mm/cma.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * 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>
  */

 #define pr_fmt(fmt) "cma: " fmt

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

 #include <linux/memblock.h>
 #include <linux/err.h>
 #include <linux/mm.h>
 #include <linux/module.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>
 #include <linux/io.h>
 #include <linux/kmemleak.h>
 #include <linux/sched.h>
 #include <linux/jiffies.h>
 #include <trace/events/cma.h>

 #undef CREATE_TRACE_POINTS
 #include <trace/hooks/mm.h>

 #include "cma.h"

 struct cma cma_areas[MAX_CMA_AREAS];
 unsigned cma_area_count;

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

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

 const char *cma_get_name(const struct cma *cma)
 {
 	return cma->name;
 }
 EXPORT_SYMBOL_GPL(cma_get_name);

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

 /*
  * Find the offset of the base PFN from the specified align_order.
  * The value returned is represented in order_per_bits.
  */
 static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
 					       unsigned int align_order)
 {
 	return (cma->base_pfn & ((1UL << align_order) - 1))
 		>> cma->order_per_bit;
 }

 static unsigned long cma_bitmap_pages_to_bits(const 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,
 			     unsigned 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 void __init cma_activate_area(struct cma *cma)
 {
 	unsigned long base_pfn = cma->base_pfn, pfn;
 	struct zone *zone;

 	cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
 	if (!cma->bitmap)
 		goto out_error;

 	/*
 	 * alloc_contig_range() requires the pfn range specified to be in the
 	 * same zone. Simplify by forcing the entire CMA resv range to be in the
 	 * same zone.
 	 */
 	WARN_ON_ONCE(!pfn_valid(base_pfn));
 	zone = page_zone(pfn_to_page(base_pfn));
 	for (pfn = base_pfn + 1; pfn < base_pfn + cma->count; pfn++) {
 		WARN_ON_ONCE(!pfn_valid(pfn));
 		if (page_zone(pfn_to_page(pfn)) != zone)
 			goto not_in_zone;
 	}

 	for (pfn = base_pfn; pfn < base_pfn + cma->count;
 	     pfn += pageblock_nr_pages)
 		init_cma_reserved_pageblock(pfn_to_page(pfn));

 	mutex_init(&cma->lock);

 #ifdef CONFIG_CMA_DEBUGFS
 	INIT_HLIST_HEAD(&cma->mem_head);
 	spin_lock_init(&cma->mem_head_lock);
 #endif

 	return;

 not_in_zone:
 	bitmap_free(cma->bitmap);
 out_error:
 	/* Expose all pages to the buddy, they are useless for CMA. */
 	for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
 		free_reserved_page(pfn_to_page(pfn));
 	totalcma_pages -= cma->count;
 	cma->count = 0;
 	pr_err("CMA area %s could not be activated\n", cma->name);
 	return;
 }

 static int __init cma_init_reserved_areas(void)
 {
 	int i;

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

 	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.
  * @name: The name of the area. If this parameter is NULL, the name of
  *        the area will be set to "cmaN", where N is a running counter of
  *        used areas.
  * @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,
 				 unsigned int order_per_bit,
 				 const char *name,
 				 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 required by mm core */
 	alignment = PAGE_SIZE <<
 			max_t(unsigned long, 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];

 	if (name)
 		snprintf(cma->name, CMA_MAX_NAME, name);
 	else
 		snprintf(cma->name, CMA_MAX_NAME,  "cma%d\n", 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++;
 	totalcma_pages += (size / PAGE_SIZE);

 	return 0;
 }

 /**
  * cma_declare_contiguous_nid() - 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
  * @name: The name of the area. See function cma_init_reserved_mem()
  * @res_cma: Pointer to store the created cma region.
  * @nid: nid of the free area to find, %NUMA_NO_NODE for any node
  *
  * 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_nid(phys_addr_t base,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
 			int nid)
 {
 	phys_addr_t memblock_end = memblock_end_of_DRAM();
 	phys_addr_t highmem_start;
 	int ret = 0;

 	/*
 	 * We can't use __pa(high_memory) directly, since high_memory
 	 * isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
 	 * complain. Find the boundary by adding one to the last valid
 	 * address.
 	 */
 	highmem_start = __pa(high_memory - 1) + 1;
 	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
 		__func__, &size, &base, &limit, &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_t(unsigned long, MAX_ORDER - 1, pageblock_order));
 	if (fixed && base & (alignment - 1)) {
 		ret = -EINVAL;
 		pr_err("Region at %pa must be aligned to %pa bytes\n",
 			&base, &alignment);
 		goto err;
 	}
 	base = ALIGN(base, alignment);
 	size = ALIGN(size, alignment);
 	limit &= ~(alignment - 1);

 	if (!base)
 		fixed = false;

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

 	/*
 	 * If allocating at a fixed base the request region must not cross the
 	 * low/high memory boundary.
 	 */
 	if (fixed && base < highmem_start && base + size > highmem_start) {
 		ret = -EINVAL;
 		pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
 			&base, &highmem_start);
 		goto err;
 	}

 	/*
 	 * If the limit is unspecified or above the memblock end, its effective
 	 * value will be the memblock end. Set it explicitly to simplify further
 	 * checks.
 	 */
 	if (limit == 0 || limit > memblock_end)
 		limit = memblock_end;

 	if (base + size > limit) {
 		ret = -EINVAL;
 		pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
 			&size, &base, &limit);
 		goto err;
 	}

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

 		/*
 		 * All pages in the reserved area must come from the same zone.
 		 * If the requested region crosses the low/high memory boundary,
 		 * try allocating from high memory first and fall back to low
 		 * memory in case of failure.
 		 */
 		if (base < highmem_start && limit > highmem_start) {
 			addr = memblock_alloc_range_nid(size, alignment,
 					highmem_start, limit, nid, true);
 			limit = highmem_start;
 		}

 		/*
 		 * If there is enough memory, try a bottom-up allocation first.
 		 * It will place the new cma area close to the start of the node
 		 * and guarantee that the compaction is moving pages out of the
 		 * cma area and not into it.
 		 * Avoid using first 4GB to not interfere with constrained zones
 		 * like DMA/DMA32.
 		 */
 #ifdef CONFIG_PHYS_ADDR_T_64BIT
 		if (!memblock_bottom_up() && memblock_end >= SZ_4G + size) {
 			memblock_set_bottom_up(true);
 			addr = memblock_alloc_range_nid(size, alignment, SZ_4G,
 							limit, nid, true);
 			memblock_set_bottom_up(false);
 		}
 #endif

 		if (!addr) {
 			addr = memblock_alloc_range_nid(size, alignment, base,
 					limit, nid, true);
 			if (!addr) {
 				ret = -ENOMEM;
 				goto err;
 			}
 		}

 		/*
 		 * kmemleak scans/reads tracked objects for pointers to other
 		 * objects but this address isn't mapped and accessible
 		 */
 		kmemleak_ignore_phys(addr);
 		base = addr;
 	}

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

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

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

 #ifdef CONFIG_CMA_DEBUG
 static void cma_debug_show_areas(struct cma *cma)
 {
 	unsigned long next_zero_bit, next_set_bit, nr_zero;
 	unsigned long start = 0;
 	unsigned long nr_part, nr_total = 0;
 	unsigned long nbits = cma_bitmap_maxno(cma);

 	mutex_lock(&cma->lock);
 	pr_info("number of available pages: ");
 	for (;;) {
 		next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start);
 		if (next_zero_bit >= nbits)
 			break;
 		next_set_bit = find_next_bit(cma->bitmap, nbits, next_zero_bit);
 		nr_zero = next_set_bit - next_zero_bit;
 		nr_part = nr_zero << cma->order_per_bit;
 		pr_cont("%s%lu@%lu", nr_total ? "+" : "", nr_part,
 			next_zero_bit);
 		nr_total += nr_part;
 		start = next_zero_bit + nr_zero;
 	}
 	pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count);
 	mutex_unlock(&cma->lock);
 }
 #else
 static inline void cma_debug_show_areas(struct cma *cma) { }
 #endif

 /**
  * 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).
  * @gfp_mask: GFP mask to use during the cma allocation.
  *
  * This function allocates part of contiguous memory on specific
  * contiguous memory area.
  */
 struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
 		       gfp_t gfp_mask)
 {
 	unsigned long mask, offset;
 	unsigned long pfn = -1;
 	unsigned long start = 0;
 	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
 	size_t i;
 	struct page *page = NULL;
 	int ret = -ENOMEM;
 	int num_attempts = 0;
 	int max_retries = 5;
 	s64 ts;
 	struct cma_alloc_info cma_info = {0};

 	trace_android_vh_cma_alloc_start(&ts);

 	if (!cma || !cma->count || !cma->bitmap)
 		goto out;

 	pr_debug("%s(cma %p, count %zu, align %d gfp_mask 0x%x)\n", __func__,
 			(void *)cma, count, align, gfp_mask);

 	if (!count)
 		goto out;

 	trace_cma_alloc_start(cma->name, count, align);

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

 	if (bitmap_count > bitmap_maxno)
 		goto out;

 	for (;;) {
 		struct acr_info info = {0};

 		mutex_lock(&cma->lock);
 		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
 				bitmap_maxno, start, bitmap_count, mask,
 				offset);
 		if (bitmap_no >= bitmap_maxno) {
 			if ((num_attempts < max_retries) && (ret == -EBUSY)) {
 				mutex_unlock(&cma->lock);

 				if (fatal_signal_pending(current) ||
 				    (gfp_mask & __GFP_NORETRY))
 					break;

 				/*
 				 * Page may be momentarily pinned by some other
 				 * process which has been scheduled out, e.g.
 				 * in exit path, during unmap call, or process
 				 * fork and so cannot be freed there. Sleep
 				 * for 100ms and retry the allocation.
 				 */
 				start = 0;
 				ret = -ENOMEM;
 				schedule_timeout_killable(msecs_to_jiffies(100));
 				num_attempts++;
 				continue;
 			} else {
 				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);
 		ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, gfp_mask, &info);
 		cma_info.nr_migrated += info.nr_migrated;
 		cma_info.nr_reclaimed += info.nr_reclaimed;
 		cma_info.nr_mapped += info.nr_mapped;
 		if (info.err) {
 			if (info.err & ACR_ERR_ISOLATE)
 				cma_info.nr_isolate_fail++;
 			if (info.err & ACR_ERR_MIGRATE)
 				cma_info.nr_migrate_fail++;
 			if (info.err & ACR_ERR_TEST)
 				cma_info.nr_test_fail++;
 		}
 		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));

 		trace_android_vh_cma_alloc_busy_info(&info);
 		trace_cma_alloc_busy_retry(cma->name, pfn, pfn_to_page(pfn),
 					   count, align);

 		if (info.failed_pfn && gfp_mask & __GFP_NORETRY) {
 			/* try again from following failed page */
 			start = (pfn_max_align_up(info.failed_pfn + 1) -
 				 cma->base_pfn) >> cma->order_per_bit;

 		} else {
 			/* try again with a bit different memory target */
 			start = bitmap_no + mask + 1;
 		}
 	}

 	trace_cma_alloc_finish(cma->name, pfn, page, count, align);
 	trace_cma_alloc_info(cma->name, page, count, align, &cma_info);

 	/*
 	 * CMA can allocate multiple page blocks, which results in different
 	 * blocks being marked with different tags. Reset the tags to ignore
 	 * those page blocks.
 	 */
 	if (page) {
 		for (i = 0; i < count; i++)
 			page_kasan_tag_reset(page + i);
 	}

 	if (ret && !(gfp_mask & __GFP_NOWARN)) {
 		pr_err("%s: %s: alloc failed, req-size: %zu pages, ret: %d\n",
 		       __func__, cma->name, count, ret);
 		cma_debug_show_areas(cma);
 	}

 	pr_debug("%s(): returned %p\n", __func__, page);
 out:
 	trace_android_vh_cma_alloc_finish(cma, page, count, align, gfp_mask, ts);
 	if (page) {
 		count_vm_event(CMA_ALLOC_SUCCESS);
 		cma_sysfs_account_success_pages(cma, count);
 	} else if (!(gfp_mask & __GFP_NORETRY)) {
 		count_vm_event(CMA_ALLOC_FAIL);
 		if (cma)
 			cma_sysfs_account_fail_pages(cma, count);
 	}

 	return page;
 }
 EXPORT_SYMBOL_GPL(cma_alloc);

 /**
  * 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 cma_alloc().
  * It returns false when provided pages do not belong to contiguous area and
  * true otherwise.
  */
 bool cma_release(struct cma *cma, const struct page *pages, unsigned int count)
 {
 	unsigned long pfn;

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

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

 	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);
 	trace_cma_release(cma->name, pfn, pages, count);

 	return true;
 }
 EXPORT_SYMBOL_GPL(cma_release);

 int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
 {
 	int i;

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

 		if (ret)
 			return ret;
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(cma_for_each_area);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* 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>
	*/

	#define pr_fmt(fmt) "cma: " fmt

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

	#include <linux/memblock.h>
	#include <linux/err.h>
	#include <linux/mm.h>
	#include <linux/module.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>
	#include <linux/io.h>
	#include <linux/kmemleak.h>
	#include <linux/sched.h>
	#include <linux/jiffies.h>
	#include <trace/events/cma.h>

	#undef CREATE_TRACE_POINTS
	#include <trace/hooks/mm.h>

	#include "cma.h"

	struct cma cma_areas[MAX_CMA_AREAS];
	unsigned cma_area_count;

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

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

	const char cma_get_name(const struct cma cma)
	{
	return cma->name;
	}
	EXPORT_SYMBOL_GPL(cma_get_name);

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

	/*
	* Find the offset of the base PFN from the specified align_order.
	* The value returned is represented in order_per_bits.
	*/
	static unsigned long cma_bitmap_aligned_offset(const struct cma *cma,
	unsigned int align_order)
	{
	return (cma->base_pfn & ((1UL << align_order) - 1))
	>> cma->order_per_bit;
	}

	static unsigned long cma_bitmap_pages_to_bits(const 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,
	unsigned 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 void __init cma_activate_area(struct cma *cma)
	{
	unsigned long base_pfn = cma->base_pfn, pfn;
	struct zone *zone;

	cma->bitmap = bitmap_zalloc(cma_bitmap_maxno(cma), GFP_KERNEL);
	if (!cma->bitmap)
	goto out_error;

	/*
	* alloc_contig_range() requires the pfn range specified to be in the
	* same zone. Simplify by forcing the entire CMA resv range to be in the
	* same zone.
	*/
	WARN_ON_ONCE(!pfn_valid(base_pfn));
	zone = page_zone(pfn_to_page(base_pfn));
	for (pfn = base_pfn + 1; pfn < base_pfn + cma->count; pfn++) {
	WARN_ON_ONCE(!pfn_valid(pfn));
	if (page_zone(pfn_to_page(pfn)) != zone)
	goto not_in_zone;
	}

	for (pfn = base_pfn; pfn < base_pfn + cma->count;
	pfn += pageblock_nr_pages)
	init_cma_reserved_pageblock(pfn_to_page(pfn));

	mutex_init(&cma->lock);

	#ifdef CONFIG_CMA_DEBUGFS
	INIT_HLIST_HEAD(&cma->mem_head);
	spin_lock_init(&cma->mem_head_lock);
	#endif

	return;

	not_in_zone:
	bitmap_free(cma->bitmap);
	out_error:
	/* Expose all pages to the buddy, they are useless for CMA. */
	for (pfn = base_pfn; pfn < base_pfn + cma->count; pfn++)
	free_reserved_page(pfn_to_page(pfn));
	totalcma_pages -= cma->count;
	cma->count = 0;
	pr_err("CMA area %s could not be activated\n", cma->name);
	return;
	}

	static int __init cma_init_reserved_areas(void)
	{
	int i;

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

	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.
	* @name: The name of the area. If this parameter is NULL, the name of
	* the area will be set to "cmaN", where N is a running counter of
	* used areas.
	* @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,
	unsigned int order_per_bit,
	const char *name,
	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 required by mm core */
	alignment = PAGE_SIZE <<
	max_t(unsigned long, 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];

	if (name)
	snprintf(cma->name, CMA_MAX_NAME, name);
	else
	snprintf(cma->name, CMA_MAX_NAME, "cma%d\n", 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++;
	totalcma_pages += (size / PAGE_SIZE);

	return 0;
	}

	/**
	* cma_declare_contiguous_nid() - 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
	* @name: The name of the area. See function cma_init_reserved_mem()
	* @res_cma: Pointer to store the created cma region.
	* @nid: nid of the free area to find, %NUMA_NO_NODE for any node
	*
	* 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_nid(phys_addr_t base,
	phys_addr_t size, phys_addr_t limit,
	phys_addr_t alignment, unsigned int order_per_bit,
	bool fixed, const char name, struct cma *res_cma,
	int nid)
	{
	phys_addr_t memblock_end = memblock_end_of_DRAM();
	phys_addr_t highmem_start;
	int ret = 0;

	/*
	* We can't use __pa(high_memory) directly, since high_memory
	* isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
	* complain. Find the boundary by adding one to the last valid
	* address.
	*/
	highmem_start = __pa(high_memory - 1) + 1;
	pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
	__func__, &size, &base, &limit, &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_t(unsigned long, MAX_ORDER - 1, pageblock_order));
	if (fixed && base & (alignment - 1)) {
	ret = -EINVAL;
	pr_err("Region at %pa must be aligned to %pa bytes\n",
	&base, &alignment);
	goto err;
	}
	base = ALIGN(base, alignment);
	size = ALIGN(size, alignment);
	limit &= ~(alignment - 1);

	if (!base)
	fixed = false;

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

	/*
	* If allocating at a fixed base the request region must not cross the
	* low/high memory boundary.
	*/
	if (fixed && base < highmem_start && base + size > highmem_start) {
	ret = -EINVAL;
	pr_err("Region at %pa defined on low/high memory boundary (%pa)\n",
	&base, &highmem_start);
	goto err;
	}

	/*
	* If the limit is unspecified or above the memblock end, its effective
	* value will be the memblock end. Set it explicitly to simplify further
	* checks.
	*/
	if (limit == 0 \|\| limit > memblock_end)
	limit = memblock_end;

	if (base + size > limit) {
	ret = -EINVAL;
	pr_err("Size (%pa) of region at %pa exceeds limit (%pa)\n",
	&size, &base, &limit);
	goto err;
	}

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

	/*
	* All pages in the reserved area must come from the same zone.
	* If the requested region crosses the low/high memory boundary,
	* try allocating from high memory first and fall back to low
	* memory in case of failure.
	*/
	if (base < highmem_start && limit > highmem_start) {
	addr = memblock_alloc_range_nid(size, alignment,
	highmem_start, limit, nid, true);
	limit = highmem_start;
	}

	/*
	* If there is enough memory, try a bottom-up allocation first.
	* It will place the new cma area close to the start of the node
	* and guarantee that the compaction is moving pages out of the
	* cma area and not into it.
	* Avoid using first 4GB to not interfere with constrained zones
	* like DMA/DMA32.
	*/
	#ifdef CONFIG_PHYS_ADDR_T_64BIT
	if (!memblock_bottom_up() && memblock_end >= SZ_4G + size) {
	memblock_set_bottom_up(true);
	addr = memblock_alloc_range_nid(size, alignment, SZ_4G,
	limit, nid, true);
	memblock_set_bottom_up(false);
	}
	#endif

	if (!addr) {
	addr = memblock_alloc_range_nid(size, alignment, base,
	limit, nid, true);
	if (!addr) {
	ret = -ENOMEM;
	goto err;
	}
	}

	/*
	* kmemleak scans/reads tracked objects for pointers to other
	* objects but this address isn't mapped and accessible
	*/
	kmemleak_ignore_phys(addr);
	base = addr;
	}

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

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

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

	#ifdef CONFIG_CMA_DEBUG
	static void cma_debug_show_areas(struct cma *cma)
	{
	unsigned long next_zero_bit, next_set_bit, nr_zero;
	unsigned long start = 0;
	unsigned long nr_part, nr_total = 0;
	unsigned long nbits = cma_bitmap_maxno(cma);

	mutex_lock(&cma->lock);
	pr_info("number of available pages: ");
	for (;;) {
	next_zero_bit = find_next_zero_bit(cma->bitmap, nbits, start);
	if (next_zero_bit >= nbits)
	break;
	next_set_bit = find_next_bit(cma->bitmap, nbits, next_zero_bit);
	nr_zero = next_set_bit - next_zero_bit;
	nr_part = nr_zero << cma->order_per_bit;
	pr_cont("%s%lu@%lu", nr_total ? "+" : "", nr_part,
	next_zero_bit);
	nr_total += nr_part;
	start = next_zero_bit + nr_zero;
	}
	pr_cont("=> %lu free of %lu total pages\n", nr_total, cma->count);
	mutex_unlock(&cma->lock);
	}
	#else
	static inline void cma_debug_show_areas(struct cma *cma) { }
	#endif

	/**
	* 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).
	* @gfp_mask: GFP mask to use during the cma allocation.
	*
	* This function allocates part of contiguous memory on specific
	* contiguous memory area.
	*/
	struct page cma_alloc(struct cma cma, size_t count, unsigned int align,
	gfp_t gfp_mask)
	{
	unsigned long mask, offset;
	unsigned long pfn = -1;
	unsigned long start = 0;
	unsigned long bitmap_maxno, bitmap_no, bitmap_count;
	size_t i;
	struct page *page = NULL;
	int ret = -ENOMEM;
	int num_attempts = 0;
	int max_retries = 5;
	s64 ts;
	struct cma_alloc_info cma_info = {0};

	trace_android_vh_cma_alloc_start(&ts);

	if (!cma \|\| !cma->count \|\| !cma->bitmap)
	goto out;

	pr_debug("%s(cma %p, count %zu, align %d gfp_mask 0x%x)\n", __func__,
	(void *)cma, count, align, gfp_mask);

	if (!count)
	goto out;

	trace_cma_alloc_start(cma->name, count, align);

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

	if (bitmap_count > bitmap_maxno)
	goto out;

	for (;;) {
	struct acr_info info = {0};

	mutex_lock(&cma->lock);
	bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
	bitmap_maxno, start, bitmap_count, mask,
	offset);
	if (bitmap_no >= bitmap_maxno) {
	if ((num_attempts < max_retries) && (ret == -EBUSY)) {
	mutex_unlock(&cma->lock);

	if (fatal_signal_pending(current) \|\|
	(gfp_mask & __GFP_NORETRY))
	break;

	/*
	* Page may be momentarily pinned by some other
	* process which has been scheduled out, e.g.
	* in exit path, during unmap call, or process
	* fork and so cannot be freed there. Sleep
	* for 100ms and retry the allocation.
	*/
	start = 0;
	ret = -ENOMEM;
	schedule_timeout_killable(msecs_to_jiffies(100));
	num_attempts++;
	continue;
	} else {
	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);
	ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, gfp_mask, &info);
	cma_info.nr_migrated += info.nr_migrated;
	cma_info.nr_reclaimed += info.nr_reclaimed;
	cma_info.nr_mapped += info.nr_mapped;
	if (info.err) {
	if (info.err & ACR_ERR_ISOLATE)
	cma_info.nr_isolate_fail++;
	if (info.err & ACR_ERR_MIGRATE)
	cma_info.nr_migrate_fail++;
	if (info.err & ACR_ERR_TEST)
	cma_info.nr_test_fail++;
	}
	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));

	trace_android_vh_cma_alloc_busy_info(&info);
	trace_cma_alloc_busy_retry(cma->name, pfn, pfn_to_page(pfn),
	count, align);

	if (info.failed_pfn && gfp_mask & __GFP_NORETRY) {
	/* try again from following failed page */
	start = (pfn_max_align_up(info.failed_pfn + 1) -
	cma->base_pfn) >> cma->order_per_bit;

	} else {
	/* try again with a bit different memory target */
	start = bitmap_no + mask + 1;
	}
	}

	trace_cma_alloc_finish(cma->name, pfn, page, count, align);
	trace_cma_alloc_info(cma->name, page, count, align, &cma_info);

	/*
	* CMA can allocate multiple page blocks, which results in different
	* blocks being marked with different tags. Reset the tags to ignore
	* those page blocks.
	*/
	if (page) {
	for (i = 0; i < count; i++)
	page_kasan_tag_reset(page + i);
	}

	if (ret && !(gfp_mask & __GFP_NOWARN)) {
	pr_err("%s: %s: alloc failed, req-size: %zu pages, ret: %d\n",
	__func__, cma->name, count, ret);
	cma_debug_show_areas(cma);
	}

	pr_debug("%s(): returned %p\n", __func__, page);
	out:
	trace_android_vh_cma_alloc_finish(cma, page, count, align, gfp_mask, ts);
	if (page) {
	count_vm_event(CMA_ALLOC_SUCCESS);
	cma_sysfs_account_success_pages(cma, count);
	} else if (!(gfp_mask & __GFP_NORETRY)) {
	count_vm_event(CMA_ALLOC_FAIL);
	if (cma)
	cma_sysfs_account_fail_pages(cma, count);
	}

	return page;
	}
	EXPORT_SYMBOL_GPL(cma_alloc);

	/**
	* 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 cma_alloc().
	* It returns false when provided pages do not belong to contiguous area and
	* true otherwise.
	*/
	bool cma_release(struct cma cma, const struct page pages, unsigned int count)
	{
	unsigned long pfn;

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

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

	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);
	trace_cma_release(cma->name, pfn, pages, count);

	return true;
	}
	EXPORT_SYMBOL_GPL(cma_release);

	int cma_for_each_area(int (it)(struct cma cma, void data), void data)
	{
	int i;

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

	if (ret)
	return ret;
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(cma_for_each_area);