Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * mm/percpu.c - percpu memory allocator
4 : *
5 : * Copyright (C) 2009 SUSE Linux Products GmbH
6 : * Copyright (C) 2009 Tejun Heo <tj@kernel.org>
7 : *
8 : * Copyright (C) 2017 Facebook Inc.
9 : * Copyright (C) 2017 Dennis Zhou <dennis@kernel.org>
10 : *
11 : * The percpu allocator handles both static and dynamic areas. Percpu
12 : * areas are allocated in chunks which are divided into units. There is
13 : * a 1-to-1 mapping for units to possible cpus. These units are grouped
14 : * based on NUMA properties of the machine.
15 : *
16 : * c0 c1 c2
17 : * ------------------- ------------------- ------------
18 : * | u0 | u1 | u2 | u3 | | u0 | u1 | u2 | u3 | | u0 | u1 | u
19 : * ------------------- ...... ------------------- .... ------------
20 : *
21 : * Allocation is done by offsets into a unit's address space. Ie., an
22 : * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
23 : * c1:u1, c1:u2, etc. On NUMA machines, the mapping may be non-linear
24 : * and even sparse. Access is handled by configuring percpu base
25 : * registers according to the cpu to unit mappings and offsetting the
26 : * base address using pcpu_unit_size.
27 : *
28 : * There is special consideration for the first chunk which must handle
29 : * the static percpu variables in the kernel image as allocation services
30 : * are not online yet. In short, the first chunk is structured like so:
31 : *
32 : * <Static | [Reserved] | Dynamic>
33 : *
34 : * The static data is copied from the original section managed by the
35 : * linker. The reserved section, if non-zero, primarily manages static
36 : * percpu variables from kernel modules. Finally, the dynamic section
37 : * takes care of normal allocations.
38 : *
39 : * The allocator organizes chunks into lists according to free size and
40 : * memcg-awareness. To make a percpu allocation memcg-aware the __GFP_ACCOUNT
41 : * flag should be passed. All memcg-aware allocations are sharing one set
42 : * of chunks and all unaccounted allocations and allocations performed
43 : * by processes belonging to the root memory cgroup are using the second set.
44 : *
45 : * The allocator tries to allocate from the fullest chunk first. Each chunk
46 : * is managed by a bitmap with metadata blocks. The allocation map is updated
47 : * on every allocation and free to reflect the current state while the boundary
48 : * map is only updated on allocation. Each metadata block contains
49 : * information to help mitigate the need to iterate over large portions
50 : * of the bitmap. The reverse mapping from page to chunk is stored in
51 : * the page's index. Lastly, units are lazily backed and grow in unison.
52 : *
53 : * There is a unique conversion that goes on here between bytes and bits.
54 : * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE. The chunk
55 : * tracks the number of pages it is responsible for in nr_pages. Helper
56 : * functions are used to convert from between the bytes, bits, and blocks.
57 : * All hints are managed in bits unless explicitly stated.
58 : *
59 : * To use this allocator, arch code should do the following:
60 : *
61 : * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
62 : * regular address to percpu pointer and back if they need to be
63 : * different from the default
64 : *
65 : * - use pcpu_setup_first_chunk() during percpu area initialization to
66 : * setup the first chunk containing the kernel static percpu area
67 : */
68 :
69 : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
70 :
71 : #include <linux/bitmap.h>
72 : #include <linux/cpumask.h>
73 : #include <linux/memblock.h>
74 : #include <linux/err.h>
75 : #include <linux/lcm.h>
76 : #include <linux/list.h>
77 : #include <linux/log2.h>
78 : #include <linux/mm.h>
79 : #include <linux/module.h>
80 : #include <linux/mutex.h>
81 : #include <linux/percpu.h>
82 : #include <linux/pfn.h>
83 : #include <linux/slab.h>
84 : #include <linux/spinlock.h>
85 : #include <linux/vmalloc.h>
86 : #include <linux/workqueue.h>
87 : #include <linux/kmemleak.h>
88 : #include <linux/sched.h>
89 : #include <linux/sched/mm.h>
90 : #include <linux/memcontrol.h>
91 :
92 : #include <asm/cacheflush.h>
93 : #include <asm/sections.h>
94 : #include <asm/tlbflush.h>
95 : #include <asm/io.h>
96 :
97 : #define CREATE_TRACE_POINTS
98 : #include <trace/events/percpu.h>
99 :
100 : #include "percpu-internal.h"
101 :
102 : /* the slots are sorted by free bytes left, 1-31 bytes share the same slot */
103 : #define PCPU_SLOT_BASE_SHIFT 5
104 : /* chunks in slots below this are subject to being sidelined on failed alloc */
105 : #define PCPU_SLOT_FAIL_THRESHOLD 3
106 :
107 : #define PCPU_EMPTY_POP_PAGES_LOW 2
108 : #define PCPU_EMPTY_POP_PAGES_HIGH 4
109 :
110 : #ifdef CONFIG_SMP
111 : /* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
112 : #ifndef __addr_to_pcpu_ptr
113 : #define __addr_to_pcpu_ptr(addr) \
114 : (void __percpu *)((unsigned long)(addr) - \
115 : (unsigned long)pcpu_base_addr + \
116 : (unsigned long)__per_cpu_start)
117 : #endif
118 : #ifndef __pcpu_ptr_to_addr
119 : #define __pcpu_ptr_to_addr(ptr) \
120 : (void __force *)((unsigned long)(ptr) + \
121 : (unsigned long)pcpu_base_addr - \
122 : (unsigned long)__per_cpu_start)
123 : #endif
124 : #else /* CONFIG_SMP */
125 : /* on UP, it's always identity mapped */
126 : #define __addr_to_pcpu_ptr(addr) (void __percpu *)(addr)
127 : #define __pcpu_ptr_to_addr(ptr) (void __force *)(ptr)
128 : #endif /* CONFIG_SMP */
129 :
130 : static int pcpu_unit_pages __ro_after_init;
131 : static int pcpu_unit_size __ro_after_init;
132 : static int pcpu_nr_units __ro_after_init;
133 : static int pcpu_atom_size __ro_after_init;
134 : int pcpu_nr_slots __ro_after_init;
135 : static size_t pcpu_chunk_struct_size __ro_after_init;
136 :
137 : /* cpus with the lowest and highest unit addresses */
138 : static unsigned int pcpu_low_unit_cpu __ro_after_init;
139 : static unsigned int pcpu_high_unit_cpu __ro_after_init;
140 :
141 : /* the address of the first chunk which starts with the kernel static area */
142 : void *pcpu_base_addr __ro_after_init;
143 : EXPORT_SYMBOL_GPL(pcpu_base_addr);
144 :
145 : static const int *pcpu_unit_map __ro_after_init; /* cpu -> unit */
146 : const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
147 :
148 : /* group information, used for vm allocation */
149 : static int pcpu_nr_groups __ro_after_init;
150 : static const unsigned long *pcpu_group_offsets __ro_after_init;
151 : static const size_t *pcpu_group_sizes __ro_after_init;
152 :
153 : /*
154 : * The first chunk which always exists. Note that unlike other
155 : * chunks, this one can be allocated and mapped in several different
156 : * ways and thus often doesn't live in the vmalloc area.
157 : */
158 : struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
159 :
160 : /*
161 : * Optional reserved chunk. This chunk reserves part of the first
162 : * chunk and serves it for reserved allocations. When the reserved
163 : * region doesn't exist, the following variable is NULL.
164 : */
165 : struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
166 :
167 : DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
168 : static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */
169 :
170 : struct list_head *pcpu_chunk_lists __ro_after_init; /* chunk list slots */
171 :
172 : /* chunks which need their map areas extended, protected by pcpu_lock */
173 : static LIST_HEAD(pcpu_map_extend_chunks);
174 :
175 : /*
176 : * The number of empty populated pages, protected by pcpu_lock. The
177 : * reserved chunk doesn't contribute to the count.
178 : */
179 : int pcpu_nr_empty_pop_pages;
180 :
181 : /*
182 : * The number of populated pages in use by the allocator, protected by
183 : * pcpu_lock. This number is kept per a unit per chunk (i.e. when a page gets
184 : * allocated/deallocated, it is allocated/deallocated in all units of a chunk
185 : * and increments/decrements this count by 1).
186 : */
187 : static unsigned long pcpu_nr_populated;
188 :
189 : /*
190 : * Balance work is used to populate or destroy chunks asynchronously. We
191 : * try to keep the number of populated free pages between
192 : * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
193 : * empty chunk.
194 : */
195 : static void pcpu_balance_workfn(struct work_struct *work);
196 : static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
197 : static bool pcpu_async_enabled __read_mostly;
198 : static bool pcpu_atomic_alloc_failed;
199 :
200 4 : static void pcpu_schedule_balance_work(void)
201 : {
202 4 : if (pcpu_async_enabled)
203 4 : schedule_work(&pcpu_balance_work);
204 4 : }
205 :
206 : /**
207 : * pcpu_addr_in_chunk - check if the address is served from this chunk
208 : * @chunk: chunk of interest
209 : * @addr: percpu address
210 : *
211 : * RETURNS:
212 : * True if the address is served from this chunk.
213 : */
214 1685 : static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
215 : {
216 1685 : void *start_addr, *end_addr;
217 :
218 1685 : if (!chunk)
219 : return false;
220 :
221 1558 : start_addr = chunk->base_addr + chunk->start_offset;
222 1558 : end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
223 1558 : chunk->end_offset;
224 :
225 1558 : return addr >= start_addr && addr < end_addr;
226 : }
227 :
228 9635 : static int __pcpu_size_to_slot(int size)
229 : {
230 9635 : int highbit = fls(size); /* size is in bytes */
231 9634 : return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
232 : }
233 :
234 9636 : static int pcpu_size_to_slot(int size)
235 : {
236 9636 : if (size == pcpu_unit_size)
237 2 : return pcpu_nr_slots - 1;
238 9634 : return __pcpu_size_to_slot(size);
239 : }
240 :
241 7462 : static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
242 : {
243 7462 : const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
244 :
245 7462 : if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
246 7462 : chunk_md->contig_hint == 0)
247 : return 0;
248 :
249 7462 : return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
250 : }
251 :
252 : /* set the pointer to a chunk in a page struct */
253 12 : static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
254 : {
255 12 : page->index = (unsigned long)pcpu;
256 : }
257 :
258 : /* obtain pointer to a chunk from a page struct */
259 127 : static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
260 : {
261 127 : return (struct pcpu_chunk *)page->index;
262 : }
263 :
264 28 : static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
265 : {
266 28 : return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
267 : }
268 :
269 8756 : static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
270 : {
271 8756 : return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
272 : }
273 :
274 8692 : static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
275 : unsigned int cpu, int page_idx)
276 : {
277 8692 : return (unsigned long)chunk->base_addr +
278 4 : pcpu_unit_page_offset(cpu, page_idx);
279 : }
280 :
281 : /*
282 : * The following are helper functions to help access bitmaps and convert
283 : * between bitmap offsets to address offsets.
284 : */
285 5181 : static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
286 : {
287 5181 : return chunk->alloc_map +
288 5181 : (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
289 : }
290 :
291 7002 : static unsigned long pcpu_off_to_block_index(int off)
292 : {
293 7002 : return off / PCPU_BITMAP_BLOCK_BITS;
294 : }
295 :
296 7002 : static unsigned long pcpu_off_to_block_off(int off)
297 : {
298 7002 : return off & (PCPU_BITMAP_BLOCK_BITS - 1);
299 : }
300 :
301 4024 : static unsigned long pcpu_block_off_to_off(int index, int off)
302 : {
303 4024 : return index * PCPU_BITMAP_BLOCK_BITS + off;
304 : }
305 :
306 : /*
307 : * pcpu_next_hint - determine which hint to use
308 : * @block: block of interest
309 : * @alloc_bits: size of allocation
310 : *
311 : * This determines if we should scan based on the scan_hint or first_free.
312 : * In general, we want to scan from first_free to fulfill allocations by
313 : * first fit. However, if we know a scan_hint at position scan_hint_start
314 : * cannot fulfill an allocation, we can begin scanning from there knowing
315 : * the contig_hint will be our fallback.
316 : */
317 4339 : static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
318 : {
319 : /*
320 : * The three conditions below determine if we can skip past the
321 : * scan_hint. First, does the scan hint exist. Second, is the
322 : * contig_hint after the scan_hint (possibly not true iff
323 : * contig_hint == scan_hint). Third, is the allocation request
324 : * larger than the scan_hint.
325 : */
326 6089 : if (block->scan_hint &&
327 1750 : block->contig_hint_start > block->scan_hint_start &&
328 : alloc_bits > block->scan_hint)
329 843 : return block->scan_hint_start + block->scan_hint;
330 :
331 3496 : return block->first_free;
332 : }
333 :
334 : /**
335 : * pcpu_next_md_free_region - finds the next hint free area
336 : * @chunk: chunk of interest
337 : * @bit_off: chunk offset
338 : * @bits: size of free area
339 : *
340 : * Helper function for pcpu_for_each_md_free_region. It checks
341 : * block->contig_hint and performs aggregation across blocks to find the
342 : * next hint. It modifies bit_off and bits in-place to be consumed in the
343 : * loop.
344 : */
345 824 : static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
346 : int *bits)
347 : {
348 824 : int i = pcpu_off_to_block_index(*bit_off);
349 824 : int block_off = pcpu_off_to_block_off(*bit_off);
350 824 : struct pcpu_block_md *block;
351 :
352 824 : *bits = 0;
353 10434 : for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
354 9610 : block++, i++) {
355 : /* handles contig area across blocks */
356 9639 : if (*bits) {
357 9000 : *bits += block->left_free;
358 9000 : if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
359 9000 : continue;
360 : return;
361 : }
362 :
363 : /*
364 : * This checks three things. First is there a contig_hint to
365 : * check. Second, have we checked this hint before by
366 : * comparing the block_off. Third, is this the same as the
367 : * right contig hint. In the last case, it spills over into
368 : * the next block and should be handled by the contig area
369 : * across blocks code.
370 : */
371 639 : *bits = block->contig_hint;
372 639 : if (*bits && block->contig_hint_start >= block_off &&
373 426 : *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
374 29 : *bit_off = pcpu_block_off_to_off(i,
375 : block->contig_hint_start);
376 29 : return;
377 : }
378 : /* reset to satisfy the second predicate above */
379 610 : block_off = 0;
380 :
381 610 : *bits = block->right_free;
382 610 : *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
383 : }
384 : }
385 :
386 : /**
387 : * pcpu_next_fit_region - finds fit areas for a given allocation request
388 : * @chunk: chunk of interest
389 : * @alloc_bits: size of allocation
390 : * @align: alignment of area (max PAGE_SIZE)
391 : * @bit_off: chunk offset
392 : * @bits: size of free area
393 : *
394 : * Finds the next free region that is viable for use with a given size and
395 : * alignment. This only returns if there is a valid area to be used for this
396 : * allocation. block->first_free is returned if the allocation request fits
397 : * within the block to see if the request can be fulfilled prior to the contig
398 : * hint.
399 : */
400 2172 : static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
401 : int align, int *bit_off, int *bits)
402 : {
403 2172 : int i = pcpu_off_to_block_index(*bit_off);
404 2172 : int block_off = pcpu_off_to_block_off(*bit_off);
405 2172 : struct pcpu_block_md *block;
406 :
407 2172 : *bits = 0;
408 2442 : for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
409 270 : block++, i++) {
410 : /* handles contig area across blocks */
411 2442 : if (*bits) {
412 5 : *bits += block->left_free;
413 5 : if (*bits >= alloc_bits)
414 : return;
415 0 : if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
416 0 : continue;
417 : }
418 :
419 : /* check block->contig_hint */
420 2437 : *bits = ALIGN(block->contig_hint_start, align) -
421 : block->contig_hint_start;
422 : /*
423 : * This uses the block offset to determine if this has been
424 : * checked in the prior iteration.
425 : */
426 2437 : if (block->contig_hint &&
427 2379 : block->contig_hint_start >= block_off &&
428 2273 : block->contig_hint >= *bits + alloc_bits) {
429 2167 : int start = pcpu_next_hint(block, alloc_bits);
430 :
431 2167 : *bits += alloc_bits + block->contig_hint_start -
432 : start;
433 2167 : *bit_off = pcpu_block_off_to_off(i, start);
434 2167 : return;
435 : }
436 : /* reset to satisfy the second predicate above */
437 270 : block_off = 0;
438 :
439 270 : *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
440 : align);
441 270 : *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
442 270 : *bit_off = pcpu_block_off_to_off(i, *bit_off);
443 270 : if (*bits >= alloc_bits)
444 : return;
445 : }
446 :
447 : /* no valid offsets were found - fail condition */
448 0 : *bit_off = pcpu_chunk_map_bits(chunk);
449 : }
450 :
451 : /*
452 : * Metadata free area iterators. These perform aggregation of free areas
453 : * based on the metadata blocks and return the offset @bit_off and size in
454 : * bits of the free area @bits. pcpu_for_each_fit_region only returns when
455 : * a fit is found for the allocation request.
456 : */
457 : #define pcpu_for_each_md_free_region(chunk, bit_off, bits) \
458 : for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits)); \
459 : (bit_off) < pcpu_chunk_map_bits((chunk)); \
460 : (bit_off) += (bits) + 1, \
461 : pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
462 :
463 : #define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) \
464 : for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
465 : &(bits)); \
466 : (bit_off) < pcpu_chunk_map_bits((chunk)); \
467 : (bit_off) += (bits), \
468 : pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
469 : &(bits)))
470 :
471 : /**
472 : * pcpu_mem_zalloc - allocate memory
473 : * @size: bytes to allocate
474 : * @gfp: allocation flags
475 : *
476 : * Allocate @size bytes. If @size is smaller than PAGE_SIZE,
477 : * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
478 : * This is to facilitate passing through whitelisted flags. The
479 : * returned memory is always zeroed.
480 : *
481 : * RETURNS:
482 : * Pointer to the allocated area on success, NULL on failure.
483 : */
484 5 : static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
485 : {
486 5 : if (WARN_ON_ONCE(!slab_is_available()))
487 : return NULL;
488 :
489 5 : if (size <= PAGE_SIZE)
490 3 : return kzalloc(size, gfp);
491 : else
492 2 : return __vmalloc(size, gfp | __GFP_ZERO);
493 : }
494 :
495 : /**
496 : * pcpu_mem_free - free memory
497 : * @ptr: memory to free
498 : *
499 : * Free @ptr. @ptr should have been allocated using pcpu_mem_zalloc().
500 : */
501 0 : static void pcpu_mem_free(void *ptr)
502 : {
503 0 : kvfree(ptr);
504 0 : }
505 :
506 15 : static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
507 : bool move_front)
508 : {
509 15 : if (chunk != pcpu_reserved_chunk) {
510 15 : struct list_head *pcpu_slot;
511 :
512 15 : pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
513 15 : if (move_front)
514 3 : list_move(&chunk->list, &pcpu_slot[slot]);
515 : else
516 12 : list_move_tail(&chunk->list, &pcpu_slot[slot]);
517 : }
518 15 : }
519 :
520 1 : static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
521 : {
522 1 : __pcpu_chunk_move(chunk, slot, true);
523 1 : }
524 :
525 : /**
526 : * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
527 : * @chunk: chunk of interest
528 : * @oslot: the previous slot it was on
529 : *
530 : * This function is called after an allocation or free changed @chunk.
531 : * New slot according to the changed state is determined and @chunk is
532 : * moved to the slot. Note that the reserved chunk is never put on
533 : * chunk slots.
534 : *
535 : * CONTEXT:
536 : * pcpu_lock.
537 : */
538 3732 : static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
539 : {
540 3732 : int nslot = pcpu_chunk_slot(chunk);
541 :
542 3732 : if (oslot != nslot)
543 14 : __pcpu_chunk_move(chunk, nslot, oslot < nslot);
544 3732 : }
545 :
546 : /*
547 : * pcpu_update_empty_pages - update empty page counters
548 : * @chunk: chunk of interest
549 : * @nr: nr of empty pages
550 : *
551 : * This is used to keep track of the empty pages now based on the premise
552 : * a md_block covers a page. The hint update functions recognize if a block
553 : * is made full or broken to calculate deltas for keeping track of free pages.
554 : */
555 10 : static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
556 : {
557 10 : chunk->nr_empty_pop_pages += nr;
558 10 : if (chunk != pcpu_reserved_chunk)
559 10 : pcpu_nr_empty_pop_pages += nr;
560 : }
561 :
562 : /*
563 : * pcpu_region_overlap - determines if two regions overlap
564 : * @a: start of first region, inclusive
565 : * @b: end of first region, exclusive
566 : * @x: start of second region, inclusive
567 : * @y: end of second region, exclusive
568 : *
569 : * This is used to determine if the hint region [a, b) overlaps with the
570 : * allocated region [x, y).
571 : */
572 8692 : static inline bool pcpu_region_overlap(int a, int b, int x, int y)
573 : {
574 8692 : return (a < y) && (x < b);
575 : }
576 :
577 : /**
578 : * pcpu_block_update - updates a block given a free area
579 : * @block: block of interest
580 : * @start: start offset in block
581 : * @end: end offset in block
582 : *
583 : * Updates a block given a known free area. The region [start, end) is
584 : * expected to be the entirety of the free area within a block. Chooses
585 : * the best starting offset if the contig hints are equal.
586 : */
587 5107 : static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
588 : {
589 5107 : int contig = end - start;
590 :
591 5107 : block->first_free = min(block->first_free, start);
592 5107 : if (start == 0)
593 2 : block->left_free = contig;
594 :
595 5107 : if (end == block->nr_bits)
596 1198 : block->right_free = contig;
597 :
598 5107 : if (contig > block->contig_hint) {
599 : /* promote the old contig_hint to be the new scan_hint */
600 1296 : if (start > block->contig_hint_start) {
601 1118 : if (block->contig_hint > block->scan_hint) {
602 409 : block->scan_hint_start =
603 : block->contig_hint_start;
604 409 : block->scan_hint = block->contig_hint;
605 709 : } else if (start < block->scan_hint_start) {
606 : /*
607 : * The old contig_hint == scan_hint. But, the
608 : * new contig is larger so hold the invariant
609 : * scan_hint_start < contig_hint_start.
610 : */
611 9 : block->scan_hint = 0;
612 : }
613 : } else {
614 178 : block->scan_hint = 0;
615 : }
616 1296 : block->contig_hint_start = start;
617 1296 : block->contig_hint = contig;
618 3811 : } else if (contig == block->contig_hint) {
619 312 : if (block->contig_hint_start &&
620 312 : (!start ||
621 312 : __ffs(start) > __ffs(block->contig_hint_start))) {
622 : /* start has a better alignment so use it */
623 6 : block->contig_hint_start = start;
624 6 : if (start < block->scan_hint_start &&
625 1 : block->contig_hint > block->scan_hint)
626 1 : block->scan_hint = 0;
627 306 : } else if (start > block->scan_hint_start ||
628 13 : block->contig_hint > block->scan_hint) {
629 : /*
630 : * Knowing contig == contig_hint, update the scan_hint
631 : * if it is farther than or larger than the current
632 : * scan_hint.
633 : */
634 306 : block->scan_hint_start = start;
635 306 : block->scan_hint = contig;
636 : }
637 : } else {
638 : /*
639 : * The region is smaller than the contig_hint. So only update
640 : * the scan_hint if it is larger than or equal and farther than
641 : * the current scan_hint.
642 : */
643 3499 : if ((start < block->contig_hint_start &&
644 3033 : (contig > block->scan_hint ||
645 186 : (contig == block->scan_hint &&
646 186 : start > block->scan_hint_start)))) {
647 886 : block->scan_hint_start = start;
648 886 : block->scan_hint = contig;
649 : }
650 : }
651 5107 : }
652 :
653 : /*
654 : * pcpu_block_update_scan - update a block given a free area from a scan
655 : * @chunk: chunk of interest
656 : * @bit_off: chunk offset
657 : * @bits: size of free area
658 : *
659 : * Finding the final allocation spot first goes through pcpu_find_block_fit()
660 : * to find a block that can hold the allocation and then pcpu_alloc_area()
661 : * where a scan is used. When allocations require specific alignments,
662 : * we can inadvertently create holes which will not be seen in the alloc
663 : * or free paths.
664 : *
665 : * This takes a given free area hole and updates a block as it may change the
666 : * scan_hint. We need to scan backwards to ensure we don't miss free bits
667 : * from alignment.
668 : */
669 275 : static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
670 : int bits)
671 : {
672 275 : int s_off = pcpu_off_to_block_off(bit_off);
673 275 : int e_off = s_off + bits;
674 275 : int s_index, l_bit;
675 275 : struct pcpu_block_md *block;
676 :
677 275 : if (e_off > PCPU_BITMAP_BLOCK_BITS)
678 : return;
679 :
680 275 : s_index = pcpu_off_to_block_index(bit_off);
681 275 : block = chunk->md_blocks + s_index;
682 :
683 : /* scan backwards in case of alignment skipping free bits */
684 275 : l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
685 275 : s_off = (s_off == l_bit) ? 0 : l_bit + 1;
686 :
687 275 : pcpu_block_update(block, s_off, e_off);
688 : }
689 :
690 : /**
691 : * pcpu_chunk_refresh_hint - updates metadata about a chunk
692 : * @chunk: chunk of interest
693 : * @full_scan: if we should scan from the beginning
694 : *
695 : * Iterates over the metadata blocks to find the largest contig area.
696 : * A full scan can be avoided on the allocation path as this is triggered
697 : * if we broke the contig_hint. In doing so, the scan_hint will be before
698 : * the contig_hint or after if the scan_hint == contig_hint. This cannot
699 : * be prevented on freeing as we want to find the largest area possibly
700 : * spanning blocks.
701 : */
702 398 : static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
703 : {
704 398 : struct pcpu_block_md *chunk_md = &chunk->chunk_md;
705 398 : int bit_off, bits;
706 :
707 : /* promote scan_hint to contig_hint */
708 398 : if (!full_scan && chunk_md->scan_hint) {
709 150 : bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
710 150 : chunk_md->contig_hint_start = chunk_md->scan_hint_start;
711 150 : chunk_md->contig_hint = chunk_md->scan_hint;
712 150 : chunk_md->scan_hint = 0;
713 : } else {
714 248 : bit_off = chunk_md->first_free;
715 248 : chunk_md->contig_hint = 0;
716 : }
717 :
718 398 : bits = 0;
719 824 : pcpu_for_each_md_free_region(chunk, bit_off, bits)
720 426 : pcpu_block_update(chunk_md, bit_off, bit_off + bits);
721 398 : }
722 :
723 : /**
724 : * pcpu_block_refresh_hint
725 : * @chunk: chunk of interest
726 : * @index: index of the metadata block
727 : *
728 : * Scans over the block beginning at first_free and updates the block
729 : * metadata accordingly.
730 : */
731 741 : static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
732 : {
733 741 : struct pcpu_block_md *block = chunk->md_blocks + index;
734 741 : unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
735 741 : unsigned int rs, re, start; /* region start, region end */
736 :
737 : /* promote scan_hint to contig_hint */
738 741 : if (block->scan_hint) {
739 374 : start = block->scan_hint_start + block->scan_hint;
740 374 : block->contig_hint_start = block->scan_hint_start;
741 374 : block->contig_hint = block->scan_hint;
742 374 : block->scan_hint = 0;
743 : } else {
744 367 : start = block->first_free;
745 367 : block->contig_hint = 0;
746 : }
747 :
748 741 : block->right_free = 0;
749 :
750 : /* iterate over free areas and update the contig hints */
751 2031 : bitmap_for_each_clear_region(alloc_map, rs, re, start,
752 : PCPU_BITMAP_BLOCK_BITS)
753 1290 : pcpu_block_update(block, rs, re);
754 741 : }
755 :
756 : /**
757 : * pcpu_block_update_hint_alloc - update hint on allocation path
758 : * @chunk: chunk of interest
759 : * @bit_off: chunk offset
760 : * @bits: size of request
761 : *
762 : * Updates metadata for the allocation path. The metadata only has to be
763 : * refreshed by a full scan iff the chunk's contig hint is broken. Block level
764 : * scans are required if the block's contig hint is broken.
765 : */
766 2173 : static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
767 : int bits)
768 : {
769 2173 : struct pcpu_block_md *chunk_md = &chunk->chunk_md;
770 2173 : int nr_empty_pages = 0;
771 2173 : struct pcpu_block_md *s_block, *e_block, *block;
772 2173 : int s_index, e_index; /* block indexes of the freed allocation */
773 2173 : int s_off, e_off; /* block offsets of the freed allocation */
774 :
775 : /*
776 : * Calculate per block offsets.
777 : * The calculation uses an inclusive range, but the resulting offsets
778 : * are [start, end). e_index always points to the last block in the
779 : * range.
780 : */
781 2173 : s_index = pcpu_off_to_block_index(bit_off);
782 2173 : e_index = pcpu_off_to_block_index(bit_off + bits - 1);
783 2173 : s_off = pcpu_off_to_block_off(bit_off);
784 2173 : e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
785 :
786 2173 : s_block = chunk->md_blocks + s_index;
787 2173 : e_block = chunk->md_blocks + e_index;
788 :
789 : /*
790 : * Update s_block.
791 : * block->first_free must be updated if the allocation takes its place.
792 : * If the allocation breaks the contig_hint, a scan is required to
793 : * restore this hint.
794 : */
795 2173 : if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
796 4 : nr_empty_pages++;
797 :
798 2173 : if (s_off == s_block->first_free)
799 1175 : s_block->first_free = find_next_zero_bit(
800 1175 : pcpu_index_alloc_map(chunk, s_index),
801 : PCPU_BITMAP_BLOCK_BITS,
802 1175 : s_off + bits);
803 :
804 2173 : if (pcpu_region_overlap(s_block->scan_hint_start,
805 2173 : s_block->scan_hint_start + s_block->scan_hint,
806 : s_off,
807 : s_off + bits))
808 140 : s_block->scan_hint = 0;
809 :
810 2173 : if (pcpu_region_overlap(s_block->contig_hint_start,
811 2173 : s_block->contig_hint_start +
812 2173 : s_block->contig_hint,
813 : s_off,
814 : s_off + bits)) {
815 : /* block contig hint is broken - scan to fix it */
816 736 : if (!s_off)
817 4 : s_block->left_free = 0;
818 736 : pcpu_block_refresh_hint(chunk, s_index);
819 : } else {
820 : /* update left and right contig manually */
821 1437 : s_block->left_free = min(s_block->left_free, s_off);
822 1437 : if (s_index == e_index)
823 1437 : s_block->right_free = min_t(int, s_block->right_free,
824 : PCPU_BITMAP_BLOCK_BITS - e_off);
825 : else
826 0 : s_block->right_free = 0;
827 : }
828 :
829 : /*
830 : * Update e_block.
831 : */
832 2173 : if (s_index != e_index) {
833 5 : if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
834 5 : nr_empty_pages++;
835 :
836 : /*
837 : * When the allocation is across blocks, the end is along
838 : * the left part of the e_block.
839 : */
840 10 : e_block->first_free = find_next_zero_bit(
841 5 : pcpu_index_alloc_map(chunk, e_index),
842 : PCPU_BITMAP_BLOCK_BITS, e_off);
843 :
844 5 : if (e_off == PCPU_BITMAP_BLOCK_BITS) {
845 : /* reset the block */
846 0 : e_block++;
847 : } else {
848 5 : if (e_off > e_block->scan_hint_start)
849 5 : e_block->scan_hint = 0;
850 :
851 5 : e_block->left_free = 0;
852 5 : if (e_off > e_block->contig_hint_start) {
853 : /* contig hint is broken - scan to fix it */
854 5 : pcpu_block_refresh_hint(chunk, e_index);
855 : } else {
856 0 : e_block->right_free =
857 0 : min_t(int, e_block->right_free,
858 : PCPU_BITMAP_BLOCK_BITS - e_off);
859 : }
860 : }
861 :
862 : /* update in-between md_blocks */
863 5 : nr_empty_pages += (e_index - s_index - 1);
864 5 : for (block = s_block + 1; block < e_block; block++) {
865 0 : block->scan_hint = 0;
866 0 : block->contig_hint = 0;
867 0 : block->left_free = 0;
868 0 : block->right_free = 0;
869 : }
870 : }
871 :
872 2173 : if (nr_empty_pages)
873 9 : pcpu_update_empty_pages(chunk, -nr_empty_pages);
874 :
875 2173 : if (pcpu_region_overlap(chunk_md->scan_hint_start,
876 2173 : chunk_md->scan_hint_start +
877 2173 : chunk_md->scan_hint,
878 : bit_off,
879 : bit_off + bits))
880 30 : chunk_md->scan_hint = 0;
881 :
882 : /*
883 : * The only time a full chunk scan is required is if the chunk
884 : * contig hint is broken. Otherwise, it means a smaller space
885 : * was used and therefore the chunk contig hint is still correct.
886 : */
887 2173 : if (pcpu_region_overlap(chunk_md->contig_hint_start,
888 2173 : chunk_md->contig_hint_start +
889 2173 : chunk_md->contig_hint,
890 : bit_off,
891 : bit_off + bits))
892 398 : pcpu_chunk_refresh_hint(chunk, false);
893 2173 : }
894 :
895 : /**
896 : * pcpu_block_update_hint_free - updates the block hints on the free path
897 : * @chunk: chunk of interest
898 : * @bit_off: chunk offset
899 : * @bits: size of request
900 : *
901 : * Updates metadata for the allocation path. This avoids a blind block
902 : * refresh by making use of the block contig hints. If this fails, it scans
903 : * forward and backward to determine the extent of the free area. This is
904 : * capped at the boundary of blocks.
905 : *
906 : * A chunk update is triggered if a page becomes free, a block becomes free,
907 : * or the free spans across blocks. This tradeoff is to minimize iterating
908 : * over the block metadata to update chunk_md->contig_hint.
909 : * chunk_md->contig_hint may be off by up to a page, but it will never be more
910 : * than the available space. If the contig hint is contained in one block, it
911 : * will be accurate.
912 : */
913 1558 : static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
914 : int bits)
915 : {
916 1558 : int nr_empty_pages = 0;
917 1558 : struct pcpu_block_md *s_block, *e_block, *block;
918 1558 : int s_index, e_index; /* block indexes of the freed allocation */
919 1558 : int s_off, e_off; /* block offsets of the freed allocation */
920 1558 : int start, end; /* start and end of the whole free area */
921 :
922 : /*
923 : * Calculate per block offsets.
924 : * The calculation uses an inclusive range, but the resulting offsets
925 : * are [start, end). e_index always points to the last block in the
926 : * range.
927 : */
928 1558 : s_index = pcpu_off_to_block_index(bit_off);
929 1558 : e_index = pcpu_off_to_block_index(bit_off + bits - 1);
930 1558 : s_off = pcpu_off_to_block_off(bit_off);
931 1558 : e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
932 :
933 1558 : s_block = chunk->md_blocks + s_index;
934 1558 : e_block = chunk->md_blocks + e_index;
935 :
936 : /*
937 : * Check if the freed area aligns with the block->contig_hint.
938 : * If it does, then the scan to find the beginning/end of the
939 : * larger free area can be avoided.
940 : *
941 : * start and end refer to beginning and end of the free area
942 : * within each their respective blocks. This is not necessarily
943 : * the entire free area as it may span blocks past the beginning
944 : * or end of the block.
945 : */
946 1558 : start = s_off;
947 1558 : if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
948 : start = s_block->contig_hint_start;
949 : } else {
950 : /*
951 : * Scan backwards to find the extent of the free area.
952 : * find_last_bit returns the starting bit, so if the start bit
953 : * is returned, that means there was no last bit and the
954 : * remainder of the chunk is free.
955 : */
956 1540 : int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
957 : start);
958 1540 : start = (start == l_bit) ? 0 : l_bit + 1;
959 : }
960 :
961 1558 : end = e_off;
962 1558 : if (e_off == e_block->contig_hint_start)
963 113 : end = e_block->contig_hint_start + e_block->contig_hint;
964 : else
965 1445 : end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
966 : PCPU_BITMAP_BLOCK_BITS, end);
967 :
968 : /* update s_block */
969 1558 : e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
970 1558 : if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
971 0 : nr_empty_pages++;
972 1558 : pcpu_block_update(s_block, start, e_off);
973 :
974 : /* freeing in the same block */
975 1558 : if (s_index != e_index) {
976 : /* update e_block */
977 0 : if (end == PCPU_BITMAP_BLOCK_BITS)
978 0 : nr_empty_pages++;
979 0 : pcpu_block_update(e_block, 0, end);
980 :
981 : /* reset md_blocks in the middle */
982 0 : nr_empty_pages += (e_index - s_index - 1);
983 0 : for (block = s_block + 1; block < e_block; block++) {
984 0 : block->first_free = 0;
985 0 : block->scan_hint = 0;
986 0 : block->contig_hint_start = 0;
987 0 : block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
988 0 : block->left_free = PCPU_BITMAP_BLOCK_BITS;
989 0 : block->right_free = PCPU_BITMAP_BLOCK_BITS;
990 : }
991 : }
992 :
993 1558 : if (nr_empty_pages)
994 0 : pcpu_update_empty_pages(chunk, nr_empty_pages);
995 :
996 : /*
997 : * Refresh chunk metadata when the free makes a block free or spans
998 : * across blocks. The contig_hint may be off by up to a page, but if
999 : * the contig_hint is contained in a block, it will be accurate with
1000 : * the else condition below.
1001 : */
1002 1558 : if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1003 0 : pcpu_chunk_refresh_hint(chunk, true);
1004 : else
1005 1558 : pcpu_block_update(&chunk->chunk_md,
1006 1558 : pcpu_block_off_to_off(s_index, start),
1007 : end);
1008 1558 : }
1009 :
1010 : /**
1011 : * pcpu_is_populated - determines if the region is populated
1012 : * @chunk: chunk of interest
1013 : * @bit_off: chunk offset
1014 : * @bits: size of area
1015 : * @next_off: return value for the next offset to start searching
1016 : *
1017 : * For atomic allocations, check if the backing pages are populated.
1018 : *
1019 : * RETURNS:
1020 : * Bool if the backing pages are populated.
1021 : * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1022 : */
1023 0 : static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1024 : int *next_off)
1025 : {
1026 0 : unsigned int page_start, page_end, rs, re;
1027 :
1028 0 : page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1029 0 : page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1030 :
1031 0 : rs = page_start;
1032 0 : bitmap_next_clear_region(chunk->populated, &rs, &re, page_end);
1033 0 : if (rs >= page_end)
1034 : return true;
1035 :
1036 0 : *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1037 0 : return false;
1038 : }
1039 :
1040 : /**
1041 : * pcpu_find_block_fit - finds the block index to start searching
1042 : * @chunk: chunk of interest
1043 : * @alloc_bits: size of request in allocation units
1044 : * @align: alignment of area (max PAGE_SIZE bytes)
1045 : * @pop_only: use populated regions only
1046 : *
1047 : * Given a chunk and an allocation spec, find the offset to begin searching
1048 : * for a free region. This iterates over the bitmap metadata blocks to
1049 : * find an offset that will be guaranteed to fit the requirements. It is
1050 : * not quite first fit as if the allocation does not fit in the contig hint
1051 : * of a block or chunk, it is skipped. This errs on the side of caution
1052 : * to prevent excess iteration. Poor alignment can cause the allocator to
1053 : * skip over blocks and chunks that have valid free areas.
1054 : *
1055 : * RETURNS:
1056 : * The offset in the bitmap to begin searching.
1057 : * -1 if no offset is found.
1058 : */
1059 2173 : static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1060 : size_t align, bool pop_only)
1061 : {
1062 2173 : struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1063 2173 : int bit_off, bits, next_off;
1064 :
1065 : /*
1066 : * Check to see if the allocation can fit in the chunk's contig hint.
1067 : * This is an optimization to prevent scanning by assuming if it
1068 : * cannot fit in the global hint, there is memory pressure and creating
1069 : * a new chunk would happen soon.
1070 : */
1071 2173 : bit_off = ALIGN(chunk_md->contig_hint_start, align) -
1072 : chunk_md->contig_hint_start;
1073 2173 : if (bit_off + alloc_bits > chunk_md->contig_hint)
1074 : return -1;
1075 :
1076 2172 : bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1077 2172 : bits = 0;
1078 2172 : pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1079 2172 : if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1080 : &next_off))
1081 : break;
1082 :
1083 0 : bit_off = next_off;
1084 0 : bits = 0;
1085 : }
1086 :
1087 2172 : if (bit_off == pcpu_chunk_map_bits(chunk))
1088 0 : return -1;
1089 :
1090 : return bit_off;
1091 : }
1092 :
1093 : /*
1094 : * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1095 : * @map: the address to base the search on
1096 : * @size: the bitmap size in bits
1097 : * @start: the bitnumber to start searching at
1098 : * @nr: the number of zeroed bits we're looking for
1099 : * @align_mask: alignment mask for zero area
1100 : * @largest_off: offset of the largest area skipped
1101 : * @largest_bits: size of the largest area skipped
1102 : *
1103 : * The @align_mask should be one less than a power of 2.
1104 : *
1105 : * This is a modified version of bitmap_find_next_zero_area_off() to remember
1106 : * the largest area that was skipped. This is imperfect, but in general is
1107 : * good enough. The largest remembered region is the largest failed region
1108 : * seen. This does not include anything we possibly skipped due to alignment.
1109 : * pcpu_block_update_scan() does scan backwards to try and recover what was
1110 : * lost to alignment. While this can cause scanning to miss earlier possible
1111 : * free areas, smaller allocations will eventually fill those holes.
1112 : */
1113 2172 : static unsigned long pcpu_find_zero_area(unsigned long *map,
1114 : unsigned long size,
1115 : unsigned long start,
1116 : unsigned long nr,
1117 : unsigned long align_mask,
1118 : unsigned long *largest_off,
1119 : unsigned long *largest_bits)
1120 : {
1121 3085 : unsigned long index, end, i, area_off, area_bits;
1122 3085 : again:
1123 3085 : index = find_next_zero_bit(map, size, start);
1124 :
1125 : /* Align allocation */
1126 3085 : index = __ALIGN_MASK(index, align_mask);
1127 3085 : area_off = index;
1128 :
1129 3085 : end = index + nr;
1130 3085 : if (end > size)
1131 0 : return end;
1132 3085 : i = find_next_bit(map, end, index);
1133 3085 : if (i < end) {
1134 913 : area_bits = i - area_off;
1135 : /* remember largest unused area with best alignment */
1136 913 : if (area_bits > *largest_bits ||
1137 619 : (area_bits == *largest_bits && *largest_off &&
1138 284 : (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1139 338 : *largest_off = area_off;
1140 338 : *largest_bits = area_bits;
1141 : }
1142 :
1143 913 : start = i + 1;
1144 913 : goto again;
1145 : }
1146 : return index;
1147 : }
1148 :
1149 : /**
1150 : * pcpu_alloc_area - allocates an area from a pcpu_chunk
1151 : * @chunk: chunk of interest
1152 : * @alloc_bits: size of request in allocation units
1153 : * @align: alignment of area (max PAGE_SIZE)
1154 : * @start: bit_off to start searching
1155 : *
1156 : * This function takes in a @start offset to begin searching to fit an
1157 : * allocation of @alloc_bits with alignment @align. It needs to scan
1158 : * the allocation map because if it fits within the block's contig hint,
1159 : * @start will be block->first_free. This is an attempt to fill the
1160 : * allocation prior to breaking the contig hint. The allocation and
1161 : * boundary maps are updated accordingly if it confirms a valid
1162 : * free area.
1163 : *
1164 : * RETURNS:
1165 : * Allocated addr offset in @chunk on success.
1166 : * -1 if no matching area is found.
1167 : */
1168 2172 : static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1169 : size_t align, int start)
1170 : {
1171 2172 : struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1172 2172 : size_t align_mask = (align) ? (align - 1) : 0;
1173 2172 : unsigned long area_off = 0, area_bits = 0;
1174 2172 : int bit_off, end, oslot;
1175 :
1176 6516 : lockdep_assert_held(&pcpu_lock);
1177 :
1178 2172 : oslot = pcpu_chunk_slot(chunk);
1179 :
1180 : /*
1181 : * Search to find a fit.
1182 : */
1183 2172 : end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1184 : pcpu_chunk_map_bits(chunk));
1185 2172 : bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1186 : align_mask, &area_off, &area_bits);
1187 2172 : if (bit_off >= end)
1188 : return -1;
1189 :
1190 2172 : if (area_bits)
1191 275 : pcpu_block_update_scan(chunk, area_off, area_bits);
1192 :
1193 : /* update alloc map */
1194 2172 : bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1195 :
1196 : /* update boundary map */
1197 2172 : set_bit(bit_off, chunk->bound_map);
1198 2172 : bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1199 2172 : set_bit(bit_off + alloc_bits, chunk->bound_map);
1200 :
1201 2172 : chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1202 :
1203 : /* update first free bit */
1204 2172 : if (bit_off == chunk_md->first_free)
1205 1147 : chunk_md->first_free = find_next_zero_bit(
1206 1147 : chunk->alloc_map,
1207 1147 : pcpu_chunk_map_bits(chunk),
1208 : bit_off + alloc_bits);
1209 :
1210 2172 : pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1211 :
1212 2172 : pcpu_chunk_relocate(chunk, oslot);
1213 :
1214 2172 : return bit_off * PCPU_MIN_ALLOC_SIZE;
1215 : }
1216 :
1217 : /**
1218 : * pcpu_free_area - frees the corresponding offset
1219 : * @chunk: chunk of interest
1220 : * @off: addr offset into chunk
1221 : *
1222 : * This function determines the size of an allocation to free using
1223 : * the boundary bitmap and clears the allocation map.
1224 : *
1225 : * RETURNS:
1226 : * Number of freed bytes.
1227 : */
1228 1558 : static int pcpu_free_area(struct pcpu_chunk *chunk, int off)
1229 : {
1230 1558 : struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1231 1558 : int bit_off, bits, end, oslot, freed;
1232 :
1233 4674 : lockdep_assert_held(&pcpu_lock);
1234 1558 : pcpu_stats_area_dealloc(chunk);
1235 :
1236 1558 : oslot = pcpu_chunk_slot(chunk);
1237 :
1238 1558 : bit_off = off / PCPU_MIN_ALLOC_SIZE;
1239 :
1240 : /* find end index */
1241 3116 : end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1242 1558 : bit_off + 1);
1243 1558 : bits = end - bit_off;
1244 1558 : bitmap_clear(chunk->alloc_map, bit_off, bits);
1245 :
1246 1558 : freed = bits * PCPU_MIN_ALLOC_SIZE;
1247 :
1248 : /* update metadata */
1249 1558 : chunk->free_bytes += freed;
1250 :
1251 : /* update first free bit */
1252 1558 : chunk_md->first_free = min(chunk_md->first_free, bit_off);
1253 :
1254 1558 : pcpu_block_update_hint_free(chunk, bit_off, bits);
1255 :
1256 1558 : pcpu_chunk_relocate(chunk, oslot);
1257 :
1258 1558 : return freed;
1259 : }
1260 :
1261 138 : static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1262 : {
1263 138 : block->scan_hint = 0;
1264 138 : block->contig_hint = nr_bits;
1265 138 : block->left_free = nr_bits;
1266 138 : block->right_free = nr_bits;
1267 138 : block->first_free = 0;
1268 138 : block->nr_bits = nr_bits;
1269 : }
1270 :
1271 2 : static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1272 : {
1273 2 : struct pcpu_block_md *md_block;
1274 :
1275 : /* init the chunk's block */
1276 2 : pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1277 :
1278 138 : for (md_block = chunk->md_blocks;
1279 138 : md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1280 136 : md_block++)
1281 136 : pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1282 2 : }
1283 :
1284 : /**
1285 : * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1286 : * @tmp_addr: the start of the region served
1287 : * @map_size: size of the region served
1288 : *
1289 : * This is responsible for creating the chunks that serve the first chunk. The
1290 : * base_addr is page aligned down of @tmp_addr while the region end is page
1291 : * aligned up. Offsets are kept track of to determine the region served. All
1292 : * this is done to appease the bitmap allocator in avoiding partial blocks.
1293 : *
1294 : * RETURNS:
1295 : * Chunk serving the region at @tmp_addr of @map_size.
1296 : */
1297 1 : static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1298 : int map_size)
1299 : {
1300 1 : struct pcpu_chunk *chunk;
1301 1 : unsigned long aligned_addr, lcm_align;
1302 1 : int start_offset, offset_bits, region_size, region_bits;
1303 1 : size_t alloc_size;
1304 :
1305 : /* region calculations */
1306 1 : aligned_addr = tmp_addr & PAGE_MASK;
1307 :
1308 1 : start_offset = tmp_addr - aligned_addr;
1309 :
1310 : /*
1311 : * Align the end of the region with the LCM of PAGE_SIZE and
1312 : * PCPU_BITMAP_BLOCK_SIZE. One of these constants is a multiple of
1313 : * the other.
1314 : */
1315 1 : lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
1316 1 : region_size = ALIGN(start_offset + map_size, lcm_align);
1317 :
1318 : /* allocate chunk */
1319 1 : alloc_size = struct_size(chunk, populated,
1320 : BITS_TO_LONGS(region_size >> PAGE_SHIFT));
1321 1 : chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1322 1 : if (!chunk)
1323 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
1324 : alloc_size);
1325 :
1326 1 : INIT_LIST_HEAD(&chunk->list);
1327 :
1328 1 : chunk->base_addr = (void *)aligned_addr;
1329 1 : chunk->start_offset = start_offset;
1330 1 : chunk->end_offset = region_size - chunk->start_offset - map_size;
1331 :
1332 1 : chunk->nr_pages = region_size >> PAGE_SHIFT;
1333 1 : region_bits = pcpu_chunk_map_bits(chunk);
1334 :
1335 1 : alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1336 1 : chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1337 1 : if (!chunk->alloc_map)
1338 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
1339 : alloc_size);
1340 :
1341 1 : alloc_size =
1342 1 : BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1343 1 : chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1344 1 : if (!chunk->bound_map)
1345 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
1346 : alloc_size);
1347 :
1348 1 : alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1349 1 : chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1350 1 : if (!chunk->md_blocks)
1351 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
1352 : alloc_size);
1353 :
1354 : #ifdef CONFIG_MEMCG_KMEM
1355 : /* first chunk isn't memcg-aware */
1356 : chunk->obj_cgroups = NULL;
1357 : #endif
1358 1 : pcpu_init_md_blocks(chunk);
1359 :
1360 : /* manage populated page bitmap */
1361 1 : chunk->immutable = true;
1362 1 : bitmap_fill(chunk->populated, chunk->nr_pages);
1363 1 : chunk->nr_populated = chunk->nr_pages;
1364 1 : chunk->nr_empty_pop_pages = chunk->nr_pages;
1365 :
1366 1 : chunk->free_bytes = map_size;
1367 :
1368 1 : if (chunk->start_offset) {
1369 : /* hide the beginning of the bitmap */
1370 1 : offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1371 1 : bitmap_set(chunk->alloc_map, 0, offset_bits);
1372 1 : set_bit(0, chunk->bound_map);
1373 1 : set_bit(offset_bits, chunk->bound_map);
1374 :
1375 1 : chunk->chunk_md.first_free = offset_bits;
1376 :
1377 1 : pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1378 : }
1379 :
1380 1 : if (chunk->end_offset) {
1381 : /* hide the end of the bitmap */
1382 0 : offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1383 0 : bitmap_set(chunk->alloc_map,
1384 0 : pcpu_chunk_map_bits(chunk) - offset_bits,
1385 : offset_bits);
1386 0 : set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1387 0 : chunk->bound_map);
1388 0 : set_bit(region_bits, chunk->bound_map);
1389 :
1390 0 : pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1391 : - offset_bits, offset_bits);
1392 : }
1393 :
1394 1 : return chunk;
1395 : }
1396 :
1397 1 : static struct pcpu_chunk *pcpu_alloc_chunk(enum pcpu_chunk_type type, gfp_t gfp)
1398 : {
1399 1 : struct pcpu_chunk *chunk;
1400 1 : int region_bits;
1401 :
1402 1 : chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1403 1 : if (!chunk)
1404 : return NULL;
1405 :
1406 1 : INIT_LIST_HEAD(&chunk->list);
1407 1 : chunk->nr_pages = pcpu_unit_pages;
1408 1 : region_bits = pcpu_chunk_map_bits(chunk);
1409 :
1410 1 : chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1411 : sizeof(chunk->alloc_map[0]), gfp);
1412 1 : if (!chunk->alloc_map)
1413 0 : goto alloc_map_fail;
1414 :
1415 1 : chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1416 : sizeof(chunk->bound_map[0]), gfp);
1417 1 : if (!chunk->bound_map)
1418 0 : goto bound_map_fail;
1419 :
1420 1 : chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1421 : sizeof(chunk->md_blocks[0]), gfp);
1422 1 : if (!chunk->md_blocks)
1423 0 : goto md_blocks_fail;
1424 :
1425 : #ifdef CONFIG_MEMCG_KMEM
1426 : if (pcpu_is_memcg_chunk(type)) {
1427 : chunk->obj_cgroups =
1428 : pcpu_mem_zalloc(pcpu_chunk_map_bits(chunk) *
1429 : sizeof(struct obj_cgroup *), gfp);
1430 : if (!chunk->obj_cgroups)
1431 : goto objcg_fail;
1432 : }
1433 : #endif
1434 :
1435 1 : pcpu_init_md_blocks(chunk);
1436 :
1437 : /* init metadata */
1438 1 : chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1439 :
1440 1 : return chunk;
1441 :
1442 : #ifdef CONFIG_MEMCG_KMEM
1443 : objcg_fail:
1444 : pcpu_mem_free(chunk->md_blocks);
1445 : #endif
1446 0 : md_blocks_fail:
1447 0 : pcpu_mem_free(chunk->bound_map);
1448 0 : bound_map_fail:
1449 0 : pcpu_mem_free(chunk->alloc_map);
1450 0 : alloc_map_fail:
1451 0 : pcpu_mem_free(chunk);
1452 :
1453 0 : return NULL;
1454 : }
1455 :
1456 0 : static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1457 : {
1458 0 : if (!chunk)
1459 : return;
1460 : #ifdef CONFIG_MEMCG_KMEM
1461 : pcpu_mem_free(chunk->obj_cgroups);
1462 : #endif
1463 0 : pcpu_mem_free(chunk->md_blocks);
1464 0 : pcpu_mem_free(chunk->bound_map);
1465 0 : pcpu_mem_free(chunk->alloc_map);
1466 0 : pcpu_mem_free(chunk);
1467 : }
1468 :
1469 : /**
1470 : * pcpu_chunk_populated - post-population bookkeeping
1471 : * @chunk: pcpu_chunk which got populated
1472 : * @page_start: the start page
1473 : * @page_end: the end page
1474 : *
1475 : * Pages in [@page_start,@page_end) have been populated to @chunk. Update
1476 : * the bookkeeping information accordingly. Must be called after each
1477 : * successful population.
1478 : *
1479 : * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it
1480 : * is to serve an allocation in that area.
1481 : */
1482 1 : static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1483 : int page_end)
1484 : {
1485 1 : int nr = page_end - page_start;
1486 :
1487 3 : lockdep_assert_held(&pcpu_lock);
1488 :
1489 1 : bitmap_set(chunk->populated, page_start, nr);
1490 1 : chunk->nr_populated += nr;
1491 1 : pcpu_nr_populated += nr;
1492 :
1493 1 : pcpu_update_empty_pages(chunk, nr);
1494 1 : }
1495 :
1496 : /**
1497 : * pcpu_chunk_depopulated - post-depopulation bookkeeping
1498 : * @chunk: pcpu_chunk which got depopulated
1499 : * @page_start: the start page
1500 : * @page_end: the end page
1501 : *
1502 : * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1503 : * Update the bookkeeping information accordingly. Must be called after
1504 : * each successful depopulation.
1505 : */
1506 0 : static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1507 : int page_start, int page_end)
1508 : {
1509 0 : int nr = page_end - page_start;
1510 :
1511 0 : lockdep_assert_held(&pcpu_lock);
1512 :
1513 0 : bitmap_clear(chunk->populated, page_start, nr);
1514 0 : chunk->nr_populated -= nr;
1515 0 : pcpu_nr_populated -= nr;
1516 :
1517 0 : pcpu_update_empty_pages(chunk, -nr);
1518 0 : }
1519 :
1520 : /*
1521 : * Chunk management implementation.
1522 : *
1523 : * To allow different implementations, chunk alloc/free and
1524 : * [de]population are implemented in a separate file which is pulled
1525 : * into this file and compiled together. The following functions
1526 : * should be implemented.
1527 : *
1528 : * pcpu_populate_chunk - populate the specified range of a chunk
1529 : * pcpu_depopulate_chunk - depopulate the specified range of a chunk
1530 : * pcpu_create_chunk - create a new chunk
1531 : * pcpu_destroy_chunk - destroy a chunk, always preceded by full depop
1532 : * pcpu_addr_to_page - translate address to physical address
1533 : * pcpu_verify_alloc_info - check alloc_info is acceptable during init
1534 : */
1535 : static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1536 : int page_start, int page_end, gfp_t gfp);
1537 : static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1538 : int page_start, int page_end);
1539 : static struct pcpu_chunk *pcpu_create_chunk(enum pcpu_chunk_type type,
1540 : gfp_t gfp);
1541 : static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1542 : static struct page *pcpu_addr_to_page(void *addr);
1543 : static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1544 :
1545 : #ifdef CONFIG_NEED_PER_CPU_KM
1546 : #include "percpu-km.c"
1547 : #else
1548 : #include "percpu-vm.c"
1549 : #endif
1550 :
1551 : /**
1552 : * pcpu_chunk_addr_search - determine chunk containing specified address
1553 : * @addr: address for which the chunk needs to be determined.
1554 : *
1555 : * This is an internal function that handles all but static allocations.
1556 : * Static percpu address values should never be passed into the allocator.
1557 : *
1558 : * RETURNS:
1559 : * The address of the found chunk.
1560 : */
1561 1558 : static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1562 : {
1563 : /* is it in the dynamic region (first chunk)? */
1564 1558 : if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1565 : return pcpu_first_chunk;
1566 :
1567 : /* is it in the reserved region? */
1568 127 : if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1569 : return pcpu_reserved_chunk;
1570 :
1571 : /*
1572 : * The address is relative to unit0 which might be unused and
1573 : * thus unmapped. Offset the address to the unit space of the
1574 : * current processor before looking it up in the vmalloc
1575 : * space. Note that any possible cpu id can be used here, so
1576 : * there's no need to worry about preemption or cpu hotplug.
1577 : */
1578 127 : addr += pcpu_unit_offsets[raw_smp_processor_id()];
1579 127 : return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1580 : }
1581 :
1582 : #ifdef CONFIG_MEMCG_KMEM
1583 : static enum pcpu_chunk_type pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
1584 : struct obj_cgroup **objcgp)
1585 : {
1586 : struct obj_cgroup *objcg;
1587 :
1588 : if (!memcg_kmem_enabled() || !(gfp & __GFP_ACCOUNT))
1589 : return PCPU_CHUNK_ROOT;
1590 :
1591 : objcg = get_obj_cgroup_from_current();
1592 : if (!objcg)
1593 : return PCPU_CHUNK_ROOT;
1594 :
1595 : if (obj_cgroup_charge(objcg, gfp, size * num_possible_cpus())) {
1596 : obj_cgroup_put(objcg);
1597 : return PCPU_FAIL_ALLOC;
1598 : }
1599 :
1600 : *objcgp = objcg;
1601 : return PCPU_CHUNK_MEMCG;
1602 : }
1603 :
1604 : static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1605 : struct pcpu_chunk *chunk, int off,
1606 : size_t size)
1607 : {
1608 : if (!objcg)
1609 : return;
1610 :
1611 : if (chunk) {
1612 : chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;
1613 :
1614 : rcu_read_lock();
1615 : mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1616 : size * num_possible_cpus());
1617 : rcu_read_unlock();
1618 : } else {
1619 : obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1620 : obj_cgroup_put(objcg);
1621 : }
1622 : }
1623 :
1624 : static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1625 : {
1626 : struct obj_cgroup *objcg;
1627 :
1628 : if (!pcpu_is_memcg_chunk(pcpu_chunk_type(chunk)))
1629 : return;
1630 :
1631 : objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
1632 : chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = NULL;
1633 :
1634 : obj_cgroup_uncharge(objcg, size * num_possible_cpus());
1635 :
1636 : rcu_read_lock();
1637 : mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
1638 : -(size * num_possible_cpus()));
1639 : rcu_read_unlock();
1640 :
1641 : obj_cgroup_put(objcg);
1642 : }
1643 :
1644 : #else /* CONFIG_MEMCG_KMEM */
1645 : static enum pcpu_chunk_type
1646 2172 : pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp, struct obj_cgroup **objcgp)
1647 : {
1648 2172 : return PCPU_CHUNK_ROOT;
1649 : }
1650 :
1651 2172 : static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
1652 : struct pcpu_chunk *chunk, int off,
1653 : size_t size)
1654 : {
1655 2172 : }
1656 :
1657 1558 : static void pcpu_memcg_free_hook(struct pcpu_chunk *chunk, int off, size_t size)
1658 : {
1659 1558 : }
1660 : #endif /* CONFIG_MEMCG_KMEM */
1661 :
1662 : /**
1663 : * pcpu_alloc - the percpu allocator
1664 : * @size: size of area to allocate in bytes
1665 : * @align: alignment of area (max PAGE_SIZE)
1666 : * @reserved: allocate from the reserved chunk if available
1667 : * @gfp: allocation flags
1668 : *
1669 : * Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
1670 : * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1671 : * then no warning will be triggered on invalid or failed allocation
1672 : * requests.
1673 : *
1674 : * RETURNS:
1675 : * Percpu pointer to the allocated area on success, NULL on failure.
1676 : */
1677 2172 : static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1678 : gfp_t gfp)
1679 : {
1680 2172 : gfp_t pcpu_gfp;
1681 2172 : bool is_atomic;
1682 2172 : bool do_warn;
1683 2172 : enum pcpu_chunk_type type;
1684 2172 : struct list_head *pcpu_slot;
1685 2172 : struct obj_cgroup *objcg = NULL;
1686 2172 : static int warn_limit = 10;
1687 2172 : struct pcpu_chunk *chunk, *next;
1688 2172 : const char *err;
1689 2172 : int slot, off, cpu, ret;
1690 2172 : unsigned long flags;
1691 2172 : void __percpu *ptr;
1692 2172 : size_t bits, bit_align;
1693 :
1694 2172 : gfp = current_gfp_context(gfp);
1695 : /* whitelisted flags that can be passed to the backing allocators */
1696 2172 : pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1697 2172 : is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1698 2172 : do_warn = !(gfp & __GFP_NOWARN);
1699 :
1700 : /*
1701 : * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1702 : * therefore alignment must be a minimum of that many bytes.
1703 : * An allocation may have internal fragmentation from rounding up
1704 : * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1705 : */
1706 2172 : if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1707 1 : align = PCPU_MIN_ALLOC_SIZE;
1708 :
1709 2172 : size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1710 2172 : bits = size >> PCPU_MIN_ALLOC_SHIFT;
1711 2172 : bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1712 :
1713 4344 : if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1714 : !is_power_of_2(align))) {
1715 0 : WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1716 : size, align);
1717 0 : return NULL;
1718 : }
1719 :
1720 2172 : type = pcpu_memcg_pre_alloc_hook(size, gfp, &objcg);
1721 2172 : if (unlikely(type == PCPU_FAIL_ALLOC))
1722 : return NULL;
1723 2172 : pcpu_slot = pcpu_chunk_list(type);
1724 :
1725 2172 : if (!is_atomic) {
1726 : /*
1727 : * pcpu_balance_workfn() allocates memory under this mutex,
1728 : * and it may wait for memory reclaim. Allow current task
1729 : * to become OOM victim, in case of memory pressure.
1730 : */
1731 2172 : if (gfp & __GFP_NOFAIL) {
1732 0 : mutex_lock(&pcpu_alloc_mutex);
1733 2172 : } else if (mutex_lock_killable(&pcpu_alloc_mutex)) {
1734 2172 : pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1735 : return NULL;
1736 : }
1737 : }
1738 :
1739 2172 : spin_lock_irqsave(&pcpu_lock, flags);
1740 :
1741 : /* serve reserved allocations from the reserved chunk if available */
1742 2172 : if (reserved && pcpu_reserved_chunk) {
1743 0 : chunk = pcpu_reserved_chunk;
1744 :
1745 0 : off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1746 0 : if (off < 0) {
1747 0 : err = "alloc from reserved chunk failed";
1748 0 : goto fail_unlock;
1749 : }
1750 :
1751 0 : off = pcpu_alloc_area(chunk, bits, bit_align, off);
1752 0 : if (off >= 0)
1753 0 : goto area_found;
1754 :
1755 0 : err = "alloc from reserved chunk failed";
1756 0 : goto fail_unlock;
1757 : }
1758 :
1759 2172 : restart:
1760 : /* search through normal chunks */
1761 14801 : for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
1762 12630 : list_for_each_entry_safe(chunk, next, &pcpu_slot[slot], list) {
1763 2173 : off = pcpu_find_block_fit(chunk, bits, bit_align,
1764 : is_atomic);
1765 2173 : if (off < 0) {
1766 1 : if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1767 1 : pcpu_chunk_move(chunk, 0);
1768 1 : continue;
1769 : }
1770 :
1771 2172 : off = pcpu_alloc_area(chunk, bits, bit_align, off);
1772 2172 : if (off >= 0)
1773 2172 : goto area_found;
1774 :
1775 : }
1776 : }
1777 :
1778 0 : spin_unlock_irqrestore(&pcpu_lock, flags);
1779 :
1780 : /*
1781 : * No space left. Create a new chunk. We don't want multiple
1782 : * tasks to create chunks simultaneously. Serialize and create iff
1783 : * there's still no empty chunk after grabbing the mutex.
1784 : */
1785 0 : if (is_atomic) {
1786 0 : err = "atomic alloc failed, no space left";
1787 0 : goto fail;
1788 : }
1789 :
1790 0 : if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
1791 0 : chunk = pcpu_create_chunk(type, pcpu_gfp);
1792 0 : if (!chunk) {
1793 0 : err = "failed to allocate new chunk";
1794 0 : goto fail;
1795 : }
1796 :
1797 0 : spin_lock_irqsave(&pcpu_lock, flags);
1798 0 : pcpu_chunk_relocate(chunk, -1);
1799 : } else {
1800 0 : spin_lock_irqsave(&pcpu_lock, flags);
1801 : }
1802 :
1803 0 : goto restart;
1804 :
1805 2172 : area_found:
1806 2172 : pcpu_stats_area_alloc(chunk, size);
1807 2172 : spin_unlock_irqrestore(&pcpu_lock, flags);
1808 :
1809 : /* populate if not all pages are already there */
1810 2172 : if (!is_atomic) {
1811 2172 : unsigned int page_start, page_end, rs, re;
1812 :
1813 2172 : page_start = PFN_DOWN(off);
1814 2172 : page_end = PFN_UP(off + size);
1815 :
1816 2172 : bitmap_for_each_clear_region(chunk->populated, rs, re,
1817 : page_start, page_end) {
1818 0 : WARN_ON(chunk->immutable);
1819 :
1820 0 : ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1821 :
1822 0 : spin_lock_irqsave(&pcpu_lock, flags);
1823 0 : if (ret) {
1824 0 : pcpu_free_area(chunk, off);
1825 0 : err = "failed to populate";
1826 0 : goto fail_unlock;
1827 : }
1828 0 : pcpu_chunk_populated(chunk, rs, re);
1829 0 : spin_unlock_irqrestore(&pcpu_lock, flags);
1830 : }
1831 :
1832 2172 : mutex_unlock(&pcpu_alloc_mutex);
1833 : }
1834 :
1835 2172 : if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1836 4 : pcpu_schedule_balance_work();
1837 :
1838 : /* clear the areas and return address relative to base address */
1839 10860 : for_each_possible_cpu(cpu)
1840 8688 : memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1841 :
1842 2172 : ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1843 2172 : kmemleak_alloc_percpu(ptr, size, gfp);
1844 :
1845 2172 : trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
1846 : chunk->base_addr, off, ptr);
1847 :
1848 2172 : pcpu_memcg_post_alloc_hook(objcg, chunk, off, size);
1849 :
1850 2172 : return ptr;
1851 :
1852 0 : fail_unlock:
1853 0 : spin_unlock_irqrestore(&pcpu_lock, flags);
1854 0 : fail:
1855 0 : trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1856 :
1857 0 : if (!is_atomic && do_warn && warn_limit) {
1858 0 : pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1859 : size, align, is_atomic, err);
1860 0 : dump_stack();
1861 0 : if (!--warn_limit)
1862 0 : pr_info("limit reached, disable warning\n");
1863 : }
1864 0 : if (is_atomic) {
1865 : /* see the flag handling in pcpu_blance_workfn() */
1866 0 : pcpu_atomic_alloc_failed = true;
1867 0 : pcpu_schedule_balance_work();
1868 : } else {
1869 0 : mutex_unlock(&pcpu_alloc_mutex);
1870 : }
1871 :
1872 2172 : pcpu_memcg_post_alloc_hook(objcg, NULL, 0, size);
1873 :
1874 : return NULL;
1875 : }
1876 :
1877 : /**
1878 : * __alloc_percpu_gfp - allocate dynamic percpu area
1879 : * @size: size of area to allocate in bytes
1880 : * @align: alignment of area (max PAGE_SIZE)
1881 : * @gfp: allocation flags
1882 : *
1883 : * Allocate zero-filled percpu area of @size bytes aligned at @align. If
1884 : * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1885 : * be called from any context but is a lot more likely to fail. If @gfp
1886 : * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1887 : * allocation requests.
1888 : *
1889 : * RETURNS:
1890 : * Percpu pointer to the allocated area on success, NULL on failure.
1891 : */
1892 323 : void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1893 : {
1894 323 : return pcpu_alloc(size, align, false, gfp);
1895 : }
1896 : EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1897 :
1898 : /**
1899 : * __alloc_percpu - allocate dynamic percpu area
1900 : * @size: size of area to allocate in bytes
1901 : * @align: alignment of area (max PAGE_SIZE)
1902 : *
1903 : * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1904 : */
1905 1849 : void __percpu *__alloc_percpu(size_t size, size_t align)
1906 : {
1907 1849 : return pcpu_alloc(size, align, false, GFP_KERNEL);
1908 : }
1909 : EXPORT_SYMBOL_GPL(__alloc_percpu);
1910 :
1911 : /**
1912 : * __alloc_reserved_percpu - allocate reserved percpu area
1913 : * @size: size of area to allocate in bytes
1914 : * @align: alignment of area (max PAGE_SIZE)
1915 : *
1916 : * Allocate zero-filled percpu area of @size bytes aligned at @align
1917 : * from reserved percpu area if arch has set it up; otherwise,
1918 : * allocation is served from the same dynamic area. Might sleep.
1919 : * Might trigger writeouts.
1920 : *
1921 : * CONTEXT:
1922 : * Does GFP_KERNEL allocation.
1923 : *
1924 : * RETURNS:
1925 : * Percpu pointer to the allocated area on success, NULL on failure.
1926 : */
1927 0 : void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1928 : {
1929 0 : return pcpu_alloc(size, align, true, GFP_KERNEL);
1930 : }
1931 :
1932 : /**
1933 : * __pcpu_balance_workfn - manage the amount of free chunks and populated pages
1934 : * @type: chunk type
1935 : *
1936 : * Reclaim all fully free chunks except for the first one. This is also
1937 : * responsible for maintaining the pool of empty populated pages. However,
1938 : * it is possible that this is called when physical memory is scarce causing
1939 : * OOM killer to be triggered. We should avoid doing so until an actual
1940 : * allocation causes the failure as it is possible that requests can be
1941 : * serviced from already backed regions.
1942 : */
1943 1 : static void __pcpu_balance_workfn(enum pcpu_chunk_type type)
1944 : {
1945 : /* gfp flags passed to underlying allocators */
1946 1 : const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
1947 1 : LIST_HEAD(to_free);
1948 1 : struct list_head *pcpu_slot = pcpu_chunk_list(type);
1949 1 : struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
1950 1 : struct pcpu_chunk *chunk, *next;
1951 1 : int slot, nr_to_pop, ret;
1952 :
1953 : /*
1954 : * There's no reason to keep around multiple unused chunks and VM
1955 : * areas can be scarce. Destroy all free chunks except for one.
1956 : */
1957 1 : mutex_lock(&pcpu_alloc_mutex);
1958 1 : spin_lock_irq(&pcpu_lock);
1959 :
1960 1 : list_for_each_entry_safe(chunk, next, free_head, list) {
1961 0 : WARN_ON(chunk->immutable);
1962 :
1963 : /* spare the first one */
1964 0 : if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1965 0 : continue;
1966 :
1967 0 : list_move(&chunk->list, &to_free);
1968 : }
1969 :
1970 1 : spin_unlock_irq(&pcpu_lock);
1971 :
1972 1 : list_for_each_entry_safe(chunk, next, &to_free, list) {
1973 0 : unsigned int rs, re;
1974 :
1975 0 : bitmap_for_each_set_region(chunk->populated, rs, re, 0,
1976 : chunk->nr_pages) {
1977 0 : pcpu_depopulate_chunk(chunk, rs, re);
1978 0 : spin_lock_irq(&pcpu_lock);
1979 0 : pcpu_chunk_depopulated(chunk, rs, re);
1980 0 : spin_unlock_irq(&pcpu_lock);
1981 : }
1982 0 : pcpu_destroy_chunk(chunk);
1983 0 : cond_resched();
1984 : }
1985 :
1986 : /*
1987 : * Ensure there are certain number of free populated pages for
1988 : * atomic allocs. Fill up from the most packed so that atomic
1989 : * allocs don't increase fragmentation. If atomic allocation
1990 : * failed previously, always populate the maximum amount. This
1991 : * should prevent atomic allocs larger than PAGE_SIZE from keeping
1992 : * failing indefinitely; however, large atomic allocs are not
1993 : * something we support properly and can be highly unreliable and
1994 : * inefficient.
1995 : */
1996 1 : retry_pop:
1997 2 : if (pcpu_atomic_alloc_failed) {
1998 0 : nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
1999 : /* best effort anyway, don't worry about synchronization */
2000 0 : pcpu_atomic_alloc_failed = false;
2001 : } else {
2002 2 : nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
2003 : pcpu_nr_empty_pop_pages,
2004 : 0, PCPU_EMPTY_POP_PAGES_HIGH);
2005 : }
2006 :
2007 22 : for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
2008 18 : unsigned int nr_unpop = 0, rs, re;
2009 :
2010 18 : if (!nr_to_pop)
2011 : break;
2012 :
2013 18 : spin_lock_irq(&pcpu_lock);
2014 20 : list_for_each_entry(chunk, &pcpu_slot[slot], list) {
2015 3 : nr_unpop = chunk->nr_pages - chunk->nr_populated;
2016 3 : if (nr_unpop)
2017 : break;
2018 : }
2019 18 : spin_unlock_irq(&pcpu_lock);
2020 :
2021 18 : if (!nr_unpop)
2022 17 : continue;
2023 :
2024 : /* @chunk can't go away while pcpu_alloc_mutex is held */
2025 1 : bitmap_for_each_clear_region(chunk->populated, rs, re, 0,
2026 : chunk->nr_pages) {
2027 1 : int nr = min_t(int, re - rs, nr_to_pop);
2028 :
2029 1 : ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
2030 1 : if (!ret) {
2031 1 : nr_to_pop -= nr;
2032 1 : spin_lock_irq(&pcpu_lock);
2033 1 : pcpu_chunk_populated(chunk, rs, rs + nr);
2034 2 : spin_unlock_irq(&pcpu_lock);
2035 : } else {
2036 : nr_to_pop = 0;
2037 : }
2038 :
2039 1 : if (!nr_to_pop)
2040 : break;
2041 : }
2042 : }
2043 :
2044 2 : if (nr_to_pop) {
2045 : /* ran out of chunks to populate, create a new one and retry */
2046 1 : chunk = pcpu_create_chunk(type, gfp);
2047 1 : if (chunk) {
2048 1 : spin_lock_irq(&pcpu_lock);
2049 1 : pcpu_chunk_relocate(chunk, -1);
2050 1 : spin_unlock_irq(&pcpu_lock);
2051 1 : goto retry_pop;
2052 : }
2053 : }
2054 :
2055 1 : mutex_unlock(&pcpu_alloc_mutex);
2056 1 : }
2057 :
2058 : /**
2059 : * pcpu_balance_workfn - manage the amount of free chunks and populated pages
2060 : * @work: unused
2061 : *
2062 : * Call __pcpu_balance_workfn() for each chunk type.
2063 : */
2064 1 : static void pcpu_balance_workfn(struct work_struct *work)
2065 : {
2066 1 : enum pcpu_chunk_type type;
2067 :
2068 2 : for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
2069 1 : __pcpu_balance_workfn(type);
2070 1 : }
2071 :
2072 : /**
2073 : * free_percpu - free percpu area
2074 : * @ptr: pointer to area to free
2075 : *
2076 : * Free percpu area @ptr.
2077 : *
2078 : * CONTEXT:
2079 : * Can be called from atomic context.
2080 : */
2081 1653 : void free_percpu(void __percpu *ptr)
2082 : {
2083 1653 : void *addr;
2084 1653 : struct pcpu_chunk *chunk;
2085 1653 : unsigned long flags;
2086 1653 : int size, off;
2087 1653 : bool need_balance = false;
2088 1653 : struct list_head *pcpu_slot;
2089 :
2090 1653 : if (!ptr)
2091 : return;
2092 :
2093 1558 : kmemleak_free_percpu(ptr);
2094 :
2095 1558 : addr = __pcpu_ptr_to_addr(ptr);
2096 :
2097 1558 : spin_lock_irqsave(&pcpu_lock, flags);
2098 :
2099 1558 : chunk = pcpu_chunk_addr_search(addr);
2100 1558 : off = addr - chunk->base_addr;
2101 :
2102 1558 : size = pcpu_free_area(chunk, off);
2103 :
2104 1558 : pcpu_slot = pcpu_chunk_list(pcpu_chunk_type(chunk));
2105 :
2106 1558 : pcpu_memcg_free_hook(chunk, off, size);
2107 :
2108 : /* if there are more than one fully free chunks, wake up grim reaper */
2109 1558 : if (chunk->free_bytes == pcpu_unit_size) {
2110 0 : struct pcpu_chunk *pos;
2111 :
2112 0 : list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
2113 0 : if (pos != chunk) {
2114 : need_balance = true;
2115 : break;
2116 : }
2117 : }
2118 :
2119 1558 : trace_percpu_free_percpu(chunk->base_addr, off, ptr);
2120 :
2121 1558 : spin_unlock_irqrestore(&pcpu_lock, flags);
2122 :
2123 1558 : if (need_balance)
2124 0 : pcpu_schedule_balance_work();
2125 : }
2126 : EXPORT_SYMBOL_GPL(free_percpu);
2127 :
2128 333 : bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
2129 : {
2130 : #ifdef CONFIG_SMP
2131 333 : const size_t static_size = __per_cpu_end - __per_cpu_start;
2132 333 : void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2133 333 : unsigned int cpu;
2134 :
2135 1553 : for_each_possible_cpu(cpu) {
2136 1244 : void *start = per_cpu_ptr(base, cpu);
2137 1244 : void *va = (void *)addr;
2138 :
2139 1244 : if (va >= start && va < start + static_size) {
2140 24 : if (can_addr) {
2141 24 : *can_addr = (unsigned long) (va - start);
2142 24 : *can_addr += (unsigned long)
2143 24 : per_cpu_ptr(base, get_boot_cpu_id());
2144 : }
2145 24 : return true;
2146 : }
2147 : }
2148 : #endif
2149 : /* on UP, can't distinguish from other static vars, always false */
2150 : return false;
2151 : }
2152 :
2153 : /**
2154 : * is_kernel_percpu_address - test whether address is from static percpu area
2155 : * @addr: address to test
2156 : *
2157 : * Test whether @addr belongs to in-kernel static percpu area. Module
2158 : * static percpu areas are not considered. For those, use
2159 : * is_module_percpu_address().
2160 : *
2161 : * RETURNS:
2162 : * %true if @addr is from in-kernel static percpu area, %false otherwise.
2163 : */
2164 85 : bool is_kernel_percpu_address(unsigned long addr)
2165 : {
2166 85 : return __is_kernel_percpu_address(addr, NULL);
2167 : }
2168 :
2169 : /**
2170 : * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2171 : * @addr: the address to be converted to physical address
2172 : *
2173 : * Given @addr which is dereferenceable address obtained via one of
2174 : * percpu access macros, this function translates it into its physical
2175 : * address. The caller is responsible for ensuring @addr stays valid
2176 : * until this function finishes.
2177 : *
2178 : * percpu allocator has special setup for the first chunk, which currently
2179 : * supports either embedding in linear address space or vmalloc mapping,
2180 : * and, from the second one, the backing allocator (currently either vm or
2181 : * km) provides translation.
2182 : *
2183 : * The addr can be translated simply without checking if it falls into the
2184 : * first chunk. But the current code reflects better how percpu allocator
2185 : * actually works, and the verification can discover both bugs in percpu
2186 : * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2187 : * code.
2188 : *
2189 : * RETURNS:
2190 : * The physical address for @addr.
2191 : */
2192 64 : phys_addr_t per_cpu_ptr_to_phys(void *addr)
2193 : {
2194 64 : void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2195 64 : bool in_first_chunk = false;
2196 64 : unsigned long first_low, first_high;
2197 64 : unsigned int cpu;
2198 :
2199 : /*
2200 : * The following test on unit_low/high isn't strictly
2201 : * necessary but will speed up lookups of addresses which
2202 : * aren't in the first chunk.
2203 : *
2204 : * The address check is against full chunk sizes. pcpu_base_addr
2205 : * points to the beginning of the first chunk including the
2206 : * static region. Assumes good intent as the first chunk may
2207 : * not be full (ie. < pcpu_unit_pages in size).
2208 : */
2209 64 : first_low = (unsigned long)pcpu_base_addr +
2210 64 : pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2211 64 : first_high = (unsigned long)pcpu_base_addr +
2212 64 : pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2213 64 : if ((unsigned long)addr >= first_low &&
2214 64 : (unsigned long)addr < first_high) {
2215 160 : for_each_possible_cpu(cpu) {
2216 160 : void *start = per_cpu_ptr(base, cpu);
2217 :
2218 160 : if (addr >= start && addr < start + pcpu_unit_size) {
2219 : in_first_chunk = true;
2220 : break;
2221 : }
2222 : }
2223 : }
2224 :
2225 64 : if (in_first_chunk) {
2226 64 : if (!is_vmalloc_addr(addr))
2227 64 : return __pa(addr);
2228 : else
2229 0 : return page_to_phys(vmalloc_to_page(addr)) +
2230 0 : offset_in_page(addr);
2231 : } else
2232 0 : return page_to_phys(pcpu_addr_to_page(addr)) +
2233 0 : offset_in_page(addr);
2234 : }
2235 :
2236 : /**
2237 : * pcpu_alloc_alloc_info - allocate percpu allocation info
2238 : * @nr_groups: the number of groups
2239 : * @nr_units: the number of units
2240 : *
2241 : * Allocate ai which is large enough for @nr_groups groups containing
2242 : * @nr_units units. The returned ai's groups[0].cpu_map points to the
2243 : * cpu_map array which is long enough for @nr_units and filled with
2244 : * NR_CPUS. It's the caller's responsibility to initialize cpu_map
2245 : * pointer of other groups.
2246 : *
2247 : * RETURNS:
2248 : * Pointer to the allocated pcpu_alloc_info on success, NULL on
2249 : * failure.
2250 : */
2251 1 : struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2252 : int nr_units)
2253 : {
2254 1 : struct pcpu_alloc_info *ai;
2255 1 : size_t base_size, ai_size;
2256 1 : void *ptr;
2257 1 : int unit;
2258 :
2259 0 : base_size = ALIGN(struct_size(ai, groups, nr_groups),
2260 : __alignof__(ai->groups[0].cpu_map[0]));
2261 1 : ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2262 :
2263 1 : ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2264 1 : if (!ptr)
2265 : return NULL;
2266 1 : ai = ptr;
2267 1 : ptr += base_size;
2268 :
2269 1 : ai->groups[0].cpu_map = ptr;
2270 :
2271 5 : for (unit = 0; unit < nr_units; unit++)
2272 4 : ai->groups[0].cpu_map[unit] = NR_CPUS;
2273 :
2274 1 : ai->nr_groups = nr_groups;
2275 1 : ai->__ai_size = PFN_ALIGN(ai_size);
2276 :
2277 0 : return ai;
2278 : }
2279 :
2280 : /**
2281 : * pcpu_free_alloc_info - free percpu allocation info
2282 : * @ai: pcpu_alloc_info to free
2283 : *
2284 : * Free @ai which was allocated by pcpu_alloc_alloc_info().
2285 : */
2286 1 : void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2287 : {
2288 1 : memblock_free_early(__pa(ai), ai->__ai_size);
2289 1 : }
2290 :
2291 : /**
2292 : * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2293 : * @lvl: loglevel
2294 : * @ai: allocation info to dump
2295 : *
2296 : * Print out information about @ai using loglevel @lvl.
2297 : */
2298 1 : static void pcpu_dump_alloc_info(const char *lvl,
2299 : const struct pcpu_alloc_info *ai)
2300 : {
2301 1 : int group_width = 1, cpu_width = 1, width;
2302 1 : char empty_str[] = "--------";
2303 1 : int alloc = 0, alloc_end = 0;
2304 1 : int group, v;
2305 1 : int upa, apl; /* units per alloc, allocs per line */
2306 :
2307 1 : v = ai->nr_groups;
2308 1 : while (v /= 10)
2309 0 : group_width++;
2310 :
2311 1 : v = num_possible_cpus();
2312 1 : while (v /= 10)
2313 0 : cpu_width++;
2314 1 : empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2315 :
2316 1 : upa = ai->alloc_size / ai->unit_size;
2317 1 : width = upa * (cpu_width + 1) + group_width + 3;
2318 1 : apl = rounddown_pow_of_two(max(60 / width, 1));
2319 :
2320 1 : printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2321 : lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2322 : ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2323 :
2324 3 : for (group = 0; group < ai->nr_groups; group++) {
2325 1 : const struct pcpu_group_info *gi = &ai->groups[group];
2326 1 : int unit = 0, unit_end = 0;
2327 :
2328 1 : BUG_ON(gi->nr_units % upa);
2329 1 : for (alloc_end += gi->nr_units / upa;
2330 2 : alloc < alloc_end; alloc++) {
2331 1 : if (!(alloc % apl)) {
2332 1 : pr_cont("\n");
2333 1 : printk("%spcpu-alloc: ", lvl);
2334 : }
2335 1 : pr_cont("[%0*d] ", group_width, group);
2336 :
2337 5 : for (unit_end += upa; unit < unit_end; unit++)
2338 4 : if (gi->cpu_map[unit] != NR_CPUS)
2339 4 : pr_cont("%0*d ",
2340 : cpu_width, gi->cpu_map[unit]);
2341 : else
2342 0 : pr_cont("%s ", empty_str);
2343 : }
2344 : }
2345 1 : pr_cont("\n");
2346 1 : }
2347 :
2348 : /**
2349 : * pcpu_setup_first_chunk - initialize the first percpu chunk
2350 : * @ai: pcpu_alloc_info describing how to percpu area is shaped
2351 : * @base_addr: mapped address
2352 : *
2353 : * Initialize the first percpu chunk which contains the kernel static
2354 : * percpu area. This function is to be called from arch percpu area
2355 : * setup path.
2356 : *
2357 : * @ai contains all information necessary to initialize the first
2358 : * chunk and prime the dynamic percpu allocator.
2359 : *
2360 : * @ai->static_size is the size of static percpu area.
2361 : *
2362 : * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2363 : * reserve after the static area in the first chunk. This reserves
2364 : * the first chunk such that it's available only through reserved
2365 : * percpu allocation. This is primarily used to serve module percpu
2366 : * static areas on architectures where the addressing model has
2367 : * limited offset range for symbol relocations to guarantee module
2368 : * percpu symbols fall inside the relocatable range.
2369 : *
2370 : * @ai->dyn_size determines the number of bytes available for dynamic
2371 : * allocation in the first chunk. The area between @ai->static_size +
2372 : * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2373 : *
2374 : * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2375 : * and equal to or larger than @ai->static_size + @ai->reserved_size +
2376 : * @ai->dyn_size.
2377 : *
2378 : * @ai->atom_size is the allocation atom size and used as alignment
2379 : * for vm areas.
2380 : *
2381 : * @ai->alloc_size is the allocation size and always multiple of
2382 : * @ai->atom_size. This is larger than @ai->atom_size if
2383 : * @ai->unit_size is larger than @ai->atom_size.
2384 : *
2385 : * @ai->nr_groups and @ai->groups describe virtual memory layout of
2386 : * percpu areas. Units which should be colocated are put into the
2387 : * same group. Dynamic VM areas will be allocated according to these
2388 : * groupings. If @ai->nr_groups is zero, a single group containing
2389 : * all units is assumed.
2390 : *
2391 : * The caller should have mapped the first chunk at @base_addr and
2392 : * copied static data to each unit.
2393 : *
2394 : * The first chunk will always contain a static and a dynamic region.
2395 : * However, the static region is not managed by any chunk. If the first
2396 : * chunk also contains a reserved region, it is served by two chunks -
2397 : * one for the reserved region and one for the dynamic region. They
2398 : * share the same vm, but use offset regions in the area allocation map.
2399 : * The chunk serving the dynamic region is circulated in the chunk slots
2400 : * and available for dynamic allocation like any other chunk.
2401 : */
2402 1 : void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2403 : void *base_addr)
2404 : {
2405 1 : size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2406 1 : size_t static_size, dyn_size;
2407 1 : struct pcpu_chunk *chunk;
2408 1 : unsigned long *group_offsets;
2409 1 : size_t *group_sizes;
2410 1 : unsigned long *unit_off;
2411 1 : unsigned int cpu;
2412 1 : int *unit_map;
2413 1 : int group, unit, i;
2414 1 : int map_size;
2415 1 : unsigned long tmp_addr;
2416 1 : size_t alloc_size;
2417 1 : enum pcpu_chunk_type type;
2418 :
2419 : #define PCPU_SETUP_BUG_ON(cond) do { \
2420 : if (unlikely(cond)) { \
2421 : pr_emerg("failed to initialize, %s\n", #cond); \
2422 : pr_emerg("cpu_possible_mask=%*pb\n", \
2423 : cpumask_pr_args(cpu_possible_mask)); \
2424 : pcpu_dump_alloc_info(KERN_EMERG, ai); \
2425 : BUG(); \
2426 : } \
2427 : } while (0)
2428 :
2429 : /* sanity checks */
2430 1 : PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2431 : #ifdef CONFIG_SMP
2432 1 : PCPU_SETUP_BUG_ON(!ai->static_size);
2433 1 : PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2434 : #endif
2435 1 : PCPU_SETUP_BUG_ON(!base_addr);
2436 1 : PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2437 1 : PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2438 1 : PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2439 1 : PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2440 1 : PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2441 1 : PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2442 1 : PCPU_SETUP_BUG_ON(!ai->dyn_size);
2443 1 : PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2444 1 : PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2445 : IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2446 1 : PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2447 :
2448 : /* process group information and build config tables accordingly */
2449 1 : alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2450 1 : group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2451 1 : if (!group_offsets)
2452 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
2453 : alloc_size);
2454 :
2455 1 : alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2456 1 : group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2457 1 : if (!group_sizes)
2458 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
2459 : alloc_size);
2460 :
2461 1 : alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2462 1 : unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2463 1 : if (!unit_map)
2464 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
2465 : alloc_size);
2466 :
2467 1 : alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2468 1 : unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2469 1 : if (!unit_off)
2470 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
2471 : alloc_size);
2472 :
2473 5 : for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2474 4 : unit_map[cpu] = UINT_MAX;
2475 :
2476 1 : pcpu_low_unit_cpu = NR_CPUS;
2477 1 : pcpu_high_unit_cpu = NR_CPUS;
2478 :
2479 2 : for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2480 1 : const struct pcpu_group_info *gi = &ai->groups[group];
2481 :
2482 1 : group_offsets[group] = gi->base_offset;
2483 1 : group_sizes[group] = gi->nr_units * ai->unit_size;
2484 :
2485 5 : for (i = 0; i < gi->nr_units; i++) {
2486 4 : cpu = gi->cpu_map[i];
2487 4 : if (cpu == NR_CPUS)
2488 0 : continue;
2489 :
2490 4 : PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2491 4 : PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2492 4 : PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2493 :
2494 4 : unit_map[cpu] = unit + i;
2495 4 : unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2496 :
2497 : /* determine low/high unit_cpu */
2498 4 : if (pcpu_low_unit_cpu == NR_CPUS ||
2499 3 : unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2500 1 : pcpu_low_unit_cpu = cpu;
2501 4 : if (pcpu_high_unit_cpu == NR_CPUS ||
2502 3 : unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2503 4 : pcpu_high_unit_cpu = cpu;
2504 : }
2505 : }
2506 1 : pcpu_nr_units = unit;
2507 :
2508 6 : for_each_possible_cpu(cpu)
2509 5 : PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2510 :
2511 : /* we're done parsing the input, undefine BUG macro and dump config */
2512 : #undef PCPU_SETUP_BUG_ON
2513 1 : pcpu_dump_alloc_info(KERN_DEBUG, ai);
2514 :
2515 1 : pcpu_nr_groups = ai->nr_groups;
2516 1 : pcpu_group_offsets = group_offsets;
2517 1 : pcpu_group_sizes = group_sizes;
2518 1 : pcpu_unit_map = unit_map;
2519 1 : pcpu_unit_offsets = unit_off;
2520 :
2521 : /* determine basic parameters */
2522 1 : pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2523 1 : pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2524 1 : pcpu_atom_size = ai->atom_size;
2525 1 : pcpu_chunk_struct_size = struct_size(chunk, populated,
2526 : BITS_TO_LONGS(pcpu_unit_pages));
2527 :
2528 1 : pcpu_stats_save_ai(ai);
2529 :
2530 : /*
2531 : * Allocate chunk slots. The additional last slot is for
2532 : * empty chunks.
2533 : */
2534 1 : pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
2535 2 : pcpu_chunk_lists = memblock_alloc(pcpu_nr_slots *
2536 1 : sizeof(pcpu_chunk_lists[0]) *
2537 : PCPU_NR_CHUNK_TYPES,
2538 : SMP_CACHE_BYTES);
2539 1 : if (!pcpu_chunk_lists)
2540 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
2541 : pcpu_nr_slots * sizeof(pcpu_chunk_lists[0]) *
2542 : PCPU_NR_CHUNK_TYPES);
2543 :
2544 2 : for (type = 0; type < PCPU_NR_CHUNK_TYPES; type++)
2545 20 : for (i = 0; i < pcpu_nr_slots; i++)
2546 19 : INIT_LIST_HEAD(&pcpu_chunk_list(type)[i]);
2547 :
2548 : /*
2549 : * The end of the static region needs to be aligned with the
2550 : * minimum allocation size as this offsets the reserved and
2551 : * dynamic region. The first chunk ends page aligned by
2552 : * expanding the dynamic region, therefore the dynamic region
2553 : * can be shrunk to compensate while still staying above the
2554 : * configured sizes.
2555 : */
2556 1 : static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2557 1 : dyn_size = ai->dyn_size - (static_size - ai->static_size);
2558 :
2559 : /*
2560 : * Initialize first chunk.
2561 : * If the reserved_size is non-zero, this initializes the reserved
2562 : * chunk. If the reserved_size is zero, the reserved chunk is NULL
2563 : * and the dynamic region is initialized here. The first chunk,
2564 : * pcpu_first_chunk, will always point to the chunk that serves
2565 : * the dynamic region.
2566 : */
2567 1 : tmp_addr = (unsigned long)base_addr + static_size;
2568 1 : map_size = ai->reserved_size ?: dyn_size;
2569 1 : chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2570 :
2571 : /* init dynamic chunk if necessary */
2572 1 : if (ai->reserved_size) {
2573 0 : pcpu_reserved_chunk = chunk;
2574 :
2575 0 : tmp_addr = (unsigned long)base_addr + static_size +
2576 : ai->reserved_size;
2577 0 : map_size = dyn_size;
2578 0 : chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2579 : }
2580 :
2581 : /* link the first chunk in */
2582 1 : pcpu_first_chunk = chunk;
2583 1 : pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2584 1 : pcpu_chunk_relocate(pcpu_first_chunk, -1);
2585 :
2586 : /* include all regions of the first chunk */
2587 1 : pcpu_nr_populated += PFN_DOWN(size_sum);
2588 :
2589 1 : pcpu_stats_chunk_alloc();
2590 1 : trace_percpu_create_chunk(base_addr);
2591 :
2592 : /* we're done */
2593 1 : pcpu_base_addr = base_addr;
2594 1 : }
2595 :
2596 : #ifdef CONFIG_SMP
2597 :
2598 : const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2599 : [PCPU_FC_AUTO] = "auto",
2600 : [PCPU_FC_EMBED] = "embed",
2601 : [PCPU_FC_PAGE] = "page",
2602 : };
2603 :
2604 : enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2605 :
2606 0 : static int __init percpu_alloc_setup(char *str)
2607 : {
2608 0 : if (!str)
2609 : return -EINVAL;
2610 :
2611 0 : if (0)
2612 : /* nada */;
2613 : #ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2614 0 : else if (!strcmp(str, "embed"))
2615 0 : pcpu_chosen_fc = PCPU_FC_EMBED;
2616 : #endif
2617 : #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2618 0 : else if (!strcmp(str, "page"))
2619 0 : pcpu_chosen_fc = PCPU_FC_PAGE;
2620 : #endif
2621 : else
2622 0 : pr_warn("unknown allocator %s specified\n", str);
2623 :
2624 : return 0;
2625 : }
2626 : early_param("percpu_alloc", percpu_alloc_setup);
2627 :
2628 : /*
2629 : * pcpu_embed_first_chunk() is used by the generic percpu setup.
2630 : * Build it if needed by the arch config or the generic setup is going
2631 : * to be used.
2632 : */
2633 : #if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2634 : !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2635 : #define BUILD_EMBED_FIRST_CHUNK
2636 : #endif
2637 :
2638 : /* build pcpu_page_first_chunk() iff needed by the arch config */
2639 : #if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2640 : #define BUILD_PAGE_FIRST_CHUNK
2641 : #endif
2642 :
2643 : /* pcpu_build_alloc_info() is used by both embed and page first chunk */
2644 : #if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2645 : /**
2646 : * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2647 : * @reserved_size: the size of reserved percpu area in bytes
2648 : * @dyn_size: minimum free size for dynamic allocation in bytes
2649 : * @atom_size: allocation atom size
2650 : * @cpu_distance_fn: callback to determine distance between cpus, optional
2651 : *
2652 : * This function determines grouping of units, their mappings to cpus
2653 : * and other parameters considering needed percpu size, allocation
2654 : * atom size and distances between CPUs.
2655 : *
2656 : * Groups are always multiples of atom size and CPUs which are of
2657 : * LOCAL_DISTANCE both ways are grouped together and share space for
2658 : * units in the same group. The returned configuration is guaranteed
2659 : * to have CPUs on different nodes on different groups and >=75% usage
2660 : * of allocated virtual address space.
2661 : *
2662 : * RETURNS:
2663 : * On success, pointer to the new allocation_info is returned. On
2664 : * failure, ERR_PTR value is returned.
2665 : */
2666 1 : static struct pcpu_alloc_info * __init __flatten pcpu_build_alloc_info(
2667 : size_t reserved_size, size_t dyn_size,
2668 : size_t atom_size,
2669 : pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2670 : {
2671 1 : static int group_map[NR_CPUS] __initdata;
2672 1 : static int group_cnt[NR_CPUS] __initdata;
2673 1 : static struct cpumask mask __initdata;
2674 1 : const size_t static_size = __per_cpu_end - __per_cpu_start;
2675 1 : int nr_groups = 1, nr_units = 0;
2676 1 : size_t size_sum, min_unit_size, alloc_size;
2677 1 : int upa, max_upa, best_upa; /* units_per_alloc */
2678 1 : int last_allocs, group, unit;
2679 1 : unsigned int cpu, tcpu;
2680 1 : struct pcpu_alloc_info *ai;
2681 1 : unsigned int *cpu_map;
2682 :
2683 : /* this function may be called multiple times */
2684 1 : memset(group_map, 0, sizeof(group_map));
2685 1 : memset(group_cnt, 0, sizeof(group_cnt));
2686 1 : cpumask_clear(&mask);
2687 :
2688 : /* calculate size_sum and ensure dyn_size is enough for early alloc */
2689 1 : size_sum = PFN_ALIGN(static_size + reserved_size +
2690 : max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2691 1 : dyn_size = size_sum - static_size - reserved_size;
2692 :
2693 : /*
2694 : * Determine min_unit_size, alloc_size and max_upa such that
2695 : * alloc_size is multiple of atom_size and is the smallest
2696 : * which can accommodate 4k aligned segments which are equal to
2697 : * or larger than min_unit_size.
2698 : */
2699 1 : min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2700 :
2701 : /* determine the maximum # of units that can fit in an allocation */
2702 1 : alloc_size = roundup(min_unit_size, atom_size);
2703 1 : upa = alloc_size / min_unit_size;
2704 3 : while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2705 2 : upa--;
2706 1 : max_upa = upa;
2707 :
2708 1 : cpumask_copy(&mask, cpu_possible_mask);
2709 :
2710 : /* group cpus according to their proximity */
2711 2 : for (group = 0; !cpumask_empty(&mask); group++) {
2712 : /* pop the group's first cpu */
2713 1 : cpu = cpumask_first(&mask);
2714 1 : group_map[cpu] = group;
2715 1 : group_cnt[group]++;
2716 1 : cpumask_clear_cpu(cpu, &mask);
2717 :
2718 4 : for_each_cpu(tcpu, &mask) {
2719 6 : if (!cpu_distance_fn ||
2720 6 : (cpu_distance_fn(cpu, tcpu) == LOCAL_DISTANCE &&
2721 3 : cpu_distance_fn(tcpu, cpu) == LOCAL_DISTANCE)) {
2722 3 : group_map[tcpu] = group;
2723 3 : group_cnt[group]++;
2724 7 : cpumask_clear_cpu(tcpu, &mask);
2725 : }
2726 : }
2727 : }
2728 3 : nr_groups = group;
2729 :
2730 : /*
2731 : * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2732 : * Expand the unit_size until we use >= 75% of the units allocated.
2733 : * Related to atom_size, which could be much larger than the unit_size.
2734 : */
2735 : last_allocs = INT_MAX;
2736 3 : for (upa = max_upa; upa; upa--) {
2737 3 : int allocs = 0, wasted = 0;
2738 :
2739 3 : if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2740 1 : continue;
2741 :
2742 4 : for (group = 0; group < nr_groups; group++) {
2743 2 : int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2744 2 : allocs += this_allocs;
2745 2 : wasted += this_allocs * upa - group_cnt[group];
2746 : }
2747 :
2748 : /*
2749 : * Don't accept if wastage is over 1/3. The
2750 : * greater-than comparison ensures upa==1 always
2751 : * passes the following check.
2752 : */
2753 4 : if (wasted > num_possible_cpus() / 3)
2754 0 : continue;
2755 :
2756 : /* and then don't consume more memory */
2757 2 : if (allocs > last_allocs)
2758 : break;
2759 : last_allocs = allocs;
2760 : best_upa = upa;
2761 : }
2762 1 : upa = best_upa;
2763 :
2764 : /* allocate and fill alloc_info */
2765 2 : for (group = 0; group < nr_groups; group++)
2766 1 : nr_units += roundup(group_cnt[group], upa);
2767 :
2768 1 : ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2769 1 : if (!ai)
2770 1 : return ERR_PTR(-ENOMEM);
2771 1 : cpu_map = ai->groups[0].cpu_map;
2772 :
2773 2 : for (group = 0; group < nr_groups; group++) {
2774 1 : ai->groups[group].cpu_map = cpu_map;
2775 1 : cpu_map += roundup(group_cnt[group], upa);
2776 : }
2777 :
2778 1 : ai->static_size = static_size;
2779 1 : ai->reserved_size = reserved_size;
2780 1 : ai->dyn_size = dyn_size;
2781 1 : ai->unit_size = alloc_size / upa;
2782 1 : ai->atom_size = atom_size;
2783 1 : ai->alloc_size = alloc_size;
2784 :
2785 2 : for (group = 0, unit = 0; group < nr_groups; group++) {
2786 1 : struct pcpu_group_info *gi = &ai->groups[group];
2787 :
2788 : /*
2789 : * Initialize base_offset as if all groups are located
2790 : * back-to-back. The caller should update this to
2791 : * reflect actual allocation.
2792 : */
2793 1 : gi->base_offset = unit * ai->unit_size;
2794 :
2795 5 : for_each_possible_cpu(cpu)
2796 4 : if (group_map[cpu] == group)
2797 4 : gi->cpu_map[gi->nr_units++] = cpu;
2798 1 : gi->nr_units = roundup(gi->nr_units, upa);
2799 1 : unit += gi->nr_units;
2800 : }
2801 1 : BUG_ON(unit != nr_units);
2802 :
2803 : return ai;
2804 : }
2805 : #endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
2806 :
2807 : #if defined(BUILD_EMBED_FIRST_CHUNK)
2808 : /**
2809 : * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
2810 : * @reserved_size: the size of reserved percpu area in bytes
2811 : * @dyn_size: minimum free size for dynamic allocation in bytes
2812 : * @atom_size: allocation atom size
2813 : * @cpu_distance_fn: callback to determine distance between cpus, optional
2814 : * @alloc_fn: function to allocate percpu page
2815 : * @free_fn: function to free percpu page
2816 : *
2817 : * This is a helper to ease setting up embedded first percpu chunk and
2818 : * can be called where pcpu_setup_first_chunk() is expected.
2819 : *
2820 : * If this function is used to setup the first chunk, it is allocated
2821 : * by calling @alloc_fn and used as-is without being mapped into
2822 : * vmalloc area. Allocations are always whole multiples of @atom_size
2823 : * aligned to @atom_size.
2824 : *
2825 : * This enables the first chunk to piggy back on the linear physical
2826 : * mapping which often uses larger page size. Please note that this
2827 : * can result in very sparse cpu->unit mapping on NUMA machines thus
2828 : * requiring large vmalloc address space. Don't use this allocator if
2829 : * vmalloc space is not orders of magnitude larger than distances
2830 : * between node memory addresses (ie. 32bit NUMA machines).
2831 : *
2832 : * @dyn_size specifies the minimum dynamic area size.
2833 : *
2834 : * If the needed size is smaller than the minimum or specified unit
2835 : * size, the leftover is returned using @free_fn.
2836 : *
2837 : * RETURNS:
2838 : * 0 on success, -errno on failure.
2839 : */
2840 1 : int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
2841 : size_t atom_size,
2842 : pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
2843 : pcpu_fc_alloc_fn_t alloc_fn,
2844 : pcpu_fc_free_fn_t free_fn)
2845 : {
2846 1 : void *base = (void *)ULONG_MAX;
2847 1 : void **areas = NULL;
2848 1 : struct pcpu_alloc_info *ai;
2849 1 : size_t size_sum, areas_size;
2850 1 : unsigned long max_distance;
2851 1 : int group, i, highest_group, rc = 0;
2852 :
2853 1 : ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
2854 : cpu_distance_fn);
2855 1 : if (IS_ERR(ai))
2856 0 : return PTR_ERR(ai);
2857 :
2858 1 : size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2859 1 : areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
2860 :
2861 1 : areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
2862 1 : if (!areas) {
2863 0 : rc = -ENOMEM;
2864 0 : goto out_free;
2865 : }
2866 :
2867 : /* allocate, copy and determine base address & max_distance */
2868 : highest_group = 0;
2869 2 : for (group = 0; group < ai->nr_groups; group++) {
2870 2 : struct pcpu_group_info *gi = &ai->groups[group];
2871 : unsigned int cpu = NR_CPUS;
2872 : void *ptr;
2873 :
2874 2 : for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
2875 1 : cpu = gi->cpu_map[i];
2876 1 : BUG_ON(cpu == NR_CPUS);
2877 :
2878 : /* allocate space for the whole group */
2879 1 : ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
2880 1 : if (!ptr) {
2881 0 : rc = -ENOMEM;
2882 0 : goto out_free_areas;
2883 : }
2884 : /* kmemleak tracks the percpu allocations separately */
2885 1 : kmemleak_free(ptr);
2886 1 : areas[group] = ptr;
2887 :
2888 1 : base = min(ptr, base);
2889 1 : if (ptr > areas[highest_group])
2890 0 : highest_group = group;
2891 : }
2892 1 : max_distance = areas[highest_group] - base;
2893 1 : max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
2894 :
2895 : /* warn if maximum distance is further than 75% of vmalloc space */
2896 1 : if (max_distance > VMALLOC_TOTAL * 3 / 4) {
2897 0 : pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
2898 : max_distance, VMALLOC_TOTAL);
2899 : #ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2900 : /* and fail if we have fallback */
2901 0 : rc = -EINVAL;
2902 0 : goto out_free_areas;
2903 : #endif
2904 : }
2905 :
2906 : /*
2907 : * Copy data and free unused parts. This should happen after all
2908 : * allocations are complete; otherwise, we may end up with
2909 : * overlapping groups.
2910 : */
2911 2 : for (group = 0; group < ai->nr_groups; group++) {
2912 1 : struct pcpu_group_info *gi = &ai->groups[group];
2913 1 : void *ptr = areas[group];
2914 :
2915 5 : for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
2916 4 : if (gi->cpu_map[i] == NR_CPUS) {
2917 : /* unused unit, free whole */
2918 0 : free_fn(ptr, ai->unit_size);
2919 0 : continue;
2920 : }
2921 : /* copy and return the unused part */
2922 4 : memcpy(ptr, __per_cpu_load, ai->static_size);
2923 4 : free_fn(ptr + size_sum, ai->unit_size - size_sum);
2924 : }
2925 : }
2926 :
2927 : /* base address is now known, determine group base offsets */
2928 2 : for (group = 0; group < ai->nr_groups; group++) {
2929 1 : ai->groups[group].base_offset = areas[group] - base;
2930 : }
2931 :
2932 1 : pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
2933 : PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
2934 : ai->dyn_size, ai->unit_size);
2935 :
2936 1 : pcpu_setup_first_chunk(ai, base);
2937 1 : goto out_free;
2938 :
2939 0 : out_free_areas:
2940 0 : for (group = 0; group < ai->nr_groups; group++)
2941 0 : if (areas[group])
2942 0 : free_fn(areas[group],
2943 0 : ai->groups[group].nr_units * ai->unit_size);
2944 0 : out_free:
2945 1 : pcpu_free_alloc_info(ai);
2946 1 : if (areas)
2947 1 : memblock_free_early(__pa(areas), areas_size);
2948 : return rc;
2949 : }
2950 : #endif /* BUILD_EMBED_FIRST_CHUNK */
2951 :
2952 : #ifdef BUILD_PAGE_FIRST_CHUNK
2953 : /**
2954 : * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
2955 : * @reserved_size: the size of reserved percpu area in bytes
2956 : * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
2957 : * @free_fn: function to free percpu page, always called with PAGE_SIZE
2958 : * @populate_pte_fn: function to populate pte
2959 : *
2960 : * This is a helper to ease setting up page-remapped first percpu
2961 : * chunk and can be called where pcpu_setup_first_chunk() is expected.
2962 : *
2963 : * This is the basic allocator. Static percpu area is allocated
2964 : * page-by-page into vmalloc area.
2965 : *
2966 : * RETURNS:
2967 : * 0 on success, -errno on failure.
2968 : */
2969 0 : int __init pcpu_page_first_chunk(size_t reserved_size,
2970 : pcpu_fc_alloc_fn_t alloc_fn,
2971 : pcpu_fc_free_fn_t free_fn,
2972 : pcpu_fc_populate_pte_fn_t populate_pte_fn)
2973 : {
2974 0 : static struct vm_struct vm;
2975 0 : struct pcpu_alloc_info *ai;
2976 0 : char psize_str[16];
2977 0 : int unit_pages;
2978 0 : size_t pages_size;
2979 0 : struct page **pages;
2980 0 : int unit, i, j, rc = 0;
2981 0 : int upa;
2982 0 : int nr_g0_units;
2983 :
2984 0 : snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
2985 :
2986 0 : ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
2987 0 : if (IS_ERR(ai))
2988 0 : return PTR_ERR(ai);
2989 0 : BUG_ON(ai->nr_groups != 1);
2990 0 : upa = ai->alloc_size/ai->unit_size;
2991 0 : nr_g0_units = roundup(num_possible_cpus(), upa);
2992 0 : if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
2993 0 : pcpu_free_alloc_info(ai);
2994 0 : return -EINVAL;
2995 : }
2996 :
2997 0 : unit_pages = ai->unit_size >> PAGE_SHIFT;
2998 :
2999 : /* unaligned allocations can't be freed, round up to page size */
3000 0 : pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
3001 : sizeof(pages[0]));
3002 0 : pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
3003 0 : if (!pages)
3004 0 : panic("%s: Failed to allocate %zu bytes\n", __func__,
3005 : pages_size);
3006 :
3007 : /* allocate pages */
3008 : j = 0;
3009 0 : for (unit = 0; unit < num_possible_cpus(); unit++) {
3010 0 : unsigned int cpu = ai->groups[0].cpu_map[unit];
3011 0 : for (i = 0; i < unit_pages; i++) {
3012 0 : void *ptr;
3013 :
3014 0 : ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
3015 0 : if (!ptr) {
3016 0 : pr_warn("failed to allocate %s page for cpu%u\n",
3017 : psize_str, cpu);
3018 0 : goto enomem;
3019 : }
3020 : /* kmemleak tracks the percpu allocations separately */
3021 0 : kmemleak_free(ptr);
3022 0 : pages[j++] = virt_to_page(ptr);
3023 : }
3024 : }
3025 :
3026 : /* allocate vm area, map the pages and copy static data */
3027 0 : vm.flags = VM_ALLOC;
3028 0 : vm.size = num_possible_cpus() * ai->unit_size;
3029 0 : vm_area_register_early(&vm, PAGE_SIZE);
3030 :
3031 0 : for (unit = 0; unit < num_possible_cpus(); unit++) {
3032 0 : unsigned long unit_addr =
3033 0 : (unsigned long)vm.addr + unit * ai->unit_size;
3034 :
3035 0 : for (i = 0; i < unit_pages; i++)
3036 0 : populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
3037 :
3038 : /* pte already populated, the following shouldn't fail */
3039 0 : rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
3040 : unit_pages);
3041 0 : if (rc < 0)
3042 0 : panic("failed to map percpu area, err=%d\n", rc);
3043 :
3044 : /*
3045 : * FIXME: Archs with virtual cache should flush local
3046 : * cache for the linear mapping here - something
3047 : * equivalent to flush_cache_vmap() on the local cpu.
3048 : * flush_cache_vmap() can't be used as most supporting
3049 : * data structures are not set up yet.
3050 : */
3051 :
3052 : /* copy static data */
3053 0 : memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
3054 : }
3055 :
3056 : /* we're ready, commit */
3057 0 : pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
3058 : unit_pages, psize_str, ai->static_size,
3059 : ai->reserved_size, ai->dyn_size);
3060 :
3061 0 : pcpu_setup_first_chunk(ai, vm.addr);
3062 0 : goto out_free_ar;
3063 :
3064 0 : enomem:
3065 0 : while (--j >= 0)
3066 0 : free_fn(page_address(pages[j]), PAGE_SIZE);
3067 : rc = -ENOMEM;
3068 0 : out_free_ar:
3069 0 : memblock_free_early(__pa(pages), pages_size);
3070 0 : pcpu_free_alloc_info(ai);
3071 0 : return rc;
3072 : }
3073 : #endif /* BUILD_PAGE_FIRST_CHUNK */
3074 :
3075 : #ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
3076 : /*
3077 : * Generic SMP percpu area setup.
3078 : *
3079 : * The embedding helper is used because its behavior closely resembles
3080 : * the original non-dynamic generic percpu area setup. This is
3081 : * important because many archs have addressing restrictions and might
3082 : * fail if the percpu area is located far away from the previous
3083 : * location. As an added bonus, in non-NUMA cases, embedding is
3084 : * generally a good idea TLB-wise because percpu area can piggy back
3085 : * on the physical linear memory mapping which uses large page
3086 : * mappings on applicable archs.
3087 : */
3088 : unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
3089 : EXPORT_SYMBOL(__per_cpu_offset);
3090 :
3091 : static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
3092 : size_t align)
3093 : {
3094 : return memblock_alloc_from(size, align, __pa(MAX_DMA_ADDRESS));
3095 : }
3096 :
3097 : static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
3098 : {
3099 : memblock_free_early(__pa(ptr), size);
3100 : }
3101 :
3102 : void __init setup_per_cpu_areas(void)
3103 : {
3104 : unsigned long delta;
3105 : unsigned int cpu;
3106 : int rc;
3107 :
3108 : /*
3109 : * Always reserve area for module percpu variables. That's
3110 : * what the legacy allocator did.
3111 : */
3112 : rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
3113 : PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
3114 : pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
3115 : if (rc < 0)
3116 : panic("Failed to initialize percpu areas.");
3117 :
3118 : delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
3119 : for_each_possible_cpu(cpu)
3120 : __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
3121 : }
3122 : #endif /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
3123 :
3124 : #else /* CONFIG_SMP */
3125 :
3126 : /*
3127 : * UP percpu area setup.
3128 : *
3129 : * UP always uses km-based percpu allocator with identity mapping.
3130 : * Static percpu variables are indistinguishable from the usual static
3131 : * variables and don't require any special preparation.
3132 : */
3133 : void __init setup_per_cpu_areas(void)
3134 : {
3135 : const size_t unit_size =
3136 : roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
3137 : PERCPU_DYNAMIC_RESERVE));
3138 : struct pcpu_alloc_info *ai;
3139 : void *fc;
3140 :
3141 : ai = pcpu_alloc_alloc_info(1, 1);
3142 : fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3143 : if (!ai || !fc)
3144 : panic("Failed to allocate memory for percpu areas.");
3145 : /* kmemleak tracks the percpu allocations separately */
3146 : kmemleak_free(fc);
3147 :
3148 : ai->dyn_size = unit_size;
3149 : ai->unit_size = unit_size;
3150 : ai->atom_size = unit_size;
3151 : ai->alloc_size = unit_size;
3152 : ai->groups[0].nr_units = 1;
3153 : ai->groups[0].cpu_map[0] = 0;
3154 :
3155 : pcpu_setup_first_chunk(ai, fc);
3156 : pcpu_free_alloc_info(ai);
3157 : }
3158 :
3159 : #endif /* CONFIG_SMP */
3160 :
3161 : /*
3162 : * pcpu_nr_pages - calculate total number of populated backing pages
3163 : *
3164 : * This reflects the number of pages populated to back chunks. Metadata is
3165 : * excluded in the number exposed in meminfo as the number of backing pages
3166 : * scales with the number of cpus and can quickly outweigh the memory used for
3167 : * metadata. It also keeps this calculation nice and simple.
3168 : *
3169 : * RETURNS:
3170 : * Total number of populated backing pages in use by the allocator.
3171 : */
3172 1 : unsigned long pcpu_nr_pages(void)
3173 : {
3174 1 : return pcpu_nr_populated * pcpu_nr_units;
3175 : }
3176 :
3177 : /*
3178 : * Percpu allocator is initialized early during boot when neither slab or
3179 : * workqueue is available. Plug async management until everything is up
3180 : * and running.
3181 : */
3182 1 : static int __init percpu_enable_async(void)
3183 : {
3184 1 : pcpu_async_enabled = true;
3185 1 : return 0;
3186 : }
3187 : subsys_initcall(percpu_enable_async);
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