| Message ID | 1401757919-30018-2-git-send-email-iamjoonsoo.kim@lge.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Jun 03 2014, Joonsoo Kim wrote: > 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. > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Some small comments below, but in general Acked-by: Michal Nazarewicz <mina86@mina86.com> > > diff --git a/include/linux/cma.h b/include/linux/cma.h > new file mode 100644 > index 0000000..60ba06f > --- /dev/null > +++ b/include/linux/cma.h > @@ -0,0 +1,28 @@ > +/* > + * Contiguous Memory Allocator > + * > + * Copyright LG Electronics Inc., 2014 > + * Written by: > + * 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. > + * Superfluous empty comment line. Also, I'm not certain whether this copyright notice is appropriate here, but that's another story. > + */ > + > +#ifndef __CMA_H__ > +#define __CMA_H__ > + > +struct cma; > + > +extern struct page *cma_alloc(struct cma *cma, unsigned long count, > + unsigned long align); > +extern bool cma_release(struct cma *cma, struct page *pages, > + unsigned long count); > +extern int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > + phys_addr_t limit, phys_addr_t alignment, > + unsigned long bitmap_shift, bool fixed, > + struct cma **res_cma); > +#endif > diff --git a/mm/cma.c b/mm/cma.c > new file mode 100644 > index 0000000..0dae88d > --- /dev/null > +++ b/mm/cma.c > @@ -0,0 +1,329 @@ > +static int __init cma_activate_area(struct cma *cma) > +{ > + int max_bitmapno = cma_bitmap_max_no(cma); > + int bitmap_size = BITS_TO_LONGS(max_bitmapno) * 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__); > + if (!cma->count) > + return 0; Alternatively: + if (!i) + return 0; > + > + 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; > +} Or even: static int __init cma_init_reserved_areas(void) { int i, ret = 0; for (i = 0; !ret && i < cma_area_count; ++i) ret = cma_activate_area(&cma_areas[i]); return ret; } > +int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > + phys_addr_t limit, phys_addr_t alignment, > + unsigned long bitmap_shift, bool fixed, > + struct cma **res_cma) > +{ > + struct cma *cma = &cma_areas[cma_area_count]; Perhaps it would make sense to move this initialisation to the far end of this function? > + 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("Not enough slots for CMA reserved regions!\n"); > + return -ENOSPC; > + } > + > + if (!size) > + 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 >>= PAGE_SHIFT; > + alignment = PAGE_SIZE << max3(MAX_ORDER - 1, pageblock_order, > + (int)alignment); > + base = ALIGN(base, alignment); > + size = ALIGN(size, alignment); > + limit &= ~(alignment - 1); > + /* size should be aligned with bitmap_shift */ > + BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << cma->bitmap_shift)); cma->bitmap_shift is not yet initialised thus the above line should be: BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << bitmap_shift)); > + > + /* 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->bitmap_shift = bitmap_shift; > + *res_cma = cma; > + cma_area_count++; > + > + pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M, > + (unsigned long)base); Doesn't this message end up being: “cma: CMA: reserved …”? pr_fmt adds “cma:” at the beginning, doesn't it? So we should probably drop “CMA:” here. > + > + return 0; > + > +err: > + pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M); > + return ret; > +}
Joonsoo Kim <iamjoonsoo.kim@lge.com> 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. > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> The way patches are split makes it difficult to review. Will it be possible to make changes against one implementation and them move that to generic code. That helps in finding out what exactly changed. > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > index 00e13ce..b3fe1cc 100644 > --- a/drivers/base/Kconfig > +++ b/drivers/base/Kconfig > @@ -283,7 +283,7 @@ config CMA_ALIGNMENT > > If unsure, leave the default value "8". > > -config CMA_AREAS > +config DMA_CMA_AREAS > int "Maximum count of the CMA device-private areas" > default 7 > help for ex: The above can be a seperate patch along with further DMA related cleanups . > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > index 83969f8..48cdac8 100644 > --- a/drivers/base/dma-contiguous.c > +++ b/drivers/base/dma-contiguous.c > @@ -186,7 +186,7 @@ static int __init cma_activate_area(struct cma *cma) > return 0; > } > > -static struct cma cma_areas[MAX_CMA_AREAS]; > +static struct cma cma_areas[MAX_DMA_CMA_AREAS]; > static unsigned cma_area_count; > > static int __init cma_init_reserved_areas(void) > diff --git a/include/linux/cma.h b/include/linux/cma.h > new file mode 100644 > index 0000000..60ba06f > --- /dev/null > +++ b/include/linux/cma.h > @@ -0,0 +1,28 @@ > +/* > + * Contiguous Memory Allocator > + * > + * Copyright LG Electronics Inc., 2014 > + * Written by: > + * 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. > + * > + */ > + > +#ifndef __CMA_H__ > +#define __CMA_H__ > + > +struct cma; > + > +extern struct page *cma_alloc(struct cma *cma, unsigned long count, > + unsigned long align); > +extern bool cma_release(struct cma *cma, struct page *pages, > + unsigned long count); > +extern int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > + phys_addr_t limit, phys_addr_t alignment, > + unsigned long bitmap_shift, bool fixed, > + struct cma **res_cma); > +#endif > diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h > index 772eab5..dfb1dc9 100644 > --- a/include/linux/dma-contiguous.h > +++ b/include/linux/dma-contiguous.h > @@ -63,7 +63,7 @@ struct device; > * There is always at least global CMA area and a few optional device > * private areas configured in kernel .config. > */ > -#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS) > +#define MAX_DMA_CMA_AREAS (1 + CONFIG_DMA_CMA_AREAS) > > extern struct cma *dma_contiguous_default_area; > > @@ -123,7 +123,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, > > #else > > -#define MAX_CMA_AREAS (0) > +#define MAX_DMA_CMA_AREAS (0) > > static inline struct cma *dev_get_cma_area(struct device *dev) > { > diff --git a/mm/Kconfig b/mm/Kconfig > index 7511b4a..0877ddc 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -515,6 +515,17 @@ 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". > + If we have 7 declare continugous request, a kvm cma allocation request will fail ? > 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..0dae88d > --- /dev/null > +++ b/mm/cma.c > @@ -0,0 +1,329 @@ > +/* > + * 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> > + > +struct cma { > + unsigned long base_pfn; > + unsigned long count; > + unsigned long *bitmap; > + unsigned long bitmap_shift; I guess this is added to accommodate the kvm specific alloc chunks. May be you should do this as a patch against kvm implementation and then move the code to generic ? > + struct mutex lock; > +}; > + -aneesh
On Tue, Jun 03, 2014 at 08:56:00AM +0200, Michal Nazarewicz wrote: > On Tue, Jun 03 2014, Joonsoo Kim wrote: > > 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. > > > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > Some small comments below, but in general > > Acked-by: Michal Nazarewicz <mina86@mina86.com> Hello, Michal. Thanks! > > > > > diff --git a/include/linux/cma.h b/include/linux/cma.h > > new file mode 100644 > > index 0000000..60ba06f > > --- /dev/null > > +++ b/include/linux/cma.h > > @@ -0,0 +1,28 @@ > > +/* > > + * Contiguous Memory Allocator > > + * > > + * Copyright LG Electronics Inc., 2014 > > + * Written by: > > + * 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. > > + * > > Superfluous empty comment line. > > Also, I'm not certain whether this copyright notice is appropriate here, > but that's another story. Yeah, I will remove copyright notice in .h file. > > > + */ > > + > > +#ifndef __CMA_H__ > > +#define __CMA_H__ > > + > > +struct cma; > > + > > +extern struct page *cma_alloc(struct cma *cma, unsigned long count, > > + unsigned long align); > > +extern bool cma_release(struct cma *cma, struct page *pages, > > + unsigned long count); > > +extern int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > > + phys_addr_t limit, phys_addr_t alignment, > > + unsigned long bitmap_shift, bool fixed, > > + struct cma **res_cma); > > +#endif > > > diff --git a/mm/cma.c b/mm/cma.c > > new file mode 100644 > > index 0000000..0dae88d > > --- /dev/null > > +++ b/mm/cma.c > > @@ -0,0 +1,329 @@ > > > +static int __init cma_activate_area(struct cma *cma) > > +{ > > + int max_bitmapno = cma_bitmap_max_no(cma); > > + int bitmap_size = BITS_TO_LONGS(max_bitmapno) * 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__); > > + if (!cma->count) > > + return 0; > > Alternatively: > > + if (!i) > + return 0; I prefer cma->count than i, since it represents what it does itself. > > + > > + 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; > > +} > > Or even: > > static int __init cma_init_reserved_areas(void) > { > int i, ret = 0; > for (i = 0; !ret && i < cma_area_count; ++i) > ret = cma_activate_area(&cma_areas[i]); > return ret; > } I think that originial implementation is better, since it seems more readable to me. > > +int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > > + phys_addr_t limit, phys_addr_t alignment, > > + unsigned long bitmap_shift, bool fixed, > > + struct cma **res_cma) > > +{ > > + struct cma *cma = &cma_areas[cma_area_count]; > > Perhaps it would make sense to move this initialisation to the far end > of this function? Yes, I will move it down. > > + 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("Not enough slots for CMA reserved regions!\n"); > > + return -ENOSPC; > > + } > > + > > + if (!size) > > + 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 >>= PAGE_SHIFT; > > + alignment = PAGE_SIZE << max3(MAX_ORDER - 1, pageblock_order, > > + (int)alignment); > > + base = ALIGN(base, alignment); > > + size = ALIGN(size, alignment); > > + limit &= ~(alignment - 1); > > + /* size should be aligned with bitmap_shift */ > > + BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << cma->bitmap_shift)); > > cma->bitmap_shift is not yet initialised thus the above line should be: > > BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << bitmap_shift)); Yes, I will fix it. > > + > > + /* 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->bitmap_shift = bitmap_shift; > > + *res_cma = cma; > > + cma_area_count++; > > + > > + pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M, > > + (unsigned long)base); > > Doesn't this message end up being: “cma: CMA: reserved …”? pr_fmt adds > “cma:” at the beginning, doesn't it? So we should probably drop “CMA:” > here. Okay. Will do. Thanks.
On Thu, Jun 05, 2014 at 11:09:05PM +0530, Aneesh Kumar K.V wrote: > Joonsoo Kim <iamjoonsoo.kim@lge.com> 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. > > > > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > > The way patches are split makes it difficult to review. Will it be > possible to make changes against one implementation and them move that > to generic code. That helps in finding out what exactly changed. > Hello, You are right! I will respin this patchset as the form you recommended. > > > > diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig > > index 00e13ce..b3fe1cc 100644 > > --- a/drivers/base/Kconfig > > +++ b/drivers/base/Kconfig > > @@ -283,7 +283,7 @@ config CMA_ALIGNMENT > > > > If unsure, leave the default value "8". > > > > -config CMA_AREAS > > +config DMA_CMA_AREAS > > int "Maximum count of the CMA device-private areas" > > default 7 > > help > > for ex: The above can be a seperate patch along with further DMA related > cleanups . Okay. > > > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > > index 83969f8..48cdac8 100644 > > --- a/drivers/base/dma-contiguous.c > > +++ b/drivers/base/dma-contiguous.c > > @@ -186,7 +186,7 @@ static int __init cma_activate_area(struct cma *cma) > > return 0; > > } > > > > -static struct cma cma_areas[MAX_CMA_AREAS]; > > +static struct cma cma_areas[MAX_DMA_CMA_AREAS]; > > static unsigned cma_area_count; > > > > static int __init cma_init_reserved_areas(void) > > diff --git a/include/linux/cma.h b/include/linux/cma.h > > new file mode 100644 > > index 0000000..60ba06f > > --- /dev/null > > +++ b/include/linux/cma.h > > @@ -0,0 +1,28 @@ > > +/* > > + * Contiguous Memory Allocator > > + * > > + * Copyright LG Electronics Inc., 2014 > > + * Written by: > > + * 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. > > + * > > + */ > > + > > +#ifndef __CMA_H__ > > +#define __CMA_H__ > > + > > +struct cma; > > + > > +extern struct page *cma_alloc(struct cma *cma, unsigned long count, > > + unsigned long align); > > +extern bool cma_release(struct cma *cma, struct page *pages, > > + unsigned long count); > > +extern int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, > > + phys_addr_t limit, phys_addr_t alignment, > > + unsigned long bitmap_shift, bool fixed, > > + struct cma **res_cma); > > +#endif > > diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h > > index 772eab5..dfb1dc9 100644 > > --- a/include/linux/dma-contiguous.h > > +++ b/include/linux/dma-contiguous.h > > @@ -63,7 +63,7 @@ struct device; > > * There is always at least global CMA area and a few optional device > > * private areas configured in kernel .config. > > */ > > -#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS) > > +#define MAX_DMA_CMA_AREAS (1 + CONFIG_DMA_CMA_AREAS) > > > > extern struct cma *dma_contiguous_default_area; > > > > @@ -123,7 +123,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, > > > > #else > > > > -#define MAX_CMA_AREAS (0) > > +#define MAX_DMA_CMA_AREAS (0) > > > > static inline struct cma *dev_get_cma_area(struct device *dev) > > { > > diff --git a/mm/Kconfig b/mm/Kconfig > > index 7511b4a..0877ddc 100644 > > --- a/mm/Kconfig > > +++ b/mm/Kconfig > > @@ -515,6 +515,17 @@ 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". > > + > > If we have 7 declare continugous request, a kvm cma allocation request will fail ? Yes. If you need more, you can increase it. :) > > 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..0dae88d > > --- /dev/null > > +++ b/mm/cma.c > > @@ -0,0 +1,329 @@ > > +/* > > + * 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> > > + > > +struct cma { > > + unsigned long base_pfn; > > + unsigned long count; > > + unsigned long *bitmap; > > + unsigned long bitmap_shift; > > I guess this is added to accommodate the kvm specific alloc chunks. May > be you should do this as a patch against kvm implementation and then > move the code to generic ? Yes, this is for kvm specific alloc chunks. I will consider which one is better for the base implementation and makes patches against it. Thanks.
diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 00e13ce..b3fe1cc 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -283,7 +283,7 @@ config CMA_ALIGNMENT If unsure, leave the default value "8". -config CMA_AREAS +config DMA_CMA_AREAS int "Maximum count of the CMA device-private areas" default 7 help diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c index 83969f8..48cdac8 100644 --- a/drivers/base/dma-contiguous.c +++ b/drivers/base/dma-contiguous.c @@ -186,7 +186,7 @@ static int __init cma_activate_area(struct cma *cma) return 0; } -static struct cma cma_areas[MAX_CMA_AREAS]; +static struct cma cma_areas[MAX_DMA_CMA_AREAS]; static unsigned cma_area_count; static int __init cma_init_reserved_areas(void) diff --git a/include/linux/cma.h b/include/linux/cma.h new file mode 100644 index 0000000..60ba06f --- /dev/null +++ b/include/linux/cma.h @@ -0,0 +1,28 @@ +/* + * Contiguous Memory Allocator + * + * Copyright LG Electronics Inc., 2014 + * Written by: + * 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. + * + */ + +#ifndef __CMA_H__ +#define __CMA_H__ + +struct cma; + +extern struct page *cma_alloc(struct cma *cma, unsigned long count, + unsigned long align); +extern bool cma_release(struct cma *cma, struct page *pages, + unsigned long count); +extern int __init cma_declare_contiguous(phys_addr_t size, phys_addr_t base, + phys_addr_t limit, phys_addr_t alignment, + unsigned long bitmap_shift, bool fixed, + struct cma **res_cma); +#endif diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h index 772eab5..dfb1dc9 100644 --- a/include/linux/dma-contiguous.h +++ b/include/linux/dma-contiguous.h @@ -63,7 +63,7 @@ struct device; * There is always at least global CMA area and a few optional device * private areas configured in kernel .config. */ -#define MAX_CMA_AREAS (1 + CONFIG_CMA_AREAS) +#define MAX_DMA_CMA_AREAS (1 + CONFIG_DMA_CMA_AREAS) extern struct cma *dma_contiguous_default_area; @@ -123,7 +123,7 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, #else -#define MAX_CMA_AREAS (0) +#define MAX_DMA_CMA_AREAS (0) static inline struct cma *dev_get_cma_area(struct device *dev) { diff --git a/mm/Kconfig b/mm/Kconfig index 7511b4a..0877ddc 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -515,6 +515,17 @@ 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..0dae88d --- /dev/null +++ b/mm/cma.c @@ -0,0 +1,329 @@ +/* + * 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> + +struct cma { + unsigned long base_pfn; + unsigned long count; + unsigned long *bitmap; + unsigned long bitmap_shift; + 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_mask(struct cma *cma, + unsigned long align_order) +{ + return (1 << (align_order >> cma->bitmap_shift)) - 1; +} + +static unsigned long cma_bitmap_max_no(struct cma *cma) +{ + return cma->count >> cma->bitmap_shift; +} + +static unsigned long cma_bitmap_pages_to_bits(struct cma *cma, + unsigned long pages) +{ + return ALIGN(pages, 1 << cma->bitmap_shift) >> cma->bitmap_shift; +} + +static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count) +{ + unsigned long bitmapno, nr_bits; + + bitmapno = (pfn - cma->base_pfn) >> cma->bitmap_shift; + 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 max_bitmapno = cma_bitmap_max_no(cma); + int bitmap_size = BITS_TO_LONGS(max_bitmapno) * 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__); + if (!cma->count) + return 0; + + 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). + * @bitmap_shift: 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 size, phys_addr_t base, + phys_addr_t limit, phys_addr_t alignment, + unsigned long bitmap_shift, bool fixed, + struct cma **res_cma) +{ + 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("Not enough slots for CMA reserved regions!\n"); + return -ENOSPC; + } + + if (!size) + 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 >>= PAGE_SHIFT; + alignment = PAGE_SIZE << max3(MAX_ORDER - 1, pageblock_order, + (int)alignment); + base = ALIGN(base, alignment); + size = ALIGN(size, alignment); + limit &= ~(alignment - 1); + /* size should be aligned with bitmap_shift */ + BUG_ON(!IS_ALIGNED(size >> PAGE_SHIFT, 1 << cma->bitmap_shift)); + + /* 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->bitmap_shift = bitmap_shift; + *res_cma = cma; + cma_area_count++; + + pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M, + (unsigned long)base); + + return 0; + +err: + pr_err("CMA: 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, unsigned long count, + unsigned long align) +{ + unsigned long mask, pfn, start = 0; + unsigned long max_bitmapno, bitmapno, nr_bits; + struct page *page = NULL; + int ret; + + if (!cma || !cma->count) + return NULL; + + pr_debug("%s(cma %p, count %ld, align %ld)\n", __func__, (void *)cma, + count, align); + + if (!count) + return NULL; + + mask = cma_bitmap_mask(cma, align); + max_bitmapno = cma_bitmap_max_no(cma); + nr_bits = cma_bitmap_pages_to_bits(cma, count); + + for (;;) { + mutex_lock(&cma->lock); + bitmapno = bitmap_find_next_zero_area(cma->bitmap, + max_bitmapno, start, nr_bits, mask); + if (bitmapno >= max_bitmapno) { + 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->bitmap_shift); + 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; + } + clear_cma_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 = 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, unsigned long 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; +}
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. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>