1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
4 * Copyright (C) 2007 The Regents of the University of California.
5 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
6 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
7 * UCRL-CODE-235197
8 *
9 * This file is part of the SPL, Solaris Porting Layer.
10 *
11 * The SPL is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the
13 * Free Software Foundation; either version 2 of the License, or (at your
14 * option) any later version.
15 *
16 * The SPL is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 * for more details.
20 *
21 * You should have received a copy of the GNU General Public License along
22 * with the SPL. If not, see <http://www.gnu.org/licenses/>.
23 */
24
25 #include <sys/debug.h>
26 #include <sys/sysmacros.h>
27 #include <sys/kmem.h>
28 #include <sys/vmem.h>
29
30 /*
31 * As a general rule kmem_alloc() allocations should be small, preferably
32 * just a few pages since they must by physically contiguous. Therefore, a
33 * rate limited warning will be printed to the console for any kmem_alloc()
34 * which exceeds a reasonable threshold.
35 *
36 * The default warning threshold is set to sixteen pages but capped at 64K to
37 * accommodate systems using large pages. This value was selected to be small
38 * enough to ensure the largest allocations are quickly noticed and fixed.
39 * But large enough to avoid logging any warnings when a allocation size is
40 * larger than optimal but not a serious concern. Since this value is tunable,
41 * developers are encouraged to set it lower when testing so any new largish
42 * allocations are quickly caught. These warnings may be disabled by setting
43 * the threshold to zero.
44 */
45 unsigned int spl_kmem_alloc_warn = MIN(16 * PAGE_SIZE, 64 * 1024);
46 module_param(spl_kmem_alloc_warn, uint, 0644);
47 MODULE_PARM_DESC(spl_kmem_alloc_warn,
48 "Warning threshold in bytes for a kmem_alloc()");
49 EXPORT_SYMBOL(spl_kmem_alloc_warn);
50
51 /*
52 * Large kmem_alloc() allocations will fail if they exceed KMALLOC_MAX_SIZE.
53 * Allocations which are marginally smaller than this limit may succeed but
54 * should still be avoided due to the expense of locating a contiguous range
55 * of free pages. Therefore, a maximum kmem size with reasonable safely
56 * margin of 4x is set. Kmem_alloc() allocations larger than this maximum
57 * will quickly fail. Vmem_alloc() allocations less than or equal to this
58 * value will use kmalloc(), but shift to vmalloc() when exceeding this value.
59 */
60 unsigned int spl_kmem_alloc_max = (KMALLOC_MAX_SIZE >> 2);
61 module_param(spl_kmem_alloc_max, uint, 0644);
62 MODULE_PARM_DESC(spl_kmem_alloc_max,
63 "Maximum size in bytes for a kmem_alloc()");
64 EXPORT_SYMBOL(spl_kmem_alloc_max);
65
66 int
kmem_debugging(void)67 kmem_debugging(void)
68 {
69 return (0);
70 }
71 EXPORT_SYMBOL(kmem_debugging);
72
73 char *
kmem_vasprintf(const char * fmt,va_list ap)74 kmem_vasprintf(const char *fmt, va_list ap)
75 {
76 va_list aq;
77 char *ptr;
78
79 do {
80 va_copy(aq, ap);
81 ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, aq);
82 va_end(aq);
83 } while (ptr == NULL);
84
85 return (ptr);
86 }
87 EXPORT_SYMBOL(kmem_vasprintf);
88
89 char *
kmem_asprintf(const char * fmt,...)90 kmem_asprintf(const char *fmt, ...)
91 {
92 va_list ap;
93 char *ptr;
94
95 do {
96 va_start(ap, fmt);
97 ptr = kvasprintf(kmem_flags_convert(KM_SLEEP), fmt, ap);
98 va_end(ap);
99 } while (ptr == NULL);
100
101 return (ptr);
102 }
103 EXPORT_SYMBOL(kmem_asprintf);
104
105 static char *
__strdup(const char * str,int flags)106 __strdup(const char *str, int flags)
107 {
108 char *ptr;
109 int n;
110
111 n = strlen(str);
112 ptr = kmalloc(n + 1, kmem_flags_convert(flags));
113 if (ptr)
114 memcpy(ptr, str, n + 1);
115
116 return (ptr);
117 }
118
119 char *
kmem_strdup(const char * str)120 kmem_strdup(const char *str)
121 {
122 return (__strdup(str, KM_SLEEP));
123 }
124 EXPORT_SYMBOL(kmem_strdup);
125
126 void
kmem_strfree(char * str)127 kmem_strfree(char *str)
128 {
129 kfree(str);
130 }
131 EXPORT_SYMBOL(kmem_strfree);
132
133 void *
spl_kvmalloc(size_t size,gfp_t lflags)134 spl_kvmalloc(size_t size, gfp_t lflags)
135 {
136 /*
137 * GFP_KERNEL allocations can safely use kvmalloc which may
138 * improve performance by avoiding a) high latency caused by
139 * vmalloc's on-access allocation, b) performance loss due to
140 * MMU memory address mapping and c) vmalloc locking overhead.
141 * This has the side-effect that the slab statistics will
142 * incorrectly report this as a vmem allocation, but that is
143 * purely cosmetic.
144 */
145 if ((lflags & GFP_KERNEL) == GFP_KERNEL)
146 return (kvmalloc(size, lflags));
147
148 gfp_t kmalloc_lflags = lflags;
149
150 if (size > PAGE_SIZE) {
151 /*
152 * We need to set __GFP_NOWARN here since spl_kvmalloc is not
153 * only called by spl_kmem_alloc_impl but can be called
154 * directly with custom lflags, too. In that case
155 * kmem_flags_convert does not get called, which would
156 * implicitly set __GFP_NOWARN.
157 */
158 kmalloc_lflags |= __GFP_NOWARN;
159
160 /*
161 * N.B. __GFP_RETRY_MAYFAIL is supported only for large
162 * e (>32kB) allocations.
163 *
164 * We have to override __GFP_RETRY_MAYFAIL by __GFP_NORETRY
165 * for !costly requests because there is no other way to tell
166 * the allocator that we want to fail rather than retry
167 * endlessly.
168 */
169 if (!(kmalloc_lflags & __GFP_RETRY_MAYFAIL) ||
170 (size <= PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
171 kmalloc_lflags |= __GFP_NORETRY;
172 }
173 }
174
175 /*
176 * We first try kmalloc - even for big sizes - and fall back to
177 * spl_vmalloc if that fails.
178 *
179 * For non-__GFP-RECLAIM allocations we always stick to
180 * kmalloc_node, and fail when kmalloc is not successful (returns
181 * NULL).
182 * We cannot fall back to spl_vmalloc in this case because spl_vmalloc
183 * internally uses GPF_KERNEL allocations.
184 */
185 void *ptr = kmalloc_node(size, kmalloc_lflags, NUMA_NO_NODE);
186 if (ptr || size <= PAGE_SIZE ||
187 (lflags & __GFP_RECLAIM) != __GFP_RECLAIM) {
188 return (ptr);
189 }
190
191 /*
192 * vmalloc fallback. KM_VMEM may not have been requested originally if
193 * we've come through spl_kmem_alloc_impl(), so we need to remove
194 * __GFP_COMP, which is not a valid flag for vmalloc.
195 */
196 lflags &= ~__GFP_COMP;
197 return (spl_vmalloc(size, lflags));
198 }
199
200 /*
201 * General purpose unified implementation of kmem_alloc(). It is an
202 * amalgamation of Linux and Illumos allocator design. It should never be
203 * exported to ensure that code using kmem_alloc()/kmem_zalloc() remains
204 * relatively portable. Consumers may only access this function through
205 * wrappers that enforce the common flags to ensure portability.
206 */
207 inline void *
spl_kmem_alloc_impl(size_t size,int flags,int node)208 spl_kmem_alloc_impl(size_t size, int flags, int node)
209 {
210 gfp_t lflags = kmem_flags_convert(flags);
211 void *ptr;
212
213 /*
214 * Log abnormally large allocations and rate limit the console output.
215 * Allocations larger than spl_kmem_alloc_warn should be performed
216 * through the vmem_alloc()/vmem_zalloc() interfaces.
217 */
218 if ((spl_kmem_alloc_warn > 0) && (size > spl_kmem_alloc_warn) &&
219 !(flags & KM_VMEM)) {
220 printk(KERN_WARNING
221 "Large kmem_alloc(%lu, 0x%x), please file an issue at:\n"
222 "https://github.com/openzfs/zfs/issues/new\n",
223 (unsigned long)size, flags);
224 dump_stack();
225 }
226
227 /*
228 * Use a loop because kmalloc_node() can fail when GFP_KERNEL is used
229 * unlike kmem_alloc() with KM_SLEEP on Illumos.
230 */
231 do {
232 /*
233 * Calling kmalloc_node() when the size >= spl_kmem_alloc_max
234 * is unsafe. This must fail for all for kmem_alloc() and
235 * kmem_zalloc() callers.
236 *
237 * For vmem_alloc() and vmem_zalloc() callers it is permissible
238 * to use spl_vmalloc(). However, in general use of
239 * spl_vmalloc() is strongly discouraged because a global lock
240 * must be acquired. Contention on this lock can significantly
241 * impact performance so frequently manipulating the virtual
242 * address space is strongly discouraged.
243 */
244 if (size > spl_kmem_alloc_max) {
245 if (flags & KM_VMEM) {
246 ptr = spl_vmalloc(size, lflags);
247 } else {
248 return (NULL);
249 }
250 } else {
251 /*
252 * We use kmalloc when doing kmem_alloc(KM_NOSLEEP),
253 * because kvmalloc/vmalloc may sleep. We also use
254 * kmalloc on systems with limited kernel VA space (e.g.
255 * 32-bit), which have HIGHMEM. Otherwise we use
256 * kvmalloc, which tries to get contiguous physical
257 * memory (fast, like kmalloc) and falls back on using
258 * virtual memory to stitch together pages (slow, like
259 * vmalloc).
260 */
261 #ifdef CONFIG_HIGHMEM
262 if (flags & KM_VMEM) {
263 #else
264 if ((flags & KM_VMEM) || !(flags & KM_NOSLEEP)) {
265 #endif
266 ptr = spl_kvmalloc(size, lflags);
267 } else {
268 ptr = kmalloc_node(size, lflags, node);
269 }
270 }
271
272 if (likely(ptr) || (flags & KM_NOSLEEP))
273 return (ptr);
274
275 /*
276 * Try hard to satisfy the allocation. However, when progress
277 * cannot be made, the allocation is allowed to fail.
278 */
279 if ((lflags & GFP_KERNEL) == GFP_KERNEL)
280 lflags |= __GFP_RETRY_MAYFAIL;
281
282 /*
283 * Use cond_resched() instead of congestion_wait() to avoid
284 * deadlocking systems where there are no block devices.
285 */
286 cond_resched();
287 } while (1);
288
289 return (NULL);
290 }
291
292 inline void
293 spl_kmem_free_impl(const void *buf, size_t size)
294 {
295 if (is_vmalloc_addr(buf))
296 vfree(buf);
297 else
298 kfree(buf);
299 }
300
301 /*
302 * Memory allocation and accounting for kmem_* * style allocations. When
303 * DEBUG_KMEM is enabled the total memory allocated will be tracked and
304 * any memory leaked will be reported during module unload.
305 *
306 * ./configure --enable-debug-kmem
307 */
308 #ifdef DEBUG_KMEM
309
310 /* Shim layer memory accounting */
311 atomic64_t kmem_alloc_used = ATOMIC64_INIT(0);
312 uint64_t kmem_alloc_max = 0;
313
314 EXPORT_SYMBOL(kmem_alloc_used);
315 EXPORT_SYMBOL(kmem_alloc_max);
316
317 inline void *
318 spl_kmem_alloc_debug(size_t size, int flags, int node)
319 {
320 void *ptr;
321
322 ptr = spl_kmem_alloc_impl(size, flags, node);
323 if (ptr) {
324 atomic64_add(size, &kmem_alloc_used);
325 if (unlikely(atomic64_read(&kmem_alloc_used) > kmem_alloc_max))
326 kmem_alloc_max = atomic64_read(&kmem_alloc_used);
327 }
328
329 return (ptr);
330 }
331
332 inline void
333 spl_kmem_free_debug(const void *ptr, size_t size)
334 {
335 atomic64_sub(size, &kmem_alloc_used);
336 spl_kmem_free_impl(ptr, size);
337 }
338
339 /*
340 * When DEBUG_KMEM_TRACKING is enabled not only will total bytes be tracked
341 * but also the location of every alloc and free. When the SPL module is
342 * unloaded a list of all leaked addresses and where they were allocated
343 * will be dumped to the console. Enabling this feature has a significant
344 * impact on performance but it makes finding memory leaks straight forward.
345 *
346 * Not surprisingly with debugging enabled the xmem_locks are very highly
347 * contended particularly on xfree(). If we want to run with this detailed
348 * debugging enabled for anything other than debugging we need to minimize
349 * the contention by moving to a lock per xmem_table entry model.
350 *
351 * ./configure --enable-debug-kmem-tracking
352 */
353 #ifdef DEBUG_KMEM_TRACKING
354
355 #include <linux/hash.h>
356 #include <linux/ctype.h>
357
358 #define KMEM_HASH_BITS 10
359 #define KMEM_TABLE_SIZE (1 << KMEM_HASH_BITS)
360
361 typedef struct kmem_debug {
362 struct hlist_node kd_hlist; /* Hash node linkage */
363 struct list_head kd_list; /* List of all allocations */
364 void *kd_addr; /* Allocation pointer */
365 size_t kd_size; /* Allocation size */
366 const char *kd_func; /* Allocation function */
367 int kd_line; /* Allocation line */
368 } kmem_debug_t;
369
370 static spinlock_t kmem_lock;
371 static struct hlist_head kmem_table[KMEM_TABLE_SIZE];
372 static struct list_head kmem_list;
373
374 static kmem_debug_t *
375 kmem_del_init(spinlock_t *lock, struct hlist_head *table,
376 int bits, const void *addr)
377 {
378 struct hlist_head *head;
379 struct hlist_node *node = NULL;
380 struct kmem_debug *p;
381 unsigned long flags;
382
383 spin_lock_irqsave(lock, flags);
384
385 head = &table[hash_ptr((void *)addr, bits)];
386 hlist_for_each(node, head) {
387 p = list_entry(node, struct kmem_debug, kd_hlist);
388 if (p->kd_addr == addr) {
389 hlist_del_init(&p->kd_hlist);
390 list_del_init(&p->kd_list);
391 spin_unlock_irqrestore(lock, flags);
392 return (p);
393 }
394 }
395
396 spin_unlock_irqrestore(lock, flags);
397
398 return (NULL);
399 }
400
401 inline void *
402 spl_kmem_alloc_track(size_t size, int flags,
403 const char *func, int line, int node)
404 {
405 void *ptr = NULL;
406 kmem_debug_t *dptr;
407 unsigned long irq_flags;
408
409 dptr = kmalloc(sizeof (kmem_debug_t), kmem_flags_convert(flags));
410 if (dptr == NULL)
411 return (NULL);
412
413 dptr->kd_func = __strdup(func, flags);
414 if (dptr->kd_func == NULL) {
415 kfree(dptr);
416 return (NULL);
417 }
418
419 ptr = spl_kmem_alloc_debug(size, flags, node);
420 if (ptr == NULL) {
421 kfree(dptr->kd_func);
422 kfree(dptr);
423 return (NULL);
424 }
425
426 INIT_HLIST_NODE(&dptr->kd_hlist);
427 INIT_LIST_HEAD(&dptr->kd_list);
428
429 dptr->kd_addr = ptr;
430 dptr->kd_size = size;
431 dptr->kd_line = line;
432
433 spin_lock_irqsave(&kmem_lock, irq_flags);
434 hlist_add_head(&dptr->kd_hlist,
435 &kmem_table[hash_ptr(ptr, KMEM_HASH_BITS)]);
436 list_add_tail(&dptr->kd_list, &kmem_list);
437 spin_unlock_irqrestore(&kmem_lock, irq_flags);
438
439 return (ptr);
440 }
441
442 inline void
443 spl_kmem_free_track(const void *ptr, size_t size)
444 {
445 kmem_debug_t *dptr;
446
447 /* Ignore NULL pointer since we haven't tracked it at all */
448 if (ptr == NULL)
449 return;
450
451 /* Must exist in hash due to kmem_alloc() */
452 dptr = kmem_del_init(&kmem_lock, kmem_table, KMEM_HASH_BITS, ptr);
453 ASSERT3P(dptr, !=, NULL);
454 ASSERT3S(dptr->kd_size, ==, size);
455
456 kfree(dptr->kd_func);
457 kfree(dptr);
458
459 spl_kmem_free_debug(ptr, size);
460 }
461 #endif /* DEBUG_KMEM_TRACKING */
462 #endif /* DEBUG_KMEM */
463
464 /*
465 * Public kmem_alloc(), kmem_zalloc() and kmem_free() interfaces.
466 */
467 void *
468 spl_kmem_alloc(size_t size, int flags, const char *func, int line)
469 {
470 ASSERT0(flags & ~KM_PUBLIC_MASK);
471
472 #if !defined(DEBUG_KMEM)
473 return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
474 #elif !defined(DEBUG_KMEM_TRACKING)
475 return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
476 #else
477 return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
478 #endif
479 }
480 EXPORT_SYMBOL(spl_kmem_alloc);
481
482 void *
483 spl_kmem_zalloc(size_t size, int flags, const char *func, int line)
484 {
485 ASSERT0(flags & ~KM_PUBLIC_MASK);
486
487 flags |= KM_ZERO;
488
489 #if !defined(DEBUG_KMEM)
490 return (spl_kmem_alloc_impl(size, flags, NUMA_NO_NODE));
491 #elif !defined(DEBUG_KMEM_TRACKING)
492 return (spl_kmem_alloc_debug(size, flags, NUMA_NO_NODE));
493 #else
494 return (spl_kmem_alloc_track(size, flags, func, line, NUMA_NO_NODE));
495 #endif
496 }
497 EXPORT_SYMBOL(spl_kmem_zalloc);
498
499 void
500 spl_kmem_free(const void *buf, size_t size)
501 {
502 #if !defined(DEBUG_KMEM)
503 return (spl_kmem_free_impl(buf, size));
504 #elif !defined(DEBUG_KMEM_TRACKING)
505 return (spl_kmem_free_debug(buf, size));
506 #else
507 return (spl_kmem_free_track(buf, size));
508 #endif
509 }
510 EXPORT_SYMBOL(spl_kmem_free);
511
512 #if defined(DEBUG_KMEM) && defined(DEBUG_KMEM_TRACKING)
513 static char *
514 spl_sprintf_addr(kmem_debug_t *kd, char *str, int len, int min)
515 {
516 int size = ((len - 1) < kd->kd_size) ? (len - 1) : kd->kd_size;
517 int i, flag = 1;
518
519 ASSERT(str != NULL && len >= 17);
520 memset(str, 0, len);
521
522 /*
523 * Check for a fully printable string, and while we are at
524 * it place the printable characters in the passed buffer.
525 */
526 for (i = 0; i < size; i++) {
527 str[i] = ((char *)(kd->kd_addr))[i];
528 if (isprint(str[i])) {
529 continue;
530 } else {
531 /*
532 * Minimum number of printable characters found
533 * to make it worthwhile to print this as ascii.
534 */
535 if (i > min)
536 break;
537
538 flag = 0;
539 break;
540 }
541 }
542
543 if (!flag) {
544 sprintf(str, "%02x%02x%02x%02x%02x%02x%02x%02x",
545 *((uint8_t *)kd->kd_addr),
546 *((uint8_t *)kd->kd_addr + 2),
547 *((uint8_t *)kd->kd_addr + 4),
548 *((uint8_t *)kd->kd_addr + 6),
549 *((uint8_t *)kd->kd_addr + 8),
550 *((uint8_t *)kd->kd_addr + 10),
551 *((uint8_t *)kd->kd_addr + 12),
552 *((uint8_t *)kd->kd_addr + 14));
553 }
554
555 return (str);
556 }
557
558 static int
559 spl_kmem_init_tracking(struct list_head *list, spinlock_t *lock, int size)
560 {
561 int i;
562
563 spin_lock_init(lock);
564 INIT_LIST_HEAD(list);
565
566 for (i = 0; i < size; i++)
567 INIT_HLIST_HEAD(&kmem_table[i]);
568
569 return (0);
570 }
571
572 static void
573 spl_kmem_fini_tracking(struct list_head *list, spinlock_t *lock)
574 {
575 unsigned long flags;
576 kmem_debug_t *kd = NULL;
577 char str[17];
578
579 spin_lock_irqsave(lock, flags);
580 if (!list_empty(list))
581 printk(KERN_WARNING "%-16s %-5s %-16s %s:%s\n", "address",
582 "size", "data", "func", "line");
583
584 list_for_each_entry(kd, list, kd_list) {
585 printk(KERN_WARNING "%p %-5d %-16s %s:%d\n", kd->kd_addr,
586 (int)kd->kd_size, spl_sprintf_addr(kd, str, 17, 8),
587 kd->kd_func, kd->kd_line);
588 }
589
590 spin_unlock_irqrestore(lock, flags);
591 }
592 #endif /* DEBUG_KMEM && DEBUG_KMEM_TRACKING */
593
594 int
595 spl_kmem_init(void)
596 {
597
598 #ifdef DEBUG_KMEM
599 atomic64_set(&kmem_alloc_used, 0);
600
601
602
603 #ifdef DEBUG_KMEM_TRACKING
604 spl_kmem_init_tracking(&kmem_list, &kmem_lock, KMEM_TABLE_SIZE);
605 #endif /* DEBUG_KMEM_TRACKING */
606 #endif /* DEBUG_KMEM */
607
608 return (0);
609 }
610
611 void
612 spl_kmem_fini(void)
613 {
614 #ifdef DEBUG_KMEM
615 /*
616 * Display all unreclaimed memory addresses, including the
617 * allocation size and the first few bytes of what's located
618 * at that address to aid in debugging. Performance is not
619 * a serious concern here since it is module unload time.
620 */
621 if (atomic64_read(&kmem_alloc_used) != 0)
622 printk(KERN_WARNING "kmem leaked %ld/%llu bytes\n",
623 (unsigned long)atomic64_read(&kmem_alloc_used),
624 kmem_alloc_max);
625
626 #ifdef DEBUG_KMEM_TRACKING
627 spl_kmem_fini_tracking(&kmem_list, &kmem_lock);
628 #endif /* DEBUG_KMEM_TRACKING */
629 #endif /* DEBUG_KMEM */
630 }
631