drivers/base/dma-contiguous.c - arm/linux - Git at Google

 /*
  * Contiguous Memory Allocator for DMA mapping framework
  * Copyright (c) 2010-2011 by Samsung Electronics.
  * Written by:
  *	Marek Szyprowski <m.szyprowski@samsung.com>
  *	Michal Nazarewicz <mina86@mina86.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 <asm/page.h>
 #include <asm/dma-contiguous.h>

 #include <linux/memblock.h>
 #include <linux/err.h>
 #include <linux/mm.h>
 #include <linux/mutex.h>
 #include <linux/page-isolation.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/mm_types.h>
 #include <linux/dma-contiguous.h>

 #ifndef SZ_1M
 #define SZ_1M (1 << 20)
 #endif

 struct cma {
 	unsigned long	base_pfn;
 	unsigned long	count;
 	unsigned long	*bitmap;
 };

 struct cma *dma_contiguous_default_area;

 #ifdef CONFIG_CMA_SIZE_MBYTES
 #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
 #else
 #define CMA_SIZE_MBYTES 0
 #endif

 /*
  * Default global CMA area size can be defined in kernel's .config.
  * This is usefull mainly for distro maintainers to create a kernel
  * that works correctly for most supported systems.
  * The size can be set in bytes or as a percentage of the total memory
  * in the system.
  *
  * Users, who want to set the size of global CMA area for their system
  * should use cma= kernel parameter.
  */
 static const unsigned long size_bytes = CMA_SIZE_MBYTES * SZ_1M;
 static long size_cmdline = -1;

 static int __init early_cma(char *p)
 {
 	pr_debug("%s(%s)\n", __func__, p);
 	size_cmdline = memparse(p, &p);
 	return 0;
 }
 early_param("cma", early_cma);

 #ifdef CONFIG_CMA_SIZE_PERCENTAGE

 static unsigned long __init __maybe_unused cma_early_percent_memory(void)
 {
 	struct memblock_region *reg;
 	unsigned long total_pages = 0;

 	/*
 	 * We cannot use memblock_phys_mem_size() here, because
 	 * memblock_analyze() has not been called yet.
 	 */
 	for_each_memblock(memory, reg)
 		total_pages += memblock_region_memory_end_pfn(reg) -
 			       memblock_region_memory_base_pfn(reg);

 	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
 }

 #else

 static inline __maybe_unused unsigned long cma_early_percent_memory(void)
 {
 	return 0;
 }

 #endif

 /**
  * dma_contiguous_reserve() - reserve area for contiguous memory handling
  * @limit: End address of the reserved memory (optional, 0 for any).
  *
  * 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.
  */
 void __init dma_contiguous_reserve(phys_addr_t limit)
 {
 	unsigned long selected_size = 0;

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

 	if (size_cmdline != -1) {
 		selected_size = size_cmdline;
 	} else {
 #ifdef CONFIG_CMA_SIZE_SEL_MBYTES
 		selected_size = size_bytes;
 #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
 		selected_size = cma_early_percent_memory();
 #elif defined(CONFIG_CMA_SIZE_SEL_MIN)
 		selected_size = min(size_bytes, cma_early_percent_memory());
 #elif defined(CONFIG_CMA_SIZE_SEL_MAX)
 		selected_size = max(size_bytes, cma_early_percent_memory());
 #endif
 	}

 	if (selected_size) {
 		pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 			 selected_size / SZ_1M);

 		dma_declare_contiguous(NULL, selected_size, 0, limit);
 	}
 };

 static DEFINE_MUTEX(cma_mutex);

 static __init int cma_activate_area(unsigned long base_pfn, unsigned long count)
 {
 	unsigned long pfn = base_pfn;
 	unsigned i = count >> pageblock_order;
 	struct zone *zone;

 	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));
 			if (page_zone(pfn_to_page(pfn)) != zone)
 				return -EINVAL;
 		}
 		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
 	} while (--i);
 	return 0;
 }

 static __init struct cma *cma_create_area(unsigned long base_pfn,
 				     unsigned long count)
 {
 	int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
 	struct cma *cma;
 	int ret = -ENOMEM;

 	pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count);

 	cma = kmalloc(sizeof *cma, GFP_KERNEL);
 	if (!cma)
 		return ERR_PTR(-ENOMEM);

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

 	if (!cma->bitmap)
 		goto no_mem;

 	ret = cma_activate_area(base_pfn, count);
 	if (ret)
 		goto error;

 	pr_debug("%s: returned %p\n", __func__, (void *)cma);
 	return cma;

 error:
 	kfree(cma->bitmap);
 no_mem:
 	kfree(cma);
 	return ERR_PTR(ret);
 }

 static struct cma_reserved {
 	phys_addr_t start;
 	unsigned long size;
 	struct device *dev;
 } cma_reserved[MAX_CMA_AREAS] __initdata;
 static unsigned cma_reserved_count __initdata;

 static int __init cma_init_reserved_areas(void)
 {
 	struct cma_reserved *r = cma_reserved;
 	unsigned i = cma_reserved_count;

 	pr_debug("%s()\n", __func__);

 	for (; i; --i, ++r) {
 		struct cma *cma;
 		cma = cma_create_area(PFN_DOWN(r->start),
 				      r->size >> PAGE_SHIFT);
 		if (!IS_ERR(cma))
 			dev_set_cma_area(r->dev, cma);
 	}
 	return 0;
 }
 core_initcall(cma_init_reserved_areas);

 /**
  * dma_declare_contiguous() - reserve area for contiguous memory handling
  *			      for particular device
  * @dev:   Pointer to device structure.
  * @size:  Size of the reserved memory.
  * @base:  Start address of the reserved memory (optional, 0 for any).
  * @limit: End address of the reserved memory (optional, 0 for any).
  *
  * This function reserves memory for specified device. It should be
  * called by board specific code when early allocator (memblock or bootmem)
  * is still activate.
  */
 int __init dma_declare_contiguous(struct device *dev, unsigned long size,
 				  phys_addr_t base, phys_addr_t limit)
 {
 	struct cma_reserved *r = &cma_reserved[cma_reserved_count];
 	unsigned long alignment;

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

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

 	if (!size)
 		return -EINVAL;

 	/* Sanitise input arguments */
 	alignment = PAGE_SIZE << max(MAX_ORDER, pageblock_order);
 	base = ALIGN(base, alignment);
 	size = ALIGN(size, alignment);
 	limit &= ~(alignment - 1);

 	/* Reserve memory */
 	if (base) {
 		if (memblock_is_region_reserved(base, size) ||
 		    memblock_reserve(base, size) < 0) {
 			base = -EBUSY;
 			goto err;
 		}
 	} else {
 		/*
 		 * Use __memblock_alloc_base() since
 		 * memblock_alloc_base() panic()s.
 		 */
 		phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
 		if (!addr) {
 			base = -ENOMEM;
 			goto err;
 		} else if (addr + size > ~(unsigned long)0) {
 			memblock_free(addr, size);
 			base = -EINVAL;
 			goto err;
 		} else {
 			base = addr;
 		}
 	}

 	/*
 	 * Each reserved area must be initialised later, when more kernel
 	 * subsystems (like slab allocator) are available.
 	 */
 	r->start = base;
 	r->size = size;
 	r->dev = dev;
 	cma_reserved_count++;
 	pr_info("CMA: reserved %ld MiB at %08lx\n", size / SZ_1M,
 		(unsigned long)base);

 	/* Architecture specific contiguous memory fixup. */
 	dma_contiguous_early_fixup(base, size);
 	return 0;
 err:
 	pr_err("CMA: failed to reserve %ld MiB\n", size / SZ_1M);
 	return base;
 }

 /**
  * dma_alloc_from_contiguous() - allocate pages from contiguous area
  * @dev:   Pointer to device for which the allocation is performed.
  * @count: Requested number of pages.
  * @align: Requested alignment of pages (in PAGE_SIZE order).
  *
  * This function allocates memory buffer for specified device. It uses
  * device specific contiguous memory area if available or the default
  * global one. Requires architecture specific get_dev_cma_area() helper
  * function.
  */
 struct page *dma_alloc_from_contiguous(struct device *dev, int count,
 				       unsigned int align)
 {
 	unsigned long mask, pfn, pageno, start = 0;
 	struct cma *cma = dev_get_cma_area(dev);
 	int ret;

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

 	if (align > CONFIG_CMA_ALIGNMENT)
 		align = CONFIG_CMA_ALIGNMENT;

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

 	if (!count)
 		return NULL;

 	mask = (1 << align) - 1;

 	mutex_lock(&cma_mutex);

 	for (;;) {
 		pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
 						    start, count, mask);
 		if (pageno >= cma->count) {
 			ret = -ENOMEM;
 			goto error;
 		}

 		pfn = cma->base_pfn + pageno;
 		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
 		if (ret == 0) {
 			bitmap_set(cma->bitmap, pageno, count);
 			break;
 		} else if (ret != -EBUSY) {
 			goto error;
 		}
 		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 = pageno + mask + 1;
 	}

 	mutex_unlock(&cma_mutex);

 	pr_debug("%s(): returned %p\n", __func__, pfn_to_page(pfn));
 	return pfn_to_page(pfn);
 error:
 	mutex_unlock(&cma_mutex);
 	return NULL;
 }

 /**
  * dma_release_from_contiguous() - release allocated pages
  * @dev:   Pointer to device for which the pages were allocated.
  * @pages: Allocated pages.
  * @count: Number of allocated pages.
  *
  * This function releases memory allocated by dma_alloc_from_contiguous().
  * It returns false when provided pages do not belong to contiguous area and
  * true otherwise.
  */
 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
 				 int count)
 {
 	struct cma *cma = dev_get_cma_area(dev);
 	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);

 	mutex_lock(&cma_mutex);
 	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
 	free_contig_range(pfn, count);
 	mutex_unlock(&cma_mutex);

 	return true;
 }
	/*
	* Contiguous Memory Allocator for DMA mapping framework
	* Copyright (c) 2010-2011 by Samsung Electronics.
	* Written by:
	* Marek Szyprowski <m.szyprowski@samsung.com>
	* Michal Nazarewicz <mina86@mina86.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 <asm/page.h>
	#include <asm/dma-contiguous.h>

	#include <linux/memblock.h>
	#include <linux/err.h>
	#include <linux/mm.h>
	#include <linux/mutex.h>
	#include <linux/page-isolation.h>
	#include <linux/slab.h>
	#include <linux/swap.h>
	#include <linux/mm_types.h>
	#include <linux/dma-contiguous.h>

	#ifndef SZ_1M
	#define SZ_1M (1 << 20)
	#endif

	struct cma {
	unsigned long base_pfn;
	unsigned long count;
	unsigned long *bitmap;
	};

	struct cma *dma_contiguous_default_area;

	#ifdef CONFIG_CMA_SIZE_MBYTES
	#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
	#else
	#define CMA_SIZE_MBYTES 0
	#endif

	/*
	* Default global CMA area size can be defined in kernel's .config.
	* This is usefull mainly for distro maintainers to create a kernel
	* that works correctly for most supported systems.
	* The size can be set in bytes or as a percentage of the total memory
	* in the system.
	*
	* Users, who want to set the size of global CMA area for their system
	* should use cma= kernel parameter.
	*/
	static const unsigned long size_bytes = CMA_SIZE_MBYTES * SZ_1M;
	static long size_cmdline = -1;

	static int __init early_cma(char *p)
	{
	pr_debug("%s(%s)\n", __func__, p);
	size_cmdline = memparse(p, &p);
	return 0;
	}
	early_param("cma", early_cma);

	#ifdef CONFIG_CMA_SIZE_PERCENTAGE

	static unsigned long __init __maybe_unused cma_early_percent_memory(void)
	{
	struct memblock_region *reg;
	unsigned long total_pages = 0;

	/*
	* We cannot use memblock_phys_mem_size() here, because
	* memblock_analyze() has not been called yet.
	*/
	for_each_memblock(memory, reg)
	total_pages += memblock_region_memory_end_pfn(reg) -
	memblock_region_memory_base_pfn(reg);

	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
	}

	#else

	static inline __maybe_unused unsigned long cma_early_percent_memory(void)
	{
	return 0;
	}

	#endif

	/**
	* dma_contiguous_reserve() - reserve area for contiguous memory handling
	* @limit: End address of the reserved memory (optional, 0 for any).
	*
	* 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.
	*/
	void __init dma_contiguous_reserve(phys_addr_t limit)
	{
	unsigned long selected_size = 0;

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

	if (size_cmdline != -1) {
	selected_size = size_cmdline;
	} else {
	#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
	selected_size = size_bytes;
	#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
	selected_size = cma_early_percent_memory();
	#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
	selected_size = min(size_bytes, cma_early_percent_memory());
	#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
	selected_size = max(size_bytes, cma_early_percent_memory());
	#endif
	}

	if (selected_size) {
	pr_debug("%s: reserving %ld MiB for global area\n", __func__,
	selected_size / SZ_1M);

	dma_declare_contiguous(NULL, selected_size, 0, limit);
	}
	};

	static DEFINE_MUTEX(cma_mutex);

	static __init int cma_activate_area(unsigned long base_pfn, unsigned long count)
	{
	unsigned long pfn = base_pfn;
	unsigned i = count >> pageblock_order;
	struct zone *zone;

	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));
	if (page_zone(pfn_to_page(pfn)) != zone)
	return -EINVAL;
	}
	init_cma_reserved_pageblock(pfn_to_page(base_pfn));
	} while (--i);
	return 0;
	}

	static __init struct cma *cma_create_area(unsigned long base_pfn,
	unsigned long count)
	{
	int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
	struct cma *cma;
	int ret = -ENOMEM;

	pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count);

	cma = kmalloc(sizeof *cma, GFP_KERNEL);
	if (!cma)
	return ERR_PTR(-ENOMEM);

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

	if (!cma->bitmap)
	goto no_mem;

	ret = cma_activate_area(base_pfn, count);
	if (ret)
	goto error;

	pr_debug("%s: returned %p\n", __func__, (void *)cma);
	return cma;

	error:
	kfree(cma->bitmap);
	no_mem:
	kfree(cma);
	return ERR_PTR(ret);
	}

	static struct cma_reserved {
	phys_addr_t start;
	unsigned long size;
	struct device *dev;
	} cma_reserved[MAX_CMA_AREAS] __initdata;
	static unsigned cma_reserved_count __initdata;

	static int __init cma_init_reserved_areas(void)
	{
	struct cma_reserved *r = cma_reserved;
	unsigned i = cma_reserved_count;

	pr_debug("%s()\n", __func__);

	for (; i; --i, ++r) {
	struct cma *cma;
	cma = cma_create_area(PFN_DOWN(r->start),
	r->size >> PAGE_SHIFT);
	if (!IS_ERR(cma))
	dev_set_cma_area(r->dev, cma);
	}
	return 0;
	}
	core_initcall(cma_init_reserved_areas);

	/**
	* dma_declare_contiguous() - reserve area for contiguous memory handling
	* for particular device
	* @dev: Pointer to device structure.
	* @size: Size of the reserved memory.
	* @base: Start address of the reserved memory (optional, 0 for any).
	* @limit: End address of the reserved memory (optional, 0 for any).
	*
	* This function reserves memory for specified device. It should be
	* called by board specific code when early allocator (memblock or bootmem)
	* is still activate.
	*/
	int __init dma_declare_contiguous(struct device *dev, unsigned long size,
	phys_addr_t base, phys_addr_t limit)
	{
	struct cma_reserved *r = &cma_reserved[cma_reserved_count];
	unsigned long alignment;

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

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

	if (!size)
	return -EINVAL;

	/* Sanitise input arguments */
	alignment = PAGE_SIZE << max(MAX_ORDER, pageblock_order);
	base = ALIGN(base, alignment);
	size = ALIGN(size, alignment);
	limit &= ~(alignment - 1);

	/* Reserve memory */
	if (base) {
	if (memblock_is_region_reserved(base, size) \|\|
	memblock_reserve(base, size) < 0) {
	base = -EBUSY;
	goto err;
	}
	} else {
	/*
	* Use __memblock_alloc_base() since
	* memblock_alloc_base() panic()s.
	*/
	phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
	if (!addr) {
	base = -ENOMEM;
	goto err;
	} else if (addr + size > ~(unsigned long)0) {
	memblock_free(addr, size);
	base = -EINVAL;
	goto err;
	} else {
	base = addr;
	}
	}

	/*
	* Each reserved area must be initialised later, when more kernel
	* subsystems (like slab allocator) are available.
	*/
	r->start = base;
	r->size = size;
	r->dev = dev;
	cma_reserved_count++;
	pr_info("CMA: reserved %ld MiB at %08lx\n", size / SZ_1M,
	(unsigned long)base);

	/* Architecture specific contiguous memory fixup. */
	dma_contiguous_early_fixup(base, size);
	return 0;
	err:
	pr_err("CMA: failed to reserve %ld MiB\n", size / SZ_1M);
	return base;
	}

	/**
	* dma_alloc_from_contiguous() - allocate pages from contiguous area
	* @dev: Pointer to device for which the allocation is performed.
	* @count: Requested number of pages.
	* @align: Requested alignment of pages (in PAGE_SIZE order).
	*
	* This function allocates memory buffer for specified device. It uses
	* device specific contiguous memory area if available or the default
	* global one. Requires architecture specific get_dev_cma_area() helper
	* function.
	*/
	struct page dma_alloc_from_contiguous(struct device dev, int count,
	unsigned int align)
	{
	unsigned long mask, pfn, pageno, start = 0;
	struct cma *cma = dev_get_cma_area(dev);
	int ret;

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

	if (align > CONFIG_CMA_ALIGNMENT)
	align = CONFIG_CMA_ALIGNMENT;

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

	if (!count)
	return NULL;

	mask = (1 << align) - 1;

	mutex_lock(&cma_mutex);

	for (;;) {
	pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
	start, count, mask);
	if (pageno >= cma->count) {
	ret = -ENOMEM;
	goto error;
	}

	pfn = cma->base_pfn + pageno;
	ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
	if (ret == 0) {
	bitmap_set(cma->bitmap, pageno, count);
	break;
	} else if (ret != -EBUSY) {
	goto error;
	}
	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 = pageno + mask + 1;
	}

	mutex_unlock(&cma_mutex);

	pr_debug("%s(): returned %p\n", __func__, pfn_to_page(pfn));
	return pfn_to_page(pfn);
	error:
	mutex_unlock(&cma_mutex);
	return NULL;
	}

	/**
	* dma_release_from_contiguous() - release allocated pages
	* @dev: Pointer to device for which the pages were allocated.
	* @pages: Allocated pages.
	* @count: Number of allocated pages.
	*
	* This function releases memory allocated by dma_alloc_from_contiguous().
	* It returns false when provided pages do not belong to contiguous area and
	* true otherwise.
	*/
	bool dma_release_from_contiguous(struct device dev, struct page pages,
	int count)
	{
	struct cma *cma = dev_get_cma_area(dev);
	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);

	mutex_lock(&cma_mutex);
	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
	free_contig_range(pfn, count);
	mutex_unlock(&cma_mutex);

	return true;
	}