1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Contiguous Memory Allocator
5 * Copyright (c) 2010-2011 by Samsung Electronics.
6 * Copyright IBM Corporation, 2013
7 * Copyright LG Electronics Inc., 2014
9 * Marek Szyprowski <m.szyprowski@samsung.com>
10 * Michal Nazarewicz <mina86@mina86.com>
11 * Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
12 * Joonsoo Kim <iamjoonsoo.kim@lge.com>
15 #define pr_fmt(fmt) "cma: " fmt
17 #ifdef CONFIG_CMA_DEBUG
22 #define CREATE_TRACE_POINTS
24 #include <linux/memblock.h>
25 #include <linux/err.h>
27 #include <linux/mutex.h>
28 #include <linux/sizes.h>
29 #include <linux/slab.h>
30 #include <linux/log2.h>
31 #include <linux/cma.h>
32 #include <linux/highmem.h>
34 #include <linux/kmemleak.h>
35 #include <trace/events/cma.h>
39 struct cma cma_areas[MAX_CMA_AREAS];
40 unsigned cma_area_count;
42 phys_addr_t cma_get_base(const struct cma *cma)
44 return PFN_PHYS(cma->base_pfn);
47 unsigned long cma_get_size(const struct cma *cma)
49 return cma->count << PAGE_SHIFT;
52 const char *cma_get_name(const struct cma *cma)
57 static unsigned long cma_bitmap_aligned_mask(const struct cma *cma,
58 unsigned int align_order)
60 if (align_order <= cma->order_per_bit)
62 return (1UL << (align_order - cma->order_per_bit)) - 1;
66 * Find the offset of the base PFN from the specified align_order.
67 * The value returned is represented in order_per_bits.
69 static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
70 unsigned int align_order)
72 return (cma->base_pfn & ((1UL << align_order) - 1))
73 >> cma->order_per_bit;
76 static unsigned long cma_bitmap_pages_to_bits(const struct cma *cma,
79 return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
82 static void cma_clear_bitmap(struct cma *cma, unsigned long pfn,
85 unsigned long bitmap_no, bitmap_count;
87 bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
88 bitmap_count = cma_bitmap_pages_to_bits(cma, count);
90 mutex_lock(&cma->lock);
91 bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
92 mutex_unlock(&cma->lock);
95 static void __init cma_activate_area(struct cma *cma)
97 unsigned long base_pfn = cma->base_pfn, pfn;
100 cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
105 * alloc_contig_range() requires the pfn range specified to be in the
106 * same zone. Simplify by forcing the entire CMA resv range to be in the
109 WARN_ON_ONCE(!pfn_valid(base_pfn));
110 zone = page_zone(pfn_to_page(base_pfn));
111 for (pfn = base_pfn + 1; pfn < base_pfn + cma->count; pfn++) {
112 WARN_ON_ONCE(!pfn_valid(pfn));
113 if (page_zone(pfn_to_page(pfn)) != zone)
117 for (pfn = base_pfn; pfn < base_pfn + cma->count;
118 pfn += pageblock_nr_pages)
119 init_cma_reserved_pageblock(pfn_to_page(pfn));
121 mutex_init(&cma->lock);
123 #ifdef CONFIG_CMA_DEBUGFS
124 INIT_HLIST_HEAD(&cma->mem_head);
125 spin_lock_init(&cma->mem_head_lock);
131 bitmap_free(cma->bitmap);
133 /* Expose all pages to the buddy, they are useless for CMA. */
134 for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
135 free_reserved_page(pfn_to_page(pfn));
136 totalcma_pages -= cma->count;
138 pr_err("CMA area %s could not be activated\n", cma->name);
142 static int __init cma_init_reserved_areas(void)
146 for (i = 0; i < cma_area_count; i++)
147 cma_activate_area(&cma_areas[i]);
151 core_initcall(cma_init_reserved_areas);
154 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
155 * @base: Base address of the reserved area
156 * @size: Size of the reserved area (in bytes),
157 * @order_per_bit: Order of pages represented by one bit on bitmap.
158 * @name: The name of the area. If this parameter is NULL, the name of
159 * the area will be set to "cmaN", where N is a running counter of
161 * @res_cma: Pointer to store the created cma region.
163 * This function creates custom contiguous area from already reserved memory.
165 int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
166 unsigned int order_per_bit,
168 struct cma **res_cma)
171 phys_addr_t alignment;
174 if (cma_area_count == ARRAY_SIZE(cma_areas)) {
175 pr_err("Not enough slots for CMA reserved regions!\n");
179 if (!size || !memblock_is_region_reserved(base, size))
182 /* ensure minimal alignment required by mm core */
183 alignment = PAGE_SIZE <<
184 max_t(unsigned long, MAX_ORDER - 1, pageblock_order);
186 /* alignment should be aligned with order_per_bit */
187 if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
190 if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
194 * Each reserved area must be initialised later, when more kernel
195 * subsystems (like slab allocator) are available.
197 cma = &cma_areas[cma_area_count];
200 snprintf(cma->name, CMA_MAX_NAME, name);
202 snprintf(cma->name, CMA_MAX_NAME, "cma%d\n", cma_area_count);
204 cma->base_pfn = PFN_DOWN(base);
205 cma->count = size >> PAGE_SHIFT;
206 cma->order_per_bit = order_per_bit;
209 totalcma_pages += (size / PAGE_SIZE);
215 * cma_declare_contiguous_nid() - reserve custom contiguous area
216 * @base: Base address of the reserved area optional, use 0 for any
217 * @size: Size of the reserved area (in bytes),
218 * @limit: End address of the reserved memory (optional, 0 for any).
219 * @alignment: Alignment for the CMA area, should be power of 2 or zero
220 * @order_per_bit: Order of pages represented by one bit on bitmap.
221 * @fixed: hint about where to place the reserved area
222 * @name: The name of the area. See function cma_init_reserved_mem()
223 * @res_cma: Pointer to store the created cma region.
224 * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
226 * This function reserves memory from early allocator. It should be
227 * called by arch specific code once the early allocator (memblock or bootmem)
228 * has been activated and all other subsystems have already allocated/reserved
229 * memory. This function allows to create custom reserved areas.
231 * If @fixed is true, reserve contiguous area at exactly @base. If false,
232 * reserve in range from @base to @limit.
234 int __init cma_declare_contiguous_nid(phys_addr_t base,
235 phys_addr_t size, phys_addr_t limit,
236 phys_addr_t alignment, unsigned int order_per_bit,
237 bool fixed, const char *name, struct cma **res_cma,
240 phys_addr_t memblock_end = memblock_end_of_DRAM();
241 phys_addr_t highmem_start;
245 * We can't use __pa(high_memory) directly, since high_memory
246 * isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
247 * complain. Find the boundary by adding one to the last valid
250 highmem_start = __pa(high_memory - 1) + 1;
251 pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
252 __func__, &size, &base, &limit, &alignment);
254 if (cma_area_count == ARRAY_SIZE(cma_areas)) {
255 pr_err("Not enough slots for CMA reserved regions!\n");
262 if (alignment && !is_power_of_2(alignment))
266 * Sanitise input arguments.
267 * Pages both ends in CMA area could be merged into adjacent unmovable
268 * migratetype page by page allocator's buddy algorithm. In the case,
269 * you couldn't get a contiguous memory, which is not what we want.
271 alignment = max(alignment, (phys_addr_t)PAGE_SIZE <<
272 max_t(unsigned long, MAX_ORDER - 1, pageblock_order));
273 if (fixed && base & (alignment - 1)) {
275 pr_err("Region at %pa must be aligned to %pa bytes\n",
279 base = ALIGN(base, alignment);
280 size = ALIGN(size, alignment);
281 limit &= ~(alignment - 1);
286 /* size should be aligned with order_per_bit */
287 if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
291 * If allocating at a fixed base the request region must not cross the
292 * low/high memory boundary.
294 if (fixed && base < highmem_start && base + size > highmem_start) {
296 pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
297 &base, &highmem_start);
302 * If the limit is unspecified or above the memblock end, its effective
303 * value will be the memblock end. Set it explicitly to simplify further
306 if (limit == 0 || limit > memblock_end)
307 limit = memblock_end;
309 if (base + size > limit) {
311 pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
312 &size, &base, &limit);
318 if (memblock_is_region_reserved(base, size) ||
319 memblock_reserve(base, size) < 0) {
324 phys_addr_t addr = 0;
327 * All pages in the reserved area must come from the same zone.
328 * If the requested region crosses the low/high memory boundary,
329 * try allocating from high memory first and fall back to low
330 * memory in case of failure.
332 if (base < highmem_start && limit > highmem_start) {
333 addr = memblock_alloc_range_nid(size, alignment,
334 highmem_start, limit, nid, true);
335 limit = highmem_start;
339 * If there is enough memory, try a bottom-up allocation first.
340 * It will place the new cma area close to the start of the node
341 * and guarantee that the compaction is moving pages out of the
342 * cma area and not into it.
343 * Avoid using first 4GB to not interfere with constrained zones
346 #ifdef CONFIG_PHYS_ADDR_T_64BIT
347 if (!memblock_bottom_up() && memblock_end >= SZ_4G + size) {
348 memblock_set_bottom_up(true);
349 addr = memblock_alloc_range_nid(size, alignment, SZ_4G,
351 memblock_set_bottom_up(false);
356 addr = memblock_alloc_range_nid(size, alignment, base,
365 * kmemleak scans/reads tracked objects for pointers to other
366 * objects but this address isn't mapped and accessible
368 kmemleak_ignore_phys(addr);
372 ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
376 pr_info("Reserved %ld MiB at %pa\n", (unsigned long)size / SZ_1M,
381 memblock_free(base, size);
383 pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
387 #ifdef CONFIG_CMA_DEBUG
388 static void cma_debug_show_areas(struct cma *cma)
390 unsigned long next_zero_bit, next_set_bit, nr_zero;
391 unsigned long start = 0;
392 unsigned long nr_part, nr_total = 0;
393 unsigned long nbits = cma_bitmap_maxno(cma);
395 mutex_lock(&cma->lock);
396 pr_info("number of available pages: ");
398 next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start);
399 if (next_zero_bit >= nbits)
401 next_set_bit = find_next_bit(cma->bitmap, nbits, next_zero_bit);
402 nr_zero = next_set_bit - next_zero_bit;
403 nr_part = nr_zero << cma->order_per_bit;
404 pr_cont("%s%lu@%lu", nr_total ? "+" : "", nr_part,
407 start = next_zero_bit + nr_zero;
409 pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count);
410 mutex_unlock(&cma->lock);
413 static inline void cma_debug_show_areas(struct cma *cma) { }
417 * cma_alloc() - allocate pages from contiguous area
418 * @cma: Contiguous memory region for which the allocation is performed.
419 * @count: Requested number of pages.
420 * @align: Requested alignment of pages (in PAGE_SIZE order).
421 * @no_warn: Avoid printing message about failed allocation
423 * This function allocates part of contiguous memory on specific
424 * contiguous memory area.
426 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
429 unsigned long mask, offset;
430 unsigned long pfn = -1;
431 unsigned long start = 0;
432 unsigned long bitmap_maxno, bitmap_no, bitmap_count;
434 struct page *page = NULL;
437 if (!cma || !cma->count || !cma->bitmap)
440 pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
446 mask = cma_bitmap_aligned_mask(cma, align);
447 offset = cma_bitmap_aligned_offset(cma, align);
448 bitmap_maxno = cma_bitmap_maxno(cma);
449 bitmap_count = cma_bitmap_pages_to_bits(cma, count);
451 if (bitmap_count > bitmap_maxno)
455 mutex_lock(&cma->lock);
456 bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
457 bitmap_maxno, start, bitmap_count, mask,
459 if (bitmap_no >= bitmap_maxno) {
460 mutex_unlock(&cma->lock);
463 bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
465 * It's safe to drop the lock here. We've marked this region for
466 * our exclusive use. If the migration fails we will take the
467 * lock again and unmark it.
469 mutex_unlock(&cma->lock);
471 pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
472 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA,
473 GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0));
476 page = pfn_to_page(pfn);
480 cma_clear_bitmap(cma, pfn, count);
484 pr_debug("%s(): memory range at %p is busy, retrying\n",
485 __func__, pfn_to_page(pfn));
486 /* try again with a bit different memory target */
487 start = bitmap_no + mask + 1;
490 trace_cma_alloc(pfn, page, count, align);
493 * CMA can allocate multiple page blocks, which results in different
494 * blocks being marked with different tags. Reset the tags to ignore
498 for (i = 0; i < count; i++)
499 page_kasan_tag_reset(page + i);
502 if (ret && !no_warn) {
503 pr_err("%s: %s: alloc failed, req-size: %zu pages, ret: %d\n",
504 __func__, cma->name, count, ret);
505 cma_debug_show_areas(cma);
508 pr_debug("%s(): returned %p\n", __func__, page);
513 * cma_release() - release allocated pages
514 * @cma: Contiguous memory region for which the allocation is performed.
515 * @pages: Allocated pages.
516 * @count: Number of allocated pages.
518 * This function releases memory allocated by cma_alloc().
519 * It returns false when provided pages do not belong to contiguous area and
522 bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
529 pr_debug("%s(page %p, count %u)\n", __func__, (void *)pages, count);
531 pfn = page_to_pfn(pages);
533 if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
536 VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
538 free_contig_range(pfn, count);
539 cma_clear_bitmap(cma, pfn, count);
540 trace_cma_release(pfn, pages, count);
545 int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
549 for (i = 0; i < cma_area_count; i++) {
550 int ret = it(&cma_areas[i], data);