration of the tradeoffs between |
1910 | * inter node defragmentation and node local allocations. A lower |
1911 | * defrag_ratio increases the tendency to do local allocations |
1912 | * instead of attempting to obtain partial slabs from other nodes. |
1913 | * |
1914 | * If the defrag_ratio is set to 0 then kmalloc() always |
1915 | * returns node local objects. If the ratio is higher then kmalloc() |
1916 | * may return off node objects because partial slabs are obtained |
1917 | * from other nodes and filled up. |
1918 | * |
1919 | * If /sys/kernel/slab/xx/remote_node_defrag_ratio is set to 100 |
1920 | * (which makes defrag_ratio = 1000) then every (well almost) |
1921 | * allocation will first attempt to defrag slab caches on other nodes. |
1922 | * This means scanning over all nodes to look for partial slabs which |
1923 | * may be expensive if we do it every time we are trying to find a slab |
1924 | * with available objects. |
1925 | */ |
1926 | if (!s->remote_node_defrag_ratio || |
1927 | get_cycles() % 1024 > s->remote_node_defrag_ratio) |
1928 | return NULL; |
1929 | |
1930 | do { |
1931 | cpuset_mems_cookie = read_mems_allowed_begin(); |
1932 | zonelist = node_zonelist(mempolicy_slab_node(), flags); |
1933 | for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { |
1934 | struct kmem_cache_node *n; |
1935 | |
1936 | n = get_node(s, zone_to_nid(zone)); |
1937 | |
1938 | if (n && cpuset_zone_allowed(zone, flags) && |
1939 | n->nr_partial > s->min_partial) { |
1940 | object = get_partial_node(s, n, c, flags); |
1941 | if (object) { |
1942 | /* |
1943 | * Don't check read_mems_allowed_retry() |
1944 | * here - if mems_allowed was updated in |
1945 | * parallel, that was a harmless race |
1946 | * between allocation and the cpuset |
1947 | * update |
1948 | */ |
1949 | return object; |
1950 | } |
1951 | } |
1952 | } |
1953 | } while (read_mems_allowed_retry(cpuset_mems_cookie)); |
1954 | #endif |
1955 | return NULL; |
1956 | } |
1957 | |
1958 | /* |
1959 | * Get a partial page, lock it and return it. |
1960 | */ |
1961 | static void *get_partial(struct kmem_cache *s, gfp_t flags, int node, |
1962 | struct kmem_cache_cpu *c) |
1963 | { |
1964 | void *object; |
1965 | int searchnode = node; |
1966 | |
1967 | if (node == NUMA_NO_NODE) |
1968 | searchnode = numa_mem_id(); |
1969 | else if (!node_present_pages(node)) |
1970 | searchnode = node_to_mem_node(node); |
1971 | |
1972 | object = get_partial_node(s, get_node(s, searchnode), c, flags); |
1973 | if (object || node != NUMA_NO_NODE) |
1974 | return object; |
1975 | |
1976 | return get_any_partial(s, flags, c); |
1977 | } |
1978 | |
1979 | #ifdef CONFIG_PREEMPT |
1980 | /* |
1981 | * Calculate the next globally unique transaction for disambiguiation |
1982 | * during cmpxchg. The transactions start with the cpu number and are then |
1983 | * incremented by CONFIG_NR_CPUS. |
1984 | */ |
1985 | #define TID_STEP roundup_pow_of_two(CONFIG_NR_CPUS) |
1986 | #else |
1987 | /* |
1988 | * No preemption supported therefore also no need to check for |
1989 | * different cpus. |
1990 | */ |
1991 | #define TID_STEP 1 |
1992 | #endif |
1993 | |
1994 | static inline unsigned long next_tid(unsigned long tid) |
1995 | { |
1996 | return tid + TID_STEP; |
1997 | } |
1998 | |
1999 | static inline unsigned int tid_to_cpu(unsigned long tid) |
2000 | { |
2001 | return tid % TID_STEP; |
2002 | } |
2003 | |
2004 | static inline unsigned long tid_to_event(unsigned long tid) |
2005 | { |
2006 | return tid / TID_STEP; |
2007 | } |
2008 | |
2009 | static inline unsigned int init_tid(int cpu) |
2010 | { |
2011 | return cpu; |
2012 | } |
2013 | |
2014 | static inline void note_cmpxchg_failure(const char *n, |
2015 | const struct kmem_cache *s, unsigned long tid) |
2016 | { |
2017 | #ifdef SLUB_DEBUG_CMPXCHG |
2018 | unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid); |
2019 | |
2020 | pr_info("%s %s: cmpxchg redo " , n, s->name); |
2021 | |
2022 | #ifdef CONFIG_PREEMPT |
2023 | if (tid_to_cpu(tid) != tid_to_cpu(actual_tid)) |
2024 | pr_warn("due to cpu change %d -> %d\n" , |
2025 | tid_to_cpu(tid), tid_to_cpu(actual_tid)); |
2026 | else |
2027 | #endif |
2028 | if (tid_to_event(tid) != tid_to_event(actual_tid)) |
2029 | pr_warn("due to cpu running other code. Event %ld->%ld\n" , |
2030 | tid_to_event(tid), tid_to_event(actual_tid)); |
2031 | else |
2032 | pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n" , |
2033 | actual_tid, tid, next_tid(tid)); |
2034 | #endif |
2035 | stat(s, CMPXCHG_DOUBLE_CPU_FAIL); |
2036 | } |
2037 | |
2038 | static void init_kmem_cache_cpus(struct kmem_cache *s) |
2039 | { |
2040 | int cpu; |
2041 | |
2042 | for_each_possible_cpu(cpu) |
2043 | per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu); |
2044 | } |
2045 | |
2046 | /* |
2047 | * Remove the cpu slab |
2048 | */ |
2049 | static void deactivate_slab(struct kmem_cache *s, struct page *page, |
2050 | void *freelist, struct kmem_cache_cpu *c) |
2051 | { |
2052 | enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE }; |
2053 | struct kmem_cache_node *n = get_node(s, page_to_nid(page)); |
2054 | int lock = 0; |
2055 | enum slab_modes l = M_NONE, m = M_NONE; |
2056 | void *nextfree; |
2057 | int tail = DEACTIVATE_TO_HEAD; |
2058 | struct page new; |
2059 | struct page old; |
2060 | |
2061 | if (page->freelist) { |
2062 | stat(s, DEACTIVATE_REMOTE_FREES); |
2063 | tail = DEACTIVATE_TO_TAIL; |
2064 | } |
2065 | |
2066 | /* |
2067 | * Stage one: Free all available per cpu objects back |
2068 | * to the page freelist while it is still frozen. Leave the |
2069 | * last one. |
2070 | * |
2071 | * There is no need to take the list->lock because the page |
2072 | * is still frozen. |
2073 | */ |
2074 | while (freelist && (nextfree = get_freepointer(s, freelist))) { |
2075 | void *prior; |
2076 | unsigned long counters; |
2077 | |
2078 | do { |
2079 | prior = page->freelist; |
2080 | counters = page->counters; |
2081 | set_freepointer(s, freelist, prior); |
2082 | new.counters = counters; |
2083 | new.inuse--; |
2084 | VM_BUG_ON(!new.frozen); |
2085 | |
2086 | } while (!__cmpxchg_double_slab(s, page, |
2087 | prior, counters, |
2088 | freelist, new.counters, |
2089 | "drain percpu freelist" )); |
2090 | |
2091 | freelist = nextfree; |
2092 | } |
2093 | |
2094 | /* |
2095 | * Stage two: Ensure that the page is unfrozen while the |
2096 | * list presence reflects the actual number of objects |
2097 | * during unfreeze. |
2098 | * |
2099 | * We setup the list membership and then perform a cmpxchg |
2100 | * with the count. If there is a mismatch then the page |
2101 | * is not unfrozen but the page is on the wrong list. |
2102 | * |
2103 | * Then we restart the process which may have to remove |
2104 | * the page from the list that we just put it on again |
2105 | * because the number of objects in the slab may have |
2106 | * changed. |
2107 | */ |
2108 | redo: |
2109 | |
2110 | old.freelist = page->freelist; |
2111 | old.counters = page->counters; |
2112 | VM_BUG_ON(!old.frozen); |
2113 | |
2114 | /* Determine target state of the slab */ |
2115 | new.counters = old.counters; |
2116 | if (freelist) { |
2117 | new.inuse--; |
2118 | set_freepointer(s, freelist, old.freelist); |
2119 | new.freelist = freelist; |
2120 | } else |
2121 | new.freelist = old.freelist; |
2122 | |
2123 | new.frozen = 0; |
2124 | |
2125 | if (!new.inuse && n->nr_partial >= s->min_partial) |
2126 | m = M_FREE; |
2127 | else if (new.freelist) { |
2128 | m = M_PARTIAL; |
2129 | if (!lock) { |
2130 | lock = 1; |
2131 | /* |
2132 | * Taking the spinlock removes the possibility |
2133 | * that acquire_slab() will see a slab page that |
2134 | * is frozen |
2135 | */ |
2136 | spin_lock(&n->list_lock); |
2137 | } |
2138 | } else { |
2139 | m = M_FULL; |
2140 | if (kmem_cache_debug(s) && !lock) { |
2141 | lock = 1; |
2142 | /* |
2143 | * This also ensures that the scanning of full |
2144 | * slabs from diagnostic functions will not see |
2145 | * any frozen slabs. |
2146 | */ |
2147 | spin_lock(&n->list_lock); |
2148 | } |
2149 | } |
2150 | |
2151 | if (l != m) { |
2152 | if (l == M_PARTIAL) |
2153 | remove_partial(n, page); |
2154 | else if (l == M_FULL) |
2155 | remove_full(s, n, page); |
2156 | |
2157 | if (m == M_PARTIAL) |
2158 | add_partial(n, page, tail); |
2159 | else if (m == M_FULL) |
2160 | add_full(s, n, page); |
2161 | } |
2162 | |
2163 | l = m; |
2164 | if (!__cmpxchg_double_slab(s, page, |
2165 | old.freelist, old.counters, |
2166 | new.freelist, new.counters, |
2167 | "unfreezing slab" )) |
2168 | goto redo; |
2169 | |
2170 | if (lock) |
2171 | spin_unlock(&n->list_lock); |
2172 | |
2173 | if (m == M_PARTIAL) |
2174 | stat(s, tail); |
2175 | else if (m == M_FULL) |
2176 | stat(s, DEACTIVATE_FULL); |
2177 | else if (m == M_FREE) { |
2178 | stat(s, DEACTIVATE_EMPTY); |
2179 | discard_slab(s, page); |
2180 | stat(s, FREE_SLAB); |
2181 | } |
2182 | |
2183 | c->page = NULL; |
2184 | c->freelist = NULL; |
2185 | } |
2186 | |
2187 | /* |
2188 | * Unfreeze all the cpu partial slabs. |
2189 | * |
2190 | * This function must be called with interrupts disabled |
2191 | * for the cpu using c (or some other guarantee must be there |
2192 | * to guarantee no concurrent accesses). |
2193 | */ |
2194 | static void unfreeze_partials(struct kmem_cache *s, |
2195 | struct kmem_cache_cpu *c) |
2196 | { |
2197 | #ifdef CONFIG_SLUB_CPU_PARTIAL |
2198 | struct kmem_cache_node *n = NULL, *n2 = NULL; |
2199 | struct page *page, *discard_page = NULL; |
2200 | |
2201 | while ((page = c->partial)) { |
2202 | struct page new; |
2203 | struct page old; |
2204 | |
2205 | c->partial = page->next; |
2206 | |
2207 | n2 = get_node(s, page_to_nid(page)); |
2208 | if (n != n2) { |
2209 | if (n) |
2210 | spin_unlock(&n->list_lock); |
2211 | |
2212 | n = n2; |
2213 | spin_lock(&n->list_lock); |
2214 | } |
2215 | |
2216 | do { |
2217 | |
2218 | old.freelist = page->freelist; |
2219 | old.counters = page->counters; |
2220 | VM_BUG_ON(!old.frozen); |
2221 | |
2222 | new.counters = old.counters; |
2223 | new.freelist = old.freelist; |
2224 | |
2225 | new.frozen = 0; |
2226 | |
2227 | } while (!__cmpxchg_double_slab(s, page, |
2228 | old.freelist, old.counters, |
2229 | new.freelist, new.counters, |
2230 | "unfreezing slab" )); |
2231 | |
2232 | if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) { |
2233 | page->next = discard_page; |
2234 | discard_page = page; |
2235 | } else { |
2236 | add_partial(n, page, DEACTIVATE_TO_TAIL); |
2237 | stat(s, FREE_ADD_PARTIAL); |
2238 | } |
2239 | } |
2240 | |
2241 | if (n) |
2242 | spin_unlock(&n->list_lock); |
2243 | |
2244 | while (discard_page) { |
2245 | page = discard_page; |
2246 | discard_page = discard_page->next; |
2247 | |
2248 | stat(s, DEACTIVATE_EMPTY); |
2249 | discard_slab(s, page); |
2250 | stat(s, FREE_SLAB); |
2251 | } |
2252 | #endif |
2253 | } |
2254 | |
2255 | /* |
2256 | * Put a page that was just frozen (in __slab_free|get_partial_node) into a |
2257 | * partial page slot if available. |
2258 | * |
2259 | * If we did not find a slot then simply move all the partials to the |
2260 | * per node partial list. |
2261 | */ |
2262 | static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain) |
2263 | { |
2264 | #ifdef CONFIG_SLUB_CPU_PARTIAL |
2265 | struct page *oldpage; |
2266 | int pages; |
2267 | int pobjects; |
2268 | |
2269 | preempt_disable(); |
2270 | do { |
2271 | pages = 0; |
2272 | pobjects = 0; |
2273 | oldpage = this_cpu_read(s->cpu_slab->partial); |
2274 | |
2275 | if (oldpage) { |
2276 | pobjects = oldpage->pobjects; |
2277 | pages = oldpage->pages; |
2278 | if (drain && pobjects > s->cpu_partial) { |
2279 | unsigned long flags; |
2280 | /* |
2281 | * partial array is full. Move the existing |
2282 | * set to the per node partial list. |
2283 | */ |
2284 | local_irq_save(flags); |
2285 | unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); |
2286 | local_irq_restore(flags); |
2287 | oldpage = NULL; |
2288 | pobjects = 0; |
2289 | pages = 0; |
2290 | stat(s, CPU_PARTIAL_DRAIN); |
2291 | } |
2292 | } |
2293 | |
2294 | pages++; |
2295 | pobjects += page->objects - page->inuse; |
2296 | |
2297 | page->pages = pages; |
2298 | page->pobjects = pobjects; |
2299 | page->next = oldpage; |
2300 | |
2301 | } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) |
2302 | != oldpage); |
2303 | if (unlikely(!s->cpu_partial)) { |
2304 | unsigned long flags; |
2305 | |
2306 | local_irq_save(flags); |
2307 | unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); |
2308 | local_irq_restore(flags); |
2309 | } |
2310 | preempt_enable(); |
2311 | #endif |
2312 | } |
2313 | |
2314 | static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) |
2315 | { |
2316 | stat(s, CPUSLAB_FLUSH); |
2317 | deactivate_slab(s, c->page, c->freelist, c); |
2318 | |
2319 | c->tid = next_tid(c->tid); |
2320 | } |
2321 | |
2322 | /* |
2323 | * Flush cpu slab. |
2324 | * |
2325 | * Called from IPI handler with interrupts disabled. |
2326 | */ |
2327 | static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) |
2328 | { |
2329 | struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); |
2330 | |
2331 | if (c->page) |
2332 | flush_slab(s, c); |
2333 | |
2334 | unfreeze_partials(s, c); |
2335 | } |
2336 | |
2337 | static void flush_cpu_slab(void *d) |
2338 | { |
2339 | struct kmem_cache *s = d; |
2340 | |
2341 | __flush_cpu_slab(s, smp_processor_id()); |
2342 | } |
2343 | |
2344 | static bool has_cpu_slab(int cpu, void *info) |
2345 | { |
2346 | struct kmem_cache *s = info; |
2347 | struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); |
2348 | |
2349 | return c->page || slub_percpu_partial(c); |
2350 | } |
2351 | |
2352 | static void flush_all(struct kmem_cache *s) |
2353 | { |
2354 | on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC); |
2355 | } |
2356 | |
2357 | /* |
2358 | * Use the cpu notifier to insure that the cpu slabs are flushed when |
2359 | * necessary. |
2360 | */ |
2361 | static int slub_cpu_dead(unsigned int cpu) |
2362 | { |
2363 | struct kmem_cache *s; |
2364 | unsigned long flags; |
2365 | |
2366 | mutex_lock(&slab_mutex); |
2367 | list_for_each_entry(s, &slab_caches, list) { |
2368 | local_irq_save(flags); |
2369 | __flush_cpu_slab(s, cpu); |
2370 | local_irq_restore(flags); |
2371 | } |
2372 | mutex_unlock(&slab_mutex); |
2373 | return 0; |
2374 | } |
2375 | |
2376 | /* |
2377 | * Check if the objects in a per cpu structure fit numa |
2378 | * locality expectations. |
2379 | */ |
2380 | static inline int node_match(struct page *page, int node) |
2381 | { |
2382 | #ifdef CONFIG_NUMA |
2383 | if (node != NUMA_NO_NODE && page_to_nid(page) != node) |
2384 | return 0; |
2385 | #endif |
2386 | return 1; |
2387 | } |
2388 | |
2389 | #ifdef CONFIG_SLUB_DEBUG |
2390 | static int count_free(struct page *page) |
2391 | { |
2392 | return page->objects - page->inuse; |
2393 | } |
2394 | |
2395 | static inline unsigned long node_nr_objs(struct kmem_cache_node *n) |
2396 | { |
2397 | return atomic_long_read(&n->total_objects); |
2398 | } |
2399 | #endif /* CONFIG_SLUB_DEBUG */ |
2400 | |
2401 | #if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS) |
2402 | static unsigned long count_partial(struct kmem_cache_node *n, |
2403 | int (*get_count)(struct page *)) |
2404 | { |
2405 | unsigned long flags; |
2406 | unsigned long x = 0; |
2407 | struct page *page; |
2408 | |
2409 | spin_lock_irqsave(&n->list_lock, flags); |
2410 | list_for_each_entry(page, &n->partial, lru) |
2411 | x += get_count(page); |
2412 | spin_unlock_irqrestore(&n->list_lock, flags); |
2413 | return x; |
2414 | } |
2415 | #endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */ |
2416 | |
2417 | static noinline void |
2418 | slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) |
2419 | { |
2420 | #ifdef CONFIG_SLUB_DEBUG |
2421 | static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL, |
2422 | DEFAULT_RATELIMIT_BURST); |
2423 | int node; |
2424 | struct kmem_cache_node *n; |
2425 | |
2426 | if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs)) |
2427 | return; |
2428 | |
2429 | pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n" , |
2430 | nid, gfpflags, &gfpflags); |
2431 | pr_warn(" cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n" , |
2432 | s->name, s->object_size, s->size, oo_order(s->oo), |
2433 | oo_order(s->min)); |
2434 | |
2435 | if (oo_order(s->min) > get_order(s->object_size)) |
2436 | pr_warn(" %s debugging increased min order, use slub_debug=O to disable.\n" , |
2437 | s->name); |
2438 | |
2439 | for_each_kmem_cache_node(s, node, n) { |
2440 | unsigned long nr_slabs; |
2441 | unsigned long nr_objs; |
2442 | unsigned long nr_free; |
2443 | |
2444 | nr_free = count_partial(n, count_free); |
2445 | nr_slabs = node_nr_slabs(n); |
2446 | nr_objs = node_nr_objs(n); |
2447 | |
2448 | pr_warn(" node %d: slabs: %ld, objs: %ld, free: %ld\n" , |
2449 | node, nr_slabs, nr_objs, nr_free); |
2450 | } |
2451 | #endif |
2452 | } |
2453 | |
2454 | static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, |
2455 | int node, struct kmem_cache_cpu **pc) |
2456 | { |
2457 | void *freelist; |
2458 | struct kmem_cache_cpu *c = *pc; |
2459 | struct page *page; |
2460 | |
2461 | WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); |
2462 | |
2463 | freelist = get_partial(s, flags, node, c); |
2464 | |
2465 | if (freelist) |
2466 | return freelist; |
2467 | |
2468 | page = new_slab(s, flags, node); |
2469 | if (page) { |
2470 | c = raw_cpu_ptr(s->cpu_slab); |
2471 | if (c->page) |
2472 | flush_slab(s, c); |
2473 | |
2474 | /* |
2475 | * No other reference to the page yet so we can |
2476 | * muck around with it freely without cmpxchg |
2477 | */ |
2478 | freelist = page->freelist; |
2479 | page->freelist = NULL; |
2480 | |
2481 | stat(s, ALLOC_SLAB); |
2482 | c->page = page; |
2483 | *pc = c; |
2484 | } |
2485 | |
2486 | return freelist; |
2487 | } |
2488 | |
2489 | static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags) |
2490 | { |
2491 | if (unlikely(PageSlabPfmemalloc(page))) |
2492 | return gfp_pfmemalloc_allowed(gfpflags); |
2493 | |
2494 | return true; |
2495 | } |
2496 | |
2497 | /* |
2498 | * Check the page->freelist of a page and either transfer the freelist to the |
2499 | * per cpu freelist or deactivate the page. |
2500 | * |
2501 | * The page is still frozen if the return value is not NULL. |
2502 | * |
2503 | * If this function returns NULL then the page has been unfrozen. |
2504 | * |
2505 | * This function must be called with interrupt disabled. |
2506 | */ |
2507 | static inline void *get_freelist(struct kmem_cache *s, struct page *page) |
2508 | { |
2509 | struct page new; |
2510 | unsigned long counters; |
2511 | void *freelist; |
2512 | |
2513 | do { |
2514 | freelist = page->freelist; |
2515 | counters = page->counters; |
2516 | |
2517 | new.counters = counters; |
2518 | VM_BUG_ON(!new.frozen); |
2519 | |
2520 | new.inuse = page->objects; |
2521 | new.frozen = freelist != NULL; |
2522 | |
2523 | } while (!__cmpxchg_double_slab(s, page, |
2524 | freelist, counters, |
2525 | NULL, new.counters, |
2526 | "get_freelist" )); |
2527 | |
2528 | return freelist; |
2529 | } |
2530 | |
2531 | /* |
2532 | * Slow path. The lockless freelist is empty or we need to perform |
2533 | * debugging duties. |
2534 | * |
2535 | * Processing is still very fast if new objects have been freed to the |
2536 | * regular freelist. In that case we simply take over the regular freelist |
2537 | * as the lockless freelist and zap the regular freelist. |
2538 | * |
2539 | * If that is not working then we fall back to the partial lists. We take the |
2540 | * first element of the freelist as the object to allocate now and move the |
2541 | * rest of the freelist to the lockless freelist. |
2542 | * |
2543 | * And if we were unable to get a new slab from the partial slab lists then |
2544 | * we need to allocate a new slab. This is the slowest path since it involves |
2545 | * a call to the page allocator and the setup of a new slab. |
2546 | * |
2547 | * Version of __slab_alloc to use when we know that interrupts are |
2548 | * already disabled (which is the case for bulk allocation). |
2549 | */ |
2550 | static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, |
2551 | unsigned long addr, struct kmem_cache_cpu *c) |
2552 | { |
2553 | void *freelist; |
2554 | struct page *page; |
2555 | |
2556 | page = c->page; |
2557 | if (!page) |
2558 | goto new_slab; |
2559 | redo: |
2560 | |
2561 | if (unlikely(!node_match(page, node))) { |
2562 | int searchnode = node; |
2563 | |
2564 | if (node != NUMA_NO_NODE && !node_present_pages(node)) |
2565 | searchnode = node_to_mem_node(node); |
2566 | |
2567 | if (unlikely(!node_match(page, searchnode))) { |
2568 | stat(s, ALLOC_NODE_MISMATCH); |
2569 | deactivate_slab(s, page, c->freelist, c); |
2570 | goto new_slab; |
2571 | } |
2572 | } |
2573 | |
2574 | /* |
2575 | * By rights, we should be searching for a slab page that was |
2576 | * PFMEMALLOC but right now, we are losing the pfmemalloc |
2577 | * information when the page leaves the per-cpu allocator |
2578 | */ |
2579 | if (unlikely(!pfmemalloc_match(page, gfpflags))) { |
2580 | deactivate_slab(s, page, c->freelist, c); |
2581 | goto new_slab; |
2582 | } |
2583 | |
2584 | /* must check again c->freelist in case of cpu migration or IRQ */ |
2585 | freelist = c->freelist; |
2586 | if (freelist) |
2587 | goto load_freelist; |
2588 | |
2589 | freelist = get_freelist(s, page); |
2590 | |
2591 | if (!freelist) { |
2592 | c->page = NULL; |
2593 | stat(s, DEACTIVATE_BYPASS); |
2594 | goto new_slab; |
2595 | } |
2596 | |
2597 | stat(s, ALLOC_REFILL); |
2598 | |
2599 | load_freelist: |
2600 | /* |
2601 | * freelist is pointing to the list of objects to be used. |
2602 | * page is pointing to the page from which the objects are obtained. |
2603 | * That page must be frozen for per cpu allocations to work. |
2604 | */ |
2605 | VM_BUG_ON(!c->page->frozen); |
2606 | c->freelist = get_freepointer(s, freelist); |
2607 | c->tid = next_tid(c->tid); |
2608 | return freelist; |
2609 | |
2610 | new_slab: |
2611 | |
2612 | if (slub_percpu_partial(c)) { |
2613 | page = c->page = slub_percpu_partial(c); |
2614 | slub_set_percpu_partial(c, page); |
2615 | stat(s, CPU_PARTIAL_ALLOC); |
2616 | goto redo; |
2617 | } |
2618 | |
2619 | freelist = new_slab_objects(s, gfpflags, node, &c); |
2620 | |
2621 | if (unlikely(!freelist)) { |
2622 | slab_out_of_memory(s, gfpflags, node); |
2623 | return NULL; |
2624 | } |
2625 | |
2626 | page = c->page; |
2627 | if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) |
2628 | goto load_freelist; |
2629 | |
2630 | /* Only entered in the debug case */ |
2631 | if (kmem_cache_debug(s) && |
2632 | !alloc_debug_processing(s, page, freelist, addr)) |
2633 | goto new_slab; /* Slab failed checks. Next slab needed */ |
2634 | |
2635 | deactivate_slab(s, page, get_freepointer(s, freelist), c); |
2636 | return freelist; |
2637 | } |
2638 | |
2639 | /* |
2640 | * Another one that disabled interrupt and compensates for possible |
2641 | * cpu changes by refetching the per cpu area pointer. |
2642 | */ |
2643 | static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, |
2644 | unsigned long addr, struct kmem_cache_cpu *c) |
2645 | { |
2646 | void *p; |
2647 | unsigned long flags; |
2648 | |
2649 | local_irq_save(flags); |
2650 | #ifdef CONFIG_PREEMPT |
2651 | /* |
2652 | * We may have been preempted and rescheduled on a different |
2653 | * cpu before disabling interrupts. Need to reload cpu area |
2654 | * pointer. |
2655 | */ |
2656 | c = this_cpu_ptr(s->cpu_slab); |
2657 | #endif |
2658 | |
2659 | p = ___slab_alloc(s, gfpflags, node, addr, c); |
2660 | local_irq_restore(flags); |
2661 | return p; |
2662 | } |
2663 | |
2664 | /* |
2665 | * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc) |
2666 | * have the fastpath folded into their functions. So no function call |
2667 | * overhead for requests that can be satisfied on the fastpath. |
2668 | * |
2669 | * The fastpath works by first checking if the lockless freelist can be used. |
2670 | * If not then __slab_alloc is called for slow processing. |
2671 | * |
2672 | * Otherwise we can simply pick the next object from the lockless free list. |
2673 | */ |
2674 | static __always_inline void *slab_alloc_node(struct kmem_cache *s, |
2675 | gfp_t gfpflags, int node, unsigned long addr) |
2676 | { |
2677 | void *object; |
2678 | struct kmem_cache_cpu *c; |
2679 | struct page *page; |
2680 | unsigned long tid; |
2681 | |
2682 | s = slab_pre_alloc_hook(s, gfpflags); |
2683 | if (!s) |
2684 | return NULL; |
2685 | redo: |
2686 | /* |
2687 | * Must read kmem_cache cpu data via this cpu ptr. Preemption is |
2688 | * enabled. We may switch back and forth between cpus while |
2689 | * reading from one cpu area. That does not matter as long |
2690 | * as we end up on the original cpu again when doing the cmpxchg. |
2691 | * |
2692 | * We should guarantee that tid and kmem_cache are retrieved on |
2693 | * the same cpu. It could be different if CONFIG_PREEMPT so we need |
2694 | * to check if it is matched or not. |
2695 | */ |
2696 | do { |
2697 | tid = this_cpu_read(s->cpu_slab->tid); |
2698 | c = raw_cpu_ptr(s->cpu_slab); |
2699 | } while (IS_ENABLED(CONFIG_PREEMPT) && |
2700 | unlikely(tid != READ_ONCE(c->tid))); |
2701 | |
2702 | /* |
2703 | * Irqless object alloc/free algorithm used here depends on sequence |
2704 | * of fetching cpu_slab's data. tid should be fetched before anything |
2705 | * on c to guarantee that object and page associated with previous tid |
2706 | * won't be used with current tid. If we fetch tid first, object and |
2707 | * page could be one associated with next tid and our alloc/free |
2708 | * request will be failed. In this case, we will retry. So, no problem. |
2709 | */ |
2710 | barrier(); |
2711 | |
2712 | /* |
2713 | * The transaction ids are globally unique per cpu and per operation on |
2714 | * a per cpu queue. Thus they can be guarantee that the cmpxchg_double |
2715 | * occurs on the right processor and that there was no operation on the |
2716 | * linked list in between. |
2717 | */ |
2718 | |
2719 | object = c->freelist; |
2720 | page = c->page; |
2721 | if (unlikely(!object || !node_match(page, node))) { |
2722 | object = __slab_alloc(s, gfpflags, node, addr, c); |
2723 | stat(s, ALLOC_SLOWPATH); |
2724 | } else { |
2725 | void *next_object = get_freepointer_safe(s, object); |
2726 | |
2727 | /* |
2728 | * The cmpxchg will only match if there was no additional |
2729 | * operation and if we are on the right processor. |
2730 | * |
2731 | * The cmpxchg does the following atomically (without lock |
2732 | * semantics!) |
2733 | * 1. Relocate first pointer to the current per cpu area. |
2734 | * 2. Verify that tid and freelist have not been changed |
2735 | * 3. If they were not changed replace tid and freelist |
2736 | * |
2737 | * Since this is without lock semantics the protection is only |
2738 | * against code executing on this cpu *not* from access by |
2739 | * other cpus. |
2740 | */ |
2741 | if (unlikely(!this_cpu_cmpxchg_double( |
2742 | s->cpu_slab->freelist, s->cpu_slab->tid, |
2743 | object, tid, |
2744 | next_object, next_tid(tid)))) { |
2745 | |
2746 | note_cmpxchg_failure("slab_alloc" , s, tid); |
2747 | goto redo; |
2748 | } |
2749 | prefetch_freepointer(s, next_object); |
2750 | stat(s, ALLOC_FASTPATH); |
2751 | } |
2752 | |
2753 | if (unlikely(gfpflags & __GFP_ZERO) && object) |
2754 | memset(object, 0, s->object_size); |
2755 | |
2756 | slab_post_alloc_hook(s, gfpflags, 1, &object); |
2757 | |
2758 | return object; |
2759 | } |
2760 | |
2761 | static __always_inline void *slab_alloc(struct kmem_cache *s, |
2762 | gfp_t gfpflags, unsigned long addr) |
2763 | { |
2764 | return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr); |
2765 | } |
2766 | |
2767 | void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags) |
2768 | { |
2769 | void *ret = slab_alloc(s, gfpflags, _RET_IP_); |
2770 | |
2771 | trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size, |
2772 | s->size, gfpflags); |
2773 | |
2774 | return ret; |
2775 | } |
2776 | EXPORT_SYMBOL(kmem_cache_alloc); |
2777 | |
2778 | #ifdef CONFIG_TRACING |
2779 | void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) |
2780 | { |
2781 | void *ret = slab_alloc(s, gfpflags, _RET_IP_); |
2782 | trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags); |
2783 | ret = kasan_kmalloc(s, ret, size, gfpflags); |
2784 | return ret; |
2785 | } |
2786 | EXPORT_SYMBOL(kmem_cache_alloc_trace); |
2787 | #endif |
2788 | |
2789 | #ifdef CONFIG_NUMA |
2790 | void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node) |
2791 | { |
2792 | void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); |
2793 | |
2794 | trace_kmem_cache_alloc_node(_RET_IP_, ret, |
2795 | s->object_size, s->size, gfpflags, node); |
2796 | |
2797 | return ret; |
2798 | } |
2799 | EXPORT_SYMBOL(kmem_cache_alloc_node); |
2800 | |
2801 | #ifdef CONFIG_TRACING |
2802 | void *kmem_cache_alloc_node_trace(struct kmem_cache *s, |
2803 | gfp_t gfpflags, |
2804 | int node, size_t size) |
2805 | { |
2806 | void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); |
2807 | |
2808 | trace_kmalloc_node(_RET_IP_, ret, |
2809 | size, s->size, gfpflags, node); |
2810 | |
2811 | ret = kasan_kmalloc(s, ret, size, gfpflags); |
2812 | return ret; |
2813 | } |
2814 | EXPORT_SYMBOL(kmem_cache_alloc_node_trace); |
2815 | #endif |
2816 | #endif |
2817 | |
2818 | /* |
2819 | * Slow path handling. This may still be called frequently since objects |
2820 | * have a longer lifetime than the cpu slabs in most processing loads. |
2821 | * |
2822 | * So we still attempt to reduce cache line usage. Just take the slab |
2823 | * lock and free the item. If there is no additional partial page |
2824 | * handling required then we can return immediately. |
2825 | */ |
2826 | static void __slab_free(struct kmem_cache *s, struct page *page, |
2827 | void *head, void *tail, int cnt, |
2828 | unsigned long addr) |
2829 | |
2830 | { |
2831 | void *prior; |
2832 | int was_frozen; |
2833 | struct page new; |
2834 | unsigned long counters; |
2835 | struct kmem_cache_node *n = NULL; |
2836 | unsigned long uninitialized_var(flags); |
2837 | |
2838 | stat(s, FREE_SLOWPATH); |
2839 | |
2840 | if (kmem_cache_debug(s) && |
2841 | !free_debug_processing(s, page, head, tail, cnt, addr)) |
2842 | return; |
2843 | |
2844 | do { |
2845 | if (unlikely(n)) { |
2846 | spin_unlock_irqrestore(&n->list_lock, flags); |
2847 | n = NULL; |
2848 | } |
2849 | prior = page->freelist; |
2850 | counters = page->counters; |
2851 | set_freepointer(s, tail, prior); |
2852 | new.counters = counters; |
2853 | was_frozen = new.frozen; |
2854 | new.inuse -= cnt; |
2855 | if ((!new.inuse || !prior) && !was_frozen) { |
2856 | |
2857 | if (kmem_cache_has_cpu_partial(s) && !prior) { |
2858 | |
2859 | /* |
2860 | * Slab was on no list before and will be |
2861 | * partially empty |
2862 | * We can defer the list move and instead |
2863 | * freeze it. |
2864 | */ |
2865 | new.frozen = 1; |
2866 | |
2867 | } else { /* Needs to be taken off a list */ |
2868 | |
2869 | n = get_node(s, page_to_nid(page)); |
2870 | /* |
2871 | * Speculatively acquire the list_lock. |
2872 | * If the cmpxchg does not succeed then we may |
2873 | * drop the list_lock without any processing. |
2874 | * |
2875 | * Otherwise the list_lock will synchronize with |
2876 | * other processors updating the list of slabs. |
2877 | */ |
2878 | spin_lock_irqsave(&n->list_lock, flags); |
2879 | |
2880 | } |
2881 | } |
2882 | |
2883 | } while (!cmpxchg_double_slab(s, page, |
2884 | prior, counters, |
2885 | head, new.counters, |
2886 | "__slab_free" )); |
2887 | |
2888 | if (likely(!n)) { |
2889 | |
2890 | /* |
2891 | * If we just froze the page then put it onto the |
2892 | * per cpu partial list. |
2893 | */ |
2894 | if (new.frozen && !was_frozen) { |
2895 | put_cpu_partial(s, page, 1); |
2896 | stat(s, CPU_PARTIAL_FREE); |
2897 | } |
2898 | /* |
2899 | * The list lock was not taken therefore no list |
2900 | * activity can be necessary. |
2901 | */ |
2902 | if (was_frozen) |
2903 | stat(s, FREE_FROZEN); |
2904 | return; |
2905 | } |
2906 | |
2907 | if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) |
2908 | goto slab_empty; |
2909 | |
2910 | /* |
2911 | * Objects left in the slab. If it was not on the partial list before |
2912 | * then add it. |
2913 | */ |
2914 | if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) { |
2915 | if (kmem_cache_debug(s)) |
2916 | remove_full(s, n, page); |
2917 | add_partial(n, page, DEACTIVATE_TO_TAIL); |
2918 | stat(s, FREE_ADD_PARTIAL); |
2919 | } |
2920 | spin_unlock_irqrestore(&n->list_lock, flags); |
2921 | return; |
2922 | |
2923 | slab_empty: |
2924 | if (prior) { |
2925 | /* |
2926 | * Slab on the partial list. |
2927 | */ |
2928 | remove_partial(n, page); |
2929 | stat(s, FREE_REMOVE_PARTIAL); |
2930 | } else { |
2931 | /* Slab must be on the full list */ |
2932 | remove_full(s, n, page); |
2933 | } |
2934 | |
2935 | spin_unlock_irqrestore(&n->list_lock, flags); |
2936 | stat(s, FREE_SLAB); |
2937 | discard_slab(s, page); |
2938 | } |
2939 | |
2940 | /* |
2941 | * Fastpath with forced inlining to produce a kfree and kmem_cache_free that |
2942 | * can perform fastpath freeing without additional function calls. |
2943 | * |
2944 | * The fastpath is only possible if we are freeing to the current cpu slab |
2945 | * of this processor. This typically the case if we have just allocated |
2946 | * the item before. |
2947 | * |
2948 | * If fastpath is not possible then fall back to __slab_free where we deal |
2949 | * with all sorts of special processing. |
2950 | * |
2951 | * Bulk free of a freelist with several objects (all pointing to the |
2952 | * same page) possible by specifying head and tail ptr, plus objects |
2953 | * count (cnt). Bulk free indicated by tail pointer being set. |
2954 | */ |
2955 | static __always_inline void do_slab_free(struct kmem_cache *s, |
2956 | struct page *page, void *head, void *tail, |
2957 | int cnt, unsigned long addr) |
2958 | { |
2959 | void *tail_obj = tail ? : head; |
2960 | struct kmem_cache_cpu *c; |
2961 | unsigned long tid; |
2962 | redo: |
2963 | /* |
2964 | * Determine the currently cpus per cpu slab. |
2965 | * The cpu may change afterward. However that does not matter since |
2966 | * data is retrieved via this pointer. If we are on the same cpu |
2967 | * during the cmpxchg then the free will succeed. |
2968 | */ |
2969 | do { |
2970 | tid = this_cpu_read(s->cpu_slab->tid); |
2971 | c = raw_cpu_ptr(s->cpu_slab); |
2972 | } while (IS_ENABLED(CONFIG_PREEMPT) && |
2973 | unlikely(tid != READ_ONCE(c->tid))); |
2974 | |
2975 | /* Same with comment on barrier() in slab_alloc_node() */ |
2976 | barrier(); |
2977 | |
2978 | if (likely(page == c->page)) { |
2979 | set_freepointer(s, tail_obj, c->freelist); |
2980 | |
2981 | if (unlikely(!this_cpu_cmpxchg_double( |
2982 | s->cpu_slab->freelist, s->cpu_slab->tid, |
2983 | c->freelist, tid, |
2984 | head, next_tid(tid)))) { |
2985 | |
2986 | note_cmpxchg_failure("slab_free" , s, tid); |
2987 | goto redo; |
2988 | } |
2989 | stat(s, FREE_FASTPATH); |
2990 | } else |
2991 | __slab_free(s, page, head, tail_obj, cnt, addr); |
2992 | |
2993 | } |
2994 | |
2995 | static __always_inline void slab_free(struct kmem_cache *s, struct page *page, |
2996 | void *head, void *tail, int cnt, |
2997 | unsigned long addr) |
2998 | { |
2999 | /* |
3000 | * With KASAN enabled slab_free_freelist_hook modifies the freelist |
3001 | * to remove objects, whose reuse must be delayed. |
3002 | */ |
3003 | if (slab_free_freelist_hook(s, &head, &tail)) |
3004 | do_slab_free(s, page, head, tail, cnt, addr); |
3005 | } |
3006 | |
3007 | #ifdef CONFIG_KASAN_GENERIC |
3008 | void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr) |
3009 | { |
3010 | do_slab_free(cache, virt_to_head_page(x), x, NULL, 1, addr); |
3011 | } |
3012 | #endif |
3013 | |
3014 | void kmem_cache_free(struct kmem_cache *s, void *x) |
3015 | { |
3016 | s = cache_from_obj(s, x); |
3017 | if (!s) |
3018 | return; |
3019 | slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_); |
3020 | trace_kmem_cache_free(_RET_IP_, x); |
3021 | } |
3022 | EXPORT_SYMBOL(kmem_cache_free); |
3023 | |
3024 | struct detached_freelist { |
3025 | struct page *page; |
3026 | void *tail; |
3027 | void *freelist; |
3028 | int cnt; |
3029 | struct kmem_cache *s; |
3030 | }; |
3031 | |
3032 | /* |
3033 | * This function progressively scans the array with free objects (with |
3034 | * a limited look ahead) and extract objects belonging to the same |
3035 | * page. It builds a detached freelist directly within the given |
3036 | * page/objects. This can happen without any need for |
3037 | * synchronization, because the objects are owned by running process. |
3038 | * The freelist is build up as a single linked list in the objects. |
3039 | * The idea is, that this detached freelist can then be bulk |
3040 | * transferred to the real freelist(s), but only requiring a single |
3041 | * synchronization primitive. Look ahead in the array is limited due |
3042 | * to performance reasons. |
3043 | */ |
3044 | static inline |
3045 | int build_detached_freelist(struct kmem_cache *s, size_t size, |
3046 | void **p, struct detached_freelist *df) |
3047 | { |
3048 | size_t first_skipped_index = 0; |
3049 | int lookahead = 3; |
3050 | void *object; |
3051 | struct page *page; |
3052 | |
3053 | /* Always re-init detached_freelist */ |
3054 | df->page = NULL; |
3055 | |
3056 | do { |
3057 | object = p[--size]; |
3058 | /* Do we need !ZERO_OR_NULL_PTR(object) here? (for kfree) */ |
3059 | } while (!object && size); |
3060 | |
3061 | if (!object) |
3062 | return 0; |
3063 | |
3064 | page = virt_to_head_page(object); |
3065 | if (!s) { |
3066 | /* Handle kalloc'ed objects */ |
3067 | if (unlikely(!PageSlab(page))) { |
3068 | BUG_ON(!PageCompound(page)); |
3069 | kfree_hook(object); |
3070 | __free_pages(page, compound_order(page)); |
3071 | p[size] = NULL; /* mark object processed */ |
3072 | return size; |
3073 | } |
3074 | /* Derive kmem_cache from object */ |
3075 | df->s = page->slab_cache; |
3076 | } else { |
3077 | df->s = cache_from_obj(s, object); /* Support for memcg */ |
3078 | } |
3079 | |
3080 | /* Start new detached freelist */ |
3081 | df->page = page; |
3082 | set_freepointer(df->s, object, NULL); |
3083 | df->tail = object; |
3084 | df->freelist = object; |
3085 | p[size] = NULL; /* mark object processed */ |
3086 | df->cnt = 1; |
3087 | |
3088 | while (size) { |
3089 | object = p[--size]; |
3090 | if (!object) |
3091 | continue; /* Skip processed objects */ |
3092 | |
3093 | /* df->page is always set at this point */ |
3094 | if (df->page == virt_to_head_page(object)) { |
3095 | /* Opportunity build freelist */ |
3096 | set_freepointer(df->s, object, df->freelist); |
3097 | df->freelist = object; |
3098 | df->cnt++; |
3099 | p[size] = NULL; /* mark object processed */ |
3100 | |
3101 | continue; |
3102 | } |
3103 | |
3104 | /* Limit look ahead search */ |
3105 | if (!--lookahead) |
3106 | break; |
3107 | |
3108 | if (!first_skipped_index) |
3109 | first_skipped_index = size + 1; |
3110 | } |
3111 | |
3112 | return first_skipped_index; |
3113 | } |
3114 | |
3115 | /* Note that interrupts must be enabled when calling this function. */ |
3116 | void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p) |
3117 | { |
3118 | if (WARN_ON(!size)) |
3119 | return; |
3120 | |
3121 | do { |
3122 | struct detached_freelist df; |
3123 | |
3124 | size = build_detached_freelist(s, size, p, &df); |
3125 | if (!df.page) |
3126 | continue; |
3127 | |
3128 | slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_); |
3129 | } while (likely(size)); |
3130 | } |
3131 | EXPORT_SYMBOL(kmem_cache_free_bulk); |
3132 | |
3133 | /* Note that interrupts must be enabled when calling this function. */ |
3134 | int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, |
3135 | void **p) |
3136 | { |
3137 | struct kmem_cache_cpu *c; |
3138 | int i; |
3139 | |
3140 | /* memcg and kmem_cache debug support */ |
3141 | s = slab_pre_alloc_hook(s, flags); |
3142 | if (unlikely(!s)) |
3143 | return false; |
3144 | /* |
3145 | * Drain objects in the per cpu slab, while disabling local |
3146 | * IRQs, which protects against PREEMPT and interrupts |
3147 | * handlers invoking normal fastpath. |
3148 | */ |
3149 | local_irq_disable(); |
3150 | c = this_cpu_ptr(s->cpu_slab); |
3151 | |
3152 | for (i = 0; i < size; i++) { |
3153 | void *object = c->freelist; |
3154 | |
3155 | if (unlikely(!object)) { |
3156 | /* |
3157 | * Invoking slow path likely have side-effect |
3158 | * of re-populating per CPU c->freelist |
3159 | */ |
3160 | p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE, |
3161 | _RET_IP_, c); |
3162 | if (unlikely(!p[i])) |
3163 | goto error; |
3164 | |
3165 | c = this_cpu_ptr(s->cpu_slab); |
3166 | continue; /* goto for-loop */ |
3167 | } |
3168 | c->freelist = get_freepointer(s, object); |
3169 | p[i] = object; |
3170 | } |
3171 | c->tid = next_tid(c->tid); |
3172 | local_irq_enable(); |
3173 | |
3174 | /* Clear memory outside IRQ disabled fastpath loop */ |
3175 | if (unlikely(flags & __GFP_ZERO)) { |
3176 | int j; |
3177 | |
3178 | for (j = 0; j < i; j++) |
3179 | memset(p[j], 0, s->object_size); |
3180 | } |
3181 | |
3182 | /* memcg and kmem_cache debug support */ |
3183 | slab_post_alloc_hook(s, flags, size, p); |
3184 | return i; |
3185 | error: |
3186 | local_irq_enable(); |
3187 | slab_post_alloc_hook(s, flags, i, p); |
3188 | __kmem_cache_free_bulk(s, i, p); |
3189 | return 0; |
3190 | } |
3191 | EXPORT_SYMBOL(kmem_cache_alloc_bulk); |
3192 | |
3193 | |
3194 | /* |
3195 | * Object placement in a slab is made very easy because we always start at |
3196 | * offset 0. If we tune the size of the object to the alignment then we can |
3197 | * get the required alignment by putting one properly sized object after |
3198 | * another. |
3199 | * |
3200 | * Notice that the allocation order determines the sizes of the per cpu |
3201 | * caches. Each processor has always one slab available for allocations. |
3202 | * Increasing the allocation order reduces the number of times that slabs |
3203 | * must be moved on and off the partial lists and is therefore a factor in |
3204 | * locking overhead. |
3205 | */ |
3206 | |
3207 | /* |
3208 | * Mininum / Maximum order of slab pages. This influences locking overhead |
3209 | * and slab fragmentation. A higher order reduces the number of partial slabs |
3210 | * and increases the number of allocations possible without having to |
3211 | * take the list_lock. |
3212 | */ |
3213 | static unsigned int slub_min_order; |
3214 | static unsigned int slub_max_order = PAGE_ALLOC_COSTLY_ORDER; |
3215 | static unsigned int slub_min_objects; |
3216 | |
3217 | /* |
3218 | * Calculate the order of allocation given an slab object size. |
3219 | * |
3220 | * The order of allocation has significant impact on performance and other |
3221 | * system components. Generally order 0 allocations should be preferred since |
3222 | * order 0 does not cause fragmentation in the page allocator. Larger objects |
3223 | * be problematic to put into order 0 slabs because there may be too much |
3224 | * unused space left. We go to a higher order if more than 1/16th of the slab |
3225 | * would be wasted. |
3226 | * |
3227 | * In order to reach satisfactory performance we must ensure that a minimum |
3228 | * number of objects is in one slab. Otherwise we may generate too much |
3229 | * activity on the partial lists which requires taking the list_lock. This is |
3230 | * less a concern for large slabs though which are rarely used. |
3231 | * |
3232 | * slub_max_order specifies the order where we begin to stop considering the |
3233 | * number of objects in a slab as critical. If we reach slub_max_order then |
3234 | * we try to keep the page order as low as possible. So we accept more waste |
3235 | * of space in favor of a small page order. |
3236 | * |
3237 | * Higher order allocations also allow the placement of more objects in a |
3238 | * slab and thereby reduce object handling overhead. If the user has |
3239 | * requested a higher mininum order then we start with that one instead of |
3240 | * the smallest order which will fit the object. |
3241 | */ |
3242 | static inline unsigned int slab_order(unsigned int size, |
3243 | unsigned int min_objects, unsigned int max_order, |
3244 | unsigned int fract_leftover) |
3245 | { |
3246 | unsigned int min_order = slub_min_order; |
3247 | unsigned int order; |
3248 | |
3249 | if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE) |
3250 | return get_order(size * MAX_OBJS_PER_PAGE) - 1; |
3251 | |
3252 | for (order = max(min_order, (unsigned int)get_order(min_objects * size)); |
3253 | order <= max_order; order++) { |
3254 | |
3255 | unsigned int slab_size = (unsigned int)PAGE_SIZE << order; |
3256 | unsigned int rem; |
3257 | |
3258 | rem = slab_size % size; |
3259 | |
3260 | if (rem <= slab_size / fract_leftover) |
3261 | break; |
3262 | } |
3263 | |
3264 | return order; |
3265 | } |
3266 | |
3267 | static inline int calculate_order(unsigned int size) |
3268 | { |
3269 | unsigned int order; |
3270 | unsigned int min_objects; |
3271 | unsigned int max_objects; |
3272 | |
3273 | /* |
3274 | * Attempt to find best configuration for a slab. This |
3275 | * works by first attempting to generate a layout with |
3276 | * the best configuration and backing off gradually. |
3277 | * |
3278 | * First we increase the acceptable waste in a slab. Then |
3279 | * we reduce the minimum objects required in a slab. |
3280 | */ |
3281 | min_objects = slub_min_objects; |
3282 | if (!min_objects) |
3283 | min_objects = 4 * (fls(nr_cpu_ids) + 1); |
3284 | max_objects = order_objects(slub_max_order, size); |
3285 | min_objects = min(min_objects, max_objects); |
3286 | |
3287 | while (min_objects > 1) { |
3288 | unsigned int fraction; |
3289 | |
3290 | fraction = 16; |
3291 | while (fraction >= 4) { |
3292 | order = slab_order(size, min_objects, |
3293 | slub_max_order, fraction); |
3294 | if (order <= slub_max_order) |
3295 | return order; |
3296 | fraction /= 2; |
3297 | } |
3298 | min_objects--; |
3299 | } |
3300 | |
3301 | /* |
3302 | * We were unable to place multiple objects in a slab. Now |
3303 | * lets see if we can place a single object there. |
3304 | */ |
3305 | order = slab_order(size, 1, slub_max_order, 1); |
3306 | if (order <= slub_max_order) |
3307 | return order; |
3308 | |
3309 | /* |
3310 | * Doh this slab cannot be placed using slub_max_order. |
3311 | */ |
3312 | order = slab_order(size, 1, MAX_ORDER, 1); |
3313 | if (order < MAX_ORDER) |
3314 | return order; |
3315 | return -ENOSYS; |
3316 | } |
3317 | |
3318 | static void |
3319 | init_kmem_cache_node(struct kmem_cache_node *n) |
3320 | { |
3321 | n->nr_partial = 0; |
3322 | spin_lock_init(&n->list_lock); |
3323 | INIT_LIST_HEAD(&n->partial); |
3324 | #ifdef CONFIG_SLUB_DEBUG |
3325 | atomic_long_set(&n->nr_slabs, 0); |
3326 | atomic_long_set(&n->total_objects, 0); |
3327 | INIT_LIST_HEAD(&n->full); |
3328 | #endif |
3329 | } |
3330 | |
3331 | static inline int alloc_kmem_cache_cpus(struct kmem_cache *s) |
3332 | { |
3333 | BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE < |
3334 | KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu)); |
3335 | |
3336 | /* |
3337 | * Must align to double word boundary for the double cmpxchg |
3338 | * instructions to work; see __pcpu_double_call_return_bool(). |
3339 | */ |
3340 | s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu), |
3341 | 2 * sizeof(void *)); |
3342 | |
3343 | if (!s->cpu_slab) |
3344 | return 0; |
3345 | |
3346 | init_kmem_cache_cpus(s); |
3347 | |
3348 | return 1; |
3349 | } |
3350 | |
3351 | static struct kmem_cache *kmem_cache_node; |
3352 | |
3353 | /* |
3354 | * No kmalloc_node yet so do it by hand. We know that this is the first |
3355 | * slab on the node for this slabcache. There are no concurrent accesses |
3356 | * possible. |
3357 | * |
3358 | * Note that this function only works on the kmem_cache_node |
3359 | * when allocating for the kmem_cache_node. This is used for bootstrapping |
3360 | * memory on a fresh node that has no slab structures yet. |
3361 | */ |
3362 | static void early_kmem_cache_node_alloc(int node) |
3363 | { |
3364 | struct page *page; |
3365 | struct kmem_cache_node *n; |
3366 | |
3367 | BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node)); |
3368 | |
3369 | page = new_slab(kmem_cache_node, GFP_NOWAIT, node); |
3370 | |
3371 | BUG_ON(!page); |
3372 | if (page_to_nid(page) != node) { |
3373 | pr_err("SLUB: Unable to allocate memory from node %d\n" , node); |
3374 | pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n" ); |
3375 | } |
3376 | |
3377 | n = page->freelist; |
3378 | BUG_ON(!n); |
3379 | #ifdef CONFIG_SLUB_DEBUG |
3380 | init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); |
3381 | init_tracking(kmem_cache_node, n); |
3382 | #endif |
3383 | n = kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node), |
3384 | GFP_KERNEL); |
3385 | page->freelist = get_freepointer(kmem_cache_node, n); |
3386 | page->inuse = 1; |
3387 | page->frozen = 0; |
3388 | kmem_cache_node->node[node] = n; |
3389 | init_kmem_cache_node(n); |
3390 | inc_slabs_node(kmem_cache_node, node, page->objects); |
3391 | |
3392 | /* |
3393 | * No locks need to be taken here as it has just been |
3394 | * initialized and there is no concurrent access. |
3395 | */ |
3396 | __add_partial(n, page, DEACTIVATE_TO_HEAD); |
3397 | } |
3398 | |
3399 | static void free_kmem_cache_nodes(struct kmem_cache *s) |
3400 | { |
3401 | int node; |
3402 | struct kmem_cache_node *n; |
3403 | |
3404 | for_each_kmem_cache_node(s, node, n) { |
3405 | s->node[node] = NULL; |
3406 | kmem_cache_free(kmem_cache_node, n); |
3407 | } |
3408 | } |
3409 | |
3410 | void __kmem_cache_release(struct kmem_cache *s) |
3411 | { |
3412 | cache_random_seq_destroy(s); |
3413 | free_percpu(s->cpu_slab); |
3414 | free_kmem_cache_nodes(s); |
3415 | } |
3416 | |
3417 | static int init_kmem_cache_nodes(struct kmem_cache *s) |
3418 | { |
3419 | int node; |
3420 | |
3421 | for_each_node_state(node, N_NORMAL_MEMORY) { |
3422 | struct kmem_cache_node *n; |
3423 | |
3424 | if (slab_state == DOWN) { |
3425 | early_kmem_cache_node_alloc(node); |
3426 | continue; |
3427 | } |
3428 | n = kmem_cache_alloc_node(kmem_cache_node, |
3429 | GFP_KERNEL, node); |
3430 | |
3431 | if (!n) { |
3432 | free_kmem_cache_nodes(s); |
3433 | return 0; |
3434 | } |
3435 | |
3436 | init_kmem_cache_node(n); |
3437 | s->node[node] = n; |
3438 | } |
3439 | return 1; |
3440 | } |
3441 | |
3442 | static void set_min_partial(struct kmem_cache *s, unsigned long min) |
3443 | { |
3444 | if ( |
---|