Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> writes: > Currently, there are two users on CMA functionality, one is the DMA > subsystem and the other is the kvm on powerpc. They have their own code > to manage CMA reserved area even if they looks really similar. > From my guess, it is caused by some needs on bitmap management. Kvm side > wants to maintain bitmap not for 1 page, but for more size. Eventually it > use bitmap where one bit represents 64 pages. > > When I implement CMA related patches, I should change those two places > to apply my change and it seem to be painful to me. I want to change > this situation and reduce future code management overhead through > this patch. > > This change could also help developer who want to use CMA in their > new feature development, since they can use CMA easily without > copying & pasting this reserved area management code. > > In previous patches, we have prepared some features to generalize > CMA reserved area management and now it's time to do it. This patch > moves core functions to mm/cma.c and change DMA APIs to use > these functions. > > There is no functional change in DMA APIs. > > v2: There is no big change from v1 in mm/cma.c. Mostly renaming. > > Acked-by: Michal Nazarewicz <mina86@xxxxxxxxxx> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index 00e13ce..4eac559 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -283,16 +283,6 @@ config CMA_ALIGNMENT > > If unsure, leave the default value "8". > > -config CMA_AREAS > - int "Maximum count of the CMA device-private areas" > - default 7 > - help > - CMA allows to create CMA areas for particular devices. This parameter > - sets the maximum number of such device private CMA areas in the > - system. > - > - If unsure, leave the default value "7". > - > endif > > endmenu > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > index 9bc9340..f177f73 100644 > --- a/drivers/base/dma-contiguous.c > +++ b/drivers/base/dma-contiguous.c > @@ -24,25 +24,10 @@ > > #include <linux/memblock.h> > #include <linux/err.h> > -#include <linux/mm.h> > -#include <linux/mutex.h> > -#include <linux/page-isolation.h> > #include <linux/sizes.h> > -#include <linux/slab.h> > -#include <linux/swap.h> > -#include <linux/mm_types.h> > #include <linux/dma-contiguous.h> > #include <linux/log2.h> > - > -struct cma { > - unsigned long base_pfn; > - unsigned long count; > - unsigned long *bitmap; > - int order_per_bit; /* Order of pages represented by one bit */ > - struct mutex lock; > -}; > - > -struct cma *dma_contiguous_default_area; > +#include <linux/cma.h> > > #ifdef CONFIG_CMA_SIZE_MBYTES > #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES > @@ -50,6 +35,8 @@ struct cma *dma_contiguous_default_area; > #define CMA_SIZE_MBYTES 0 > #endif > > +struct cma *dma_contiguous_default_area; > + > /* > * Default global CMA area size can be defined in kernel's .config. > * This is useful mainly for distro maintainers to create a kernel > @@ -156,199 +143,13 @@ void __init dma_contiguous_reserve(phys_addr_t limit) > } > } > > -static DEFINE_MUTEX(cma_mutex); > - > -static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) > -{ > - return (1 << (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, 1 << cma->order_per_bit) >> cma->order_per_bit; > -} > - > -static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) > -{ > - unsigned long bitmapno, nr_bits; > - > - bitmapno = (pfn - cma->base_pfn) >> cma->order_per_bit; > - nr_bits = cma_bitmap_pages_to_bits(cma, count); > - > - mutex_lock(&cma->lock); > - bitmap_clear(cma->bitmap, bitmapno, nr_bits); > - mutex_unlock(&cma->lock); > -} > - > -static int __init cma_activate_area(struct cma *cma) > -{ > - int bitmap_maxno = cma_bitmap_maxno(cma); > - int bitmap_size = BITS_TO_LONGS(bitmap_maxno) * sizeof(long); > - unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; > - unsigned i = cma->count >> pageblock_order; > - struct zone *zone; > - > - pr_debug("%s()\n", __func__); > - > - 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); > - return -EINVAL; > -} > - > -static struct cma cma_areas[MAX_CMA_AREAS]; > -static unsigned cma_area_count; > - > -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); > - > -/** > - * dma_contiguous_reserve_area() - reserve custom contiguous area > - * @size: Size of the reserved area (in bytes), > - * @base: Base address of the reserved area optional, use 0 for any > - * @limit: End address of the reserved memory (optional, 0 for any). > - * @alignment: Alignment for the contiguous memory area, should be power of 2 > - * @order_per_bit: Order of pages represented by one bit on bitmap. > - * @res_cma: Pointer to store the created cma region. > - * @fixed: hint about where to place the reserved area > - * > - * 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 for specific > - * devices. > - * > - * If @fixed is true, reserve contiguous area at exactly @base. If false, > - * reserve in range from @base to @limit. > - */ > -static int __init __dma_contiguous_reserve_area(phys_addr_t size, > - phys_addr_t base, phys_addr_t limit, > - phys_addr_t alignment, int order_per_bit, > - struct cma **res_cma, bool fixed) > -{ > - struct cma *cma = &cma_areas[cma_area_count]; > - int ret = 0; > - > - pr_debug("%s(size %lx, base %08lx, limit %08lx align_order %08lx)\n", > - __func__, (unsigned long)size, (unsigned long)base, > - (unsigned long)limit, (unsigned long)alignment); > - > - /* Sanity checks */ > - if (cma_area_count == ARRAY_SIZE(cma_areas)) { > - pr_err("%s(): Not enough slots for CMA reserved regions!\n", > - __func__); > - return -ENOSPC; > - } > - > - if (!size) > - return -EINVAL; > - > - if (alignment && !is_power_of_2(alignment)) > - return -EINVAL; > - > - /* > - * Sanitise input arguments. > - * CMA area should be at least MAX_ORDER - 1 aligned. Otherwise, > - * CMA area could be merged into other MIGRATE_TYPE by buddy mechanism > - * and CMA property will be broken. > - */ > - 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 */ > - BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)); > - > - /* 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; > - } > - } > - > - /* > - * Each reserved area must be initialised later, when more kernel > - * subsystems (like slab allocator) are available. > - */ > - cma->base_pfn = PFN_DOWN(base); > - cma->count = size >> PAGE_SHIFT; > - cma->order_per_bit = order_per_bit; > - *res_cma = cma; > - cma_area_count++; > - > - pr_info("%s(): reserved %ld MiB at %08lx\n", > - __func__, (unsigned long)size / SZ_1M, (unsigned long)base); > - return 0; > - > -err: > - pr_err("%s(): failed to reserve %ld MiB\n", > - __func__, (unsigned long)size / SZ_1M); > - return ret; > -} > - > int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, > phys_addr_t limit, struct cma **res_cma, > bool fixed) > { > int ret; > > - ret = __dma_contiguous_reserve_area(size, base, limit, 0, 0, > - res_cma, fixed); > + ret = cma_declare_contiguous(size, base, limit, 0, 0, res_cma, fixed); > if (ret) > return ret; > > @@ -358,124 +159,17 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, > return 0; > } > > -/** > - * 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 dev_get_cma_area() helper > - * function. > - */ > -static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, > - unsigned int align) > -{ > - unsigned long mask, pfn, start = 0; > - unsigned long bitmap_maxno, bitmapno, nr_bits; > - 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); > - nr_bits = cma_bitmap_pages_to_bits(cma, count); > - > - for (;;) { > - mutex_lock(&cma->lock); > - bitmapno = bitmap_find_next_zero_area(cma->bitmap, > - bitmap_maxno, start, nr_bits, mask); > - if (bitmapno >= bitmap_maxno) { > - mutex_unlock(&cma->lock); > - break; > - } > - bitmap_set(cma->bitmap, bitmapno, nr_bits); > - /* > - * 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 + (bitmapno << 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; > - } else if (ret != -EBUSY) { > - clear_cma_bitmap(cma, pfn, count); > - break; > - } > - clear_cma_bitmap(cma, pfn, count); > - 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 = bitmapno + mask + 1; > - } > - > - pr_debug("%s(): returned %p\n", __func__, page); > - return page; > -} > - > struct page *dma_alloc_from_contiguous(struct device *dev, int count, > unsigned int align) > { > - struct cma *cma = dev_get_cma_area(dev); > - > if (align > CONFIG_CMA_ALIGNMENT) > align = CONFIG_CMA_ALIGNMENT; > > - return __dma_alloc_from_contiguous(cma, count, align); > -} > - > -/** > - * 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. > - */ > -static bool __dma_release_from_contiguous(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); > - clear_cma_bitmap(cma, pfn, count); > - > - return true; > + return cma_alloc(dev_get_cma_area(dev), count, align); > } > > bool dma_release_from_contiguous(struct device *dev, struct page *pages, > int count) > { > - struct cma *cma = dev_get_cma_area(dev); > - > - return __dma_release_from_contiguous(cma, pages, count); > + return cma_release(dev_get_cma_area(dev), pages, count); > } > diff --git a/include/linux/cma.h b/include/linux/cma.h > new file mode 100644 > index 0000000..e38efe9 > --- /dev/null > +++ b/include/linux/cma.h > @@ -0,0 +1,12 @@ > +#ifndef __CMA_H__ > +#define __CMA_H__ > + > +struct cma; > + > +extern int __init cma_declare_contiguous(phys_addr_t size, > + phys_addr_t base, phys_addr_t limit, > + phys_addr_t alignment, int order_per_bit, > + struct cma **res_cma, bool fixed); > +extern struct page *cma_alloc(struct cma *cma, int count, unsigned int align); > +extern bool cma_release(struct cma *cma, struct page *pages, int count); > +#endif > diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h > index 772eab5..a40c1f3 100644 > --- a/include/linux/dma-contiguous.h > +++ b/include/linux/dma-contiguous.h > @@ -53,9 +53,10 @@ > > #ifdef __KERNEL__ > > +#include <linux/device.h> > + > struct cma; > struct page; > -struct device; > > #ifdef CONFIG_DMA_CMA > > diff --git a/mm/Kconfig b/mm/Kconfig > index 3e9977a..f4899ec 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -508,6 +508,17 @@ config CMA_DEBUG > processing calls such as dma_alloc_from_contiguous(). > This option does not affect warning and error messages. > > +config CMA_AREAS > + int "Maximum count of the CMA areas" > + depends on CMA > + default 7 > + help > + CMA allows to create CMA areas for particular purpose, mainly, > + used as device private area. This parameter sets the maximum > + number of CMA area in the system. > + > + If unsure, leave the default value "7". > + > config ZBUD > tristate > default n > diff --git a/mm/Makefile b/mm/Makefile > index 1eaa70b..bc0422b 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -62,3 +62,4 @@ obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o > obj-$(CONFIG_ZBUD) += zbud.o > obj-$(CONFIG_ZSMALLOC) += zsmalloc.o > obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o > +obj-$(CONFIG_CMA) += cma.o > diff --git a/mm/cma.c b/mm/cma.c > new file mode 100644 > index 0000000..1e1b017 > --- /dev/null > +++ b/mm/cma.c > @@ -0,0 +1,330 @@ > +/* > + * 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@xxxxxxxxxxx> > + * Michal Nazarewicz <mina86@xxxxxxxxxx> > + * Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> > + * Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > + * > + * 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> > + > +struct cma { > + unsigned long base_pfn; > + unsigned long count; > + unsigned long *bitmap; > + int order_per_bit; /* Order of pages represented by one bit */ > + struct mutex lock; > +}; > + > +/* > + * There is always at least global CMA area and a few optional > + * areas configured in kernel .config. > + */ > +#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS) > + > +static struct cma cma_areas[MAX_CMA_AREAS]; > +static unsigned cma_area_count; > +static DEFINE_MUTEX(cma_mutex); > + > +static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) > +{ > + return (1 << (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, 1 << cma->order_per_bit) >> cma->order_per_bit; > +} > + > +static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) > +{ > + unsigned long bitmapno, nr_bits; > + > + bitmapno = (pfn - cma->base_pfn) >> cma->order_per_bit; > + nr_bits = cma_bitmap_pages_to_bits(cma, count); > + > + mutex_lock(&cma->lock); > + bitmap_clear(cma->bitmap, bitmapno, nr_bits); > + mutex_unlock(&cma->lock); > +} > + > +static int __init cma_activate_area(struct cma *cma) > +{ > + int bitmap_maxno = cma_bitmap_maxno(cma); > + int bitmap_size = BITS_TO_LONGS(bitmap_maxno) * sizeof(long); > + unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; > + unsigned i = cma->count >> pageblock_order; > + struct zone *zone; > + > + pr_debug("%s()\n", __func__); > + > + 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); > + 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_declare_contiguous() - reserve custom contiguous area > + * @size: Size of the reserved area (in bytes), > + * @base: Base address of the reserved area optional, use 0 for any > + * @limit: End address of the reserved memory (optional, 0 for any). > + * @alignment: Alignment for the contiguous memory area, should be power of 2 > + * @order_per_bit: Order of pages represented by one bit on bitmap. > + * @res_cma: Pointer to store the created cma region. > + * @fixed: hint about where to place the reserved area > + * > + * 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 size, > + phys_addr_t base, phys_addr_t limit, > + phys_addr_t alignment, int order_per_bit, > + struct cma **res_cma, bool fixed) > +{ > + struct cma *cma = &cma_areas[cma_area_count]; > + 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); > + > + /* Sanity checks */ > + if (cma_area_count == ARRAY_SIZE(cma_areas)) { > + pr_err("%s(): Not enough slots for CMA reserved regions!\n", > + __func__); > + return -ENOSPC; > + } > + > + if (!size) > + return -EINVAL; > + > + if (alignment && !is_power_of_2(alignment)) > + return -EINVAL; > + > + /* > + * Sanitise input arguments. > + * CMA area should be at least MAX_ORDER - 1 aligned. Otherwise, > + * CMA area could be merged into other MIGRATE_TYPE by buddy mechanism > + * and CMA property will be broken. > + */ > + 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 */ > + BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)); > + > + /* 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; > + } > + } > + > + /* > + * Each reserved area must be initialised later, when more kernel > + * subsystems (like slab allocator) are available. > + */ > + cma->base_pfn = PFN_DOWN(base); > + cma->count = size >> PAGE_SHIFT; > + cma->order_per_bit = order_per_bit; > + *res_cma = cma; > + cma_area_count++; > + > + pr_info("%s(): reserved %ld MiB at %08lx\n", > + __func__, (unsigned long)size / SZ_1M, (unsigned long)base); > + return 0; > + > +err: > + pr_err("%s(): failed to reserve %ld MiB\n", > + __func__, (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, bitmapno, nr_bits; > + 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); > + nr_bits = cma_bitmap_pages_to_bits(cma, count); > + > + for (;;) { > + mutex_lock(&cma->lock); > + bitmapno = bitmap_find_next_zero_area(cma->bitmap, > + bitmap_maxno, start, nr_bits, mask); > + if (bitmapno >= bitmap_maxno) { > + mutex_unlock(&cma->lock); > + break; > + } > + bitmap_set(cma->bitmap, bitmapno, nr_bits); > + /* > + * 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 + (bitmapno << 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; > + } else if (ret != -EBUSY) { > + clear_cma_bitmap(cma, pfn, count); > + break; > + } > + clear_cma_bitmap(cma, pfn, count); > + 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 = bitmapno + 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); > + clear_cma_bitmap(cma, pfn, count); > + > + return true; > +} > -- > 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html