[mirror_ubuntu-zesty-kernel.git] / mm / cma.c

/*
 * Contiguous Memory Allocator
 *
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Copyright IBM Corporation, 2013
 * Copyright LG Electronics Inc., 2014
 * Written by:
 *	Marek Szyprowski <m.szyprowski@samsung.com>
 *	Michal Nazarewicz <mina86@mina86.com>
 *	Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
 *	Joonsoo Kim <iamjoonsoo.kim@lge.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License or (at your optional) any later version of the license.
 */

#define pr_fmt(fmt) "cma: " fmt

#ifdef CONFIG_CMA_DEBUG
#ifndef DEBUG
#  define DEBUG
#endif
#endif

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/log2.h>
#include <linux/cma.h>
#include <linux/highmem.h>

struct cma {
	unsigned long	base_pfn;
	unsigned long	count;
	unsigned long	*bitmap;
	unsigned int order_per_bit; /* Order of pages represented by one bit */
	struct mutex	lock;
};

static struct cma cma_areas[MAX_CMA_AREAS];
static unsigned cma_area_count;
static DEFINE_MUTEX(cma_mutex);

phys_addr_t cma_get_base(struct cma *cma)
{
	return PFN_PHYS(cma->base_pfn);
}

unsigned long cma_get_size(struct cma *cma)
{
	return cma->count << PAGE_SHIFT;
}

static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
{
	if (align_order <= cma->order_per_bit)
		return 0;
	return (1UL << (align_order - cma->order_per_bit)) - 1;
}

static unsigned long cma_bitmap_maxno(struct cma *cma)
{
	return cma->count >> cma->order_per_bit;
}

static unsigned long cma_bitmap_pages_to_bits(struct cma *cma,
						unsigned long pages)
{
	return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
}

static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count)
{
	unsigned long bitmap_no, bitmap_count;

	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
	bitmap_count = cma_bitmap_pages_to_bits(cma, count);

	mutex_lock(&cma->lock);
	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
	mutex_unlock(&cma->lock);
}

static int __init cma_activate_area(struct cma *cma)
{
	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
	unsigned i = cma->count >> pageblock_order;
	struct zone *zone;

	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);

	if (!cma->bitmap)
		return -ENOMEM;

	WARN_ON_ONCE(!pfn_valid(pfn));
	zone = page_zone(pfn_to_page(pfn));

	do {
		unsigned j;

		base_pfn = pfn;
		for (j = pageblock_nr_pages; j; --j, pfn++) {
			WARN_ON_ONCE(!pfn_valid(pfn));
			/*
			 * alloc_contig_range requires the pfn range
			 * specified to be in the same zone. Make this
			 * simple by forcing the entire CMA resv range
			 * to be in the same zone.
			 */
			if (page_zone(pfn_to_page(pfn)) != zone)
				goto err;
		}
		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
	} while (--i);

	mutex_init(&cma->lock);
	return 0;

err:
	kfree(cma->bitmap);
	cma->count = 0;
	return -EINVAL;
}

static int __init cma_init_reserved_areas(void)
{
	int i;

	for (i = 0; i < cma_area_count; i++) {
		int ret = cma_activate_area(&cma_areas[i]);

		if (ret)
			return ret;
	}

	return 0;
}
core_initcall(cma_init_reserved_areas);

/**
 * cma_init_reserved_mem() - create custom contiguous area from reserved memory
 * @base: Base address of the reserved area
 * @size: Size of the reserved area (in bytes),
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @res_cma: Pointer to store the created cma region.
 *
 * This function creates custom contiguous area from already reserved memory.
 */
int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
				 int order_per_bit, struct cma **res_cma)
{
	struct cma *cma;
	phys_addr_t alignment;

	/* Sanity checks */
	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
		pr_err("Not enough slots for CMA reserved regions!\n");
		return -ENOSPC;
	}

	if (!size || !memblock_is_region_reserved(base, size))
		return -EINVAL;

	/* ensure minimal alignment requied by mm core */
	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);

	/* alignment should be aligned with order_per_bit */
	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
		return -EINVAL;

	if (ALIGN(base, alignment) != base || ALIGN(size, alignment) != size)
		return -EINVAL;

	/*
	 * Each reserved area must be initialised later, when more kernel
	 * subsystems (like slab allocator) are available.
	 */
	cma = &cma_areas[cma_area_count];
	cma->base_pfn = PFN_DOWN(base);
	cma->count = size >> PAGE_SHIFT;
	cma->order_per_bit = order_per_bit;
	*res_cma = cma;
	cma_area_count++;

	return 0;
}

/**
 * cma_declare_contiguous() - reserve custom contiguous area
 * @base: Base address of the reserved area optional, use 0 for any
 * @size: Size of the reserved area (in bytes),
 * @limit: End address of the reserved memory (optional, 0 for any).
 * @alignment: Alignment for the CMA area, should be power of 2 or zero
 * @order_per_bit: Order of pages represented by one bit on bitmap.
 * @fixed: hint about where to place the reserved area
 * @res_cma: Pointer to store the created cma region.
 *
 * This function reserves memory from early allocator. It should be
 * called by arch specific code once the early allocator (memblock or bootmem)
 * has been activated and all other subsystems have already allocated/reserved
 * memory. This function allows to create custom reserved areas.
 *
 * If @fixed is true, reserve contiguous area at exactly @base.  If false,
 * reserve in range from @base to @limit.
 */
int __init cma_declare_contiguous(phys_addr_t base,
			phys_addr_t size, phys_addr_t limit,
			phys_addr_t alignment, unsigned int order_per_bit,
			bool fixed, struct cma **res_cma)
{
	phys_addr_t memblock_end = memblock_end_of_DRAM();
	phys_addr_t highmem_start = __pa(high_memory);
	int ret = 0;

	pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
		__func__, (unsigned long)size, (unsigned long)base,
		(unsigned long)limit, (unsigned long)alignment);

	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
		pr_err("Not enough slots for CMA reserved regions!\n");
		return -ENOSPC;
	}

	if (!size)
		return -EINVAL;

	if (alignment && !is_power_of_2(alignment))
		return -EINVAL;

	/*
	 * Sanitise input arguments.
	 * Pages both ends in CMA area could be merged into adjacent unmovable
	 * migratetype page by page allocator's buddy algorithm. In the case,
	 * you couldn't get a contiguous memory, which is not what we want.
	 */
	alignment = max(alignment,
		(phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
	base = ALIGN(base, alignment);
	size = ALIGN(size, alignment);
	limit &= ~(alignment - 1);

	/* size should be aligned with order_per_bit */
	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
		return -EINVAL;

	/*
	 * adjust limit to avoid crossing low/high memory boundary for
	 * automatically allocated regions
	 */
	if (((limit == 0 || limit > memblock_end) &&
	     (memblock_end - size < highmem_start &&
	      memblock_end > highmem_start)) ||
	    (!fixed && limit > highmem_start && limit - size < highmem_start)) {
		limit = highmem_start;
	}

	if (fixed && base < highmem_start && base+size > highmem_start) {
		ret = -EINVAL;
		pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n",
			(unsigned long)base, (unsigned long)highmem_start);
		goto err;
	}

	/* Reserve memory */
	if (base && fixed) {
		if (memblock_is_region_reserved(base, size) ||
		    memblock_reserve(base, size) < 0) {
			ret = -EBUSY;
			goto err;
		}
	} else {
		phys_addr_t addr = memblock_alloc_range(size, alignment, base,
							limit);
		if (!addr) {
			ret = -ENOMEM;
			goto err;
		} else {
			base = addr;
		}
	}

	ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
	if (ret)
		goto err;

	pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
		(unsigned long)base);
	return 0;

err:
	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
	return ret;
}

/**
 * cma_alloc() - allocate pages from contiguous area
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @count: Requested number of pages.
 * @align: Requested alignment of pages (in PAGE_SIZE order).
 *
 * This function allocates part of contiguous memory on specific
 * contiguous memory area.
 */
struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
{
	unsigned long mask, pfn, start = 0;
	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
	struct page *page = NULL;
	int ret;

	if (!cma || !cma->count)
		return NULL;

	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
		 count, align);

	if (!count)
		return NULL;

	mask = cma_bitmap_aligned_mask(cma, align);
	bitmap_maxno = cma_bitmap_maxno(cma);
	bitmap_count = cma_bitmap_pages_to_bits(cma, count);

	for (;;) {
		mutex_lock(&cma->lock);
		bitmap_no = bitmap_find_next_zero_area(cma->bitmap,
				bitmap_maxno, start, bitmap_count, mask);
		if (bitmap_no >= bitmap_maxno) {
			mutex_unlock(&cma->lock);
			break;
		}
		bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
		/*
		 * It's safe to drop the lock here. We've marked this region for
		 * our exclusive use. If the migration fails we will take the
		 * lock again and unmark it.
		 */
		mutex_unlock(&cma->lock);

		pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
		mutex_lock(&cma_mutex);
		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
		mutex_unlock(&cma_mutex);
		if (ret == 0) {
			page = pfn_to_page(pfn);
			break;
		}

		cma_clear_bitmap(cma, pfn, count);
		if (ret != -EBUSY)
			break;

		pr_debug("%s(): memory range at %p is busy, retrying\n",
			 __func__, pfn_to_page(pfn));
		/* try again with a bit different memory target */
		start = bitmap_no + mask + 1;
	}

	pr_debug("%s(): returned %p\n", __func__, page);
	return page;
}

/**
 * cma_release() - release allocated pages
 * @cma:   Contiguous memory region for which the allocation is performed.
 * @pages: Allocated pages.
 * @count: Number of allocated pages.
 *
 * This function releases memory allocated by alloc_cma().
 * It returns false when provided pages do not belong to contiguous area and
 * true otherwise.
 */
bool cma_release(struct cma *cma, struct page *pages, int count)
{
	unsigned long pfn;

	if (!cma || !pages)
		return false;

	pr_debug("%s(page %p)\n", __func__, (void *)pages);

	pfn = page_to_pfn(pages);

	if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
		return false;

	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);

	free_contig_range(pfn, count);
	cma_clear_bitmap(cma, pfn, count);

	return true;
}
Commit	Line	Data
a254129e JK	1	/*
	2	* Contiguous Memory Allocator
	3	*
	4	* Copyright (c) 2010-2011 by Samsung Electronics.
	5	* Copyright IBM Corporation, 2013
	6	* Copyright LG Electronics Inc., 2014
	7	* Written by:
	8	* Marek Szyprowski <m.szyprowski@samsung.com>
	9	* Michal Nazarewicz <mina86@mina86.com>
	10	* Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
	11	* Joonsoo Kim <iamjoonsoo.kim@lge.com>
	12	*
	13	* This program is free software; you can redistribute it and/or
	14	* modify it under the terms of the GNU General Public License as
	15	* published by the Free Software Foundation; either version 2 of the
	16	* License or (at your optional) any later version of the license.
	17	*/
	18
	19	#define pr_fmt(fmt) "cma: " fmt
	20
	21	#ifdef CONFIG_CMA_DEBUG
	22	#ifndef DEBUG
	23	# define DEBUG
	24	#endif
	25	#endif
	26
	27	#include <linux/memblock.h>
	28	#include <linux/err.h>
	29	#include <linux/mm.h>
	30	#include <linux/mutex.h>
	31	#include <linux/sizes.h>
	32	#include <linux/slab.h>
	33	#include <linux/log2.h>
	34	#include <linux/cma.h>
f7426b98	35	#include <linux/highmem.h>
a254129e JK	36
	37	struct cma {
	38	unsigned long base_pfn;
	39	unsigned long count;
	40	unsigned long *bitmap;
	41	unsigned int order_per_bit; /* Order of pages represented by one bit */
	42	struct mutex lock;
	43	};
	44
	45	static struct cma cma_areas[MAX_CMA_AREAS];
	46	static unsigned cma_area_count;
	47	static DEFINE_MUTEX(cma_mutex);
	48
	49	phys_addr_t cma_get_base(struct cma *cma)
	50	{
	51	return PFN_PHYS(cma->base_pfn);
	52	}
	53
	54	unsigned long cma_get_size(struct cma *cma)
	55	{
	56	return cma->count << PAGE_SHIFT;
	57	}
	58
	59	static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
	60	{
68faed63 WY	61	if (align_order <= cma->order_per_bit)
	62	return 0;
	63	return (1UL << (align_order - cma->order_per_bit)) - 1;
a254129e JK	64	}
	65
	66	static unsigned long cma_bitmap_maxno(struct cma *cma)
	67	{
	68	return cma->count >> cma->order_per_bit;
	69	}
	70
	71	static unsigned long cma_bitmap_pages_to_bits(struct cma *cma,
	72	unsigned long pages)
	73	{
	74	return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit;
	75	}
	76
	77	static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count)
	78	{
	79	unsigned long bitmap_no, bitmap_count;
	80
	81	bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit;
	82	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
	83
	84	mutex_lock(&cma->lock);
	85	bitmap_clear(cma->bitmap, bitmap_no, bitmap_count);
	86	mutex_unlock(&cma->lock);
	87	}
	88
	89	static int __init cma_activate_area(struct cma *cma)
	90	{
	91	int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long);
	92	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
	93	unsigned i = cma->count >> pageblock_order;
	94	struct zone *zone;
	95
	96	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
	97
	98	if (!cma->bitmap)
	99	return -ENOMEM;
	100
	101	WARN_ON_ONCE(!pfn_valid(pfn));
	102	zone = page_zone(pfn_to_page(pfn));
	103
	104	do {
	105	unsigned j;
	106
	107	base_pfn = pfn;
	108	for (j = pageblock_nr_pages; j; --j, pfn++) {
	109	WARN_ON_ONCE(!pfn_valid(pfn));
	110	/*
	111	* alloc_contig_range requires the pfn range
	112	* specified to be in the same zone. Make this
	113	* simple by forcing the entire CMA resv range
	114	* to be in the same zone.
	115	*/
	116	if (page_zone(pfn_to_page(pfn)) != zone)
	117	goto err;
	118	}
	119	init_cma_reserved_pageblock(pfn_to_page(base_pfn));
	120	} while (--i);
	121
	122	mutex_init(&cma->lock);
	123	return 0;
	124
	125	err:
	126	kfree(cma->bitmap);
f022d8cb	127	cma->count = 0;
a254129e JK	128	return -EINVAL;
	129	}
	130
	131	static int __init cma_init_reserved_areas(void)
	132	{
	133	int i;
	134
	135	for (i = 0; i < cma_area_count; i++) {
	136	int ret = cma_activate_area(&cma_areas[i]);
	137
	138	if (ret)
	139	return ret;
	140	}
	141
	142	return 0;
	143	}
	144	core_initcall(cma_init_reserved_areas);
	145
de9e14ee MS	146	/**
	147	* cma_init_reserved_mem() - create custom contiguous area from reserved memory
	148	* @base: Base address of the reserved area
	149	* @size: Size of the reserved area (in bytes),
	150	* @order_per_bit: Order of pages represented by one bit on bitmap.
	151	* @res_cma: Pointer to store the created cma region.
	152	*
	153	* This function creates custom contiguous area from already reserved memory.
	154	*/
	155	int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
	156	int order_per_bit, struct cma **res_cma)
	157	{
	158	struct cma *cma;
	159	phys_addr_t alignment;
	160
	161	/* Sanity checks */
	162	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
	163	pr_err("Not enough slots for CMA reserved regions!\n");
	164	return -ENOSPC;
	165	}
	166
	167	if (!size \|\| !memblock_is_region_reserved(base, size))
	168	return -EINVAL;
	169
	170	/* ensure minimal alignment requied by mm core */
	171	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
	172
	173	/* alignment should be aligned with order_per_bit */
	174	if (!IS_ALIGNED(alignment >> PAGE_SHIFT, 1 << order_per_bit))
	175	return -EINVAL;
	176
	177	if (ALIGN(base, alignment) != base \|\| ALIGN(size, alignment) != size)
	178	return -EINVAL;
	179
	180	/*
	181	* Each reserved area must be initialised later, when more kernel
	182	* subsystems (like slab allocator) are available.
	183	*/
	184	cma = &cma_areas[cma_area_count];
	185	cma->base_pfn = PFN_DOWN(base);
	186	cma->count = size >> PAGE_SHIFT;
	187	cma->order_per_bit = order_per_bit;
	188	*res_cma = cma;
	189	cma_area_count++;
	190
	191	return 0;
	192	}
	193
a254129e JK	194	/**
a254129e JK	195	* cma_declare_contiguous() - reserve custom contiguous area
a254129e	196	* @base: Base address of the reserved area optional, use 0 for any
c1f733aa	197	* @size: Size of the reserved area (in bytes),
a254129e JK	198	* @limit: End address of the reserved memory (optional, 0 for any).
	199	* @alignment: Alignment for the CMA area, should be power of 2 or zero
	200	* @order_per_bit: Order of pages represented by one bit on bitmap.
a254129e	201	* @fixed: hint about where to place the reserved area
c1f733aa	202	* @res_cma: Pointer to store the created cma region.
a254129e JK	203	*
	204	* This function reserves memory from early allocator. It should be
	205	* called by arch specific code once the early allocator (memblock or bootmem)
	206	* has been activated and all other subsystems have already allocated/reserved
	207	* memory. This function allows to create custom reserved areas.
	208	*
	209	* If @fixed is true, reserve contiguous area at exactly @base. If false,
	210	* reserve in range from @base to @limit.
	211	*/
c1f733aa JK	212	int __init cma_declare_contiguous(phys_addr_t base,
c1f733aa JK	213	phys_addr_t size, phys_addr_t limit,
a254129e	214	phys_addr_t alignment, unsigned int order_per_bit,
c1f733aa	215	bool fixed, struct cma **res_cma)
a254129e	216	{
f7426b98 MS	217	phys_addr_t memblock_end = memblock_end_of_DRAM();
f7426b98 MS	218	phys_addr_t highmem_start = __pa(high_memory);
a254129e JK	219	int ret = 0;
	220
	221	pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
	222	__func__, (unsigned long)size, (unsigned long)base,
	223	(unsigned long)limit, (unsigned long)alignment);
	224
	225	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
	226	pr_err("Not enough slots for CMA reserved regions!\n");
	227	return -ENOSPC;
	228	}
	229
	230	if (!size)
	231	return -EINVAL;
	232
	233	if (alignment && !is_power_of_2(alignment))
	234	return -EINVAL;
	235
	236	/*
	237	* Sanitise input arguments.
	238	* Pages both ends in CMA area could be merged into adjacent unmovable
	239	* migratetype page by page allocator's buddy algorithm. In the case,
	240	* you couldn't get a contiguous memory, which is not what we want.
	241	*/
	242	alignment = max(alignment,
	243	(phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order));
	244	base = ALIGN(base, alignment);
	245	size = ALIGN(size, alignment);
	246	limit &= ~(alignment - 1);
	247
	248	/* size should be aligned with order_per_bit */
	249	if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
	250	return -EINVAL;
	251
f7426b98 MS	252	/*
	253	* adjust limit to avoid crossing low/high memory boundary for
	254	* automatically allocated regions
	255	*/
	256	if (((limit == 0 \|\| limit > memblock_end) &&
	257	(memblock_end - size < highmem_start &&
	258	memblock_end > highmem_start)) \|\|
	259	(!fixed && limit > highmem_start && limit - size < highmem_start)) {
	260	limit = highmem_start;
	261	}
	262
	263	if (fixed && base < highmem_start && base+size > highmem_start) {
	264	ret = -EINVAL;
	265	pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n",
	266	(unsigned long)base, (unsigned long)highmem_start);
	267	goto err;
	268	}
	269
a254129e JK	270	/* Reserve memory */
	271	if (base && fixed) {
	272	if (memblock_is_region_reserved(base, size) \|\|
	273	memblock_reserve(base, size) < 0) {
	274	ret = -EBUSY;
	275	goto err;
	276	}
	277	} else {
	278	phys_addr_t addr = memblock_alloc_range(size, alignment, base,
	279	limit);
	280	if (!addr) {
	281	ret = -ENOMEM;
	282	goto err;
	283	} else {
	284	base = addr;
	285	}
	286	}
	287
de9e14ee MS	288	ret = cma_init_reserved_mem(base, size, order_per_bit, res_cma);
	289	if (ret)
	290	goto err;
a254129e	291
0de9d2eb	292	pr_info("Reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
a254129e JK	293	(unsigned long)base);
	294	return 0;
	295
	296	err:
0de9d2eb	297	pr_err("Failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
a254129e JK	298	return ret;
	299	}
	300
	301	/**
	302	* cma_alloc() - allocate pages from contiguous area
	303	* @cma: Contiguous memory region for which the allocation is performed.
	304	* @count: Requested number of pages.
	305	* @align: Requested alignment of pages (in PAGE_SIZE order).
	306	*
	307	* This function allocates part of contiguous memory on specific
	308	* contiguous memory area.
	309	*/
	310	struct page cma_alloc(struct cma cma, int count, unsigned int align)
	311	{
	312	unsigned long mask, pfn, start = 0;
	313	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
	314	struct page *page = NULL;
	315	int ret;
	316
	317	if (!cma \|\| !cma->count)
	318	return NULL;
	319
	320	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
	321	count, align);
	322
	323	if (!count)
	324	return NULL;
	325
	326	mask = cma_bitmap_aligned_mask(cma, align);
	327	bitmap_maxno = cma_bitmap_maxno(cma);
	328	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
	329
	330	for (;;) {
	331	mutex_lock(&cma->lock);
	332	bitmap_no = bitmap_find_next_zero_area(cma->bitmap,
	333	bitmap_maxno, start, bitmap_count, mask);
	334	if (bitmap_no >= bitmap_maxno) {
	335	mutex_unlock(&cma->lock);
	336	break;
	337	}
	338	bitmap_set(cma->bitmap, bitmap_no, bitmap_count);
	339	/*
	340	* It's safe to drop the lock here. We've marked this region for
	341	* our exclusive use. If the migration fails we will take the
	342	* lock again and unmark it.
	343	*/
	344	mutex_unlock(&cma->lock);
	345
	346	pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit);
	347	mutex_lock(&cma_mutex);
	348	ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
	349	mutex_unlock(&cma_mutex);
	350	if (ret == 0) {
	351	page = pfn_to_page(pfn);
	352	break;
a254129e	353	}
b7155e76	354
a254129e	355	cma_clear_bitmap(cma, pfn, count);
b7155e76 JK	356	if (ret != -EBUSY)
	357	break;
	358
a254129e JK	359	pr_debug("%s(): memory range at %p is busy, retrying\n",
	360	__func__, pfn_to_page(pfn));
	361	/* try again with a bit different memory target */
	362	start = bitmap_no + mask + 1;
	363	}
	364
	365	pr_debug("%s(): returned %p\n", __func__, page);
	366	return page;
	367	}
	368
	369	/**
	370	* cma_release() - release allocated pages
	371	* @cma: Contiguous memory region for which the allocation is performed.
	372	* @pages: Allocated pages.
	373	* @count: Number of allocated pages.
	374	*
	375	* This function releases memory allocated by alloc_cma().
	376	* It returns false when provided pages do not belong to contiguous area and
	377	* true otherwise.
	378	*/
	379	bool cma_release(struct cma cma, struct page pages, int count)
	380	{
	381	unsigned long pfn;
	382
	383	if (!cma \|\| !pages)
	384	return false;
	385
	386	pr_debug("%s(page %p)\n", __func__, (void *)pages);
	387
	388	pfn = page_to_pfn(pages);
	389
	390	if (pfn < cma->base_pfn \|\| pfn >= cma->base_pfn + cma->count)
	391	return false;
	392
	393	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
	394
	395	free_contig_range(pfn, count);
	396	cma_clear_bitmap(cma, pfn, count);
	397
	398	return true;
	399	}