Linaro-mm-sig December 2011

linaro-mm-sig@lists.linaro.org

25 participants
13 discussions

[PATCH 00/14] DMA-mapping framework redesign preparation

by Marek Szyprowski

Hello eveyone, On Linaro Memory Management meeting in Budapest (May 2011) we have discussed about the design of DMA mapping framework. We tried to identify the drawbacks and limitations as well as to provide some a solution for them. The discussion was mainly about ARM architecture, but some of the conclusions need to be applied to cross-architecture code. The first issue we identified is the fact that on some platform (again, mainly ARM) there are several functions for allocating DMA buffers: dma_alloc_coherent, dma_alloc_writecombine and dma_alloc_noncoherent (not functional now). For each of them there is a match dma_free_* function. This gives us quite a lot of functions in the public API and complicates things when we need to have several different implementations for different devices selected in runtime (if IOMMU controller is available only for a few devices in the system). Also the drivers which use less common variants are less portable because of the lacks of dma_alloc_writecombine on other architectures. The solution we found is to introduce a new public dma mapping functions with additional attributes argument: dma_alloc_attrs and dma_free_attrs(). This way all different kinds of architecture specific buffer mappings can be hidden behind the attributes without the need of creating several versions of dma_alloc_ function. dma_alloc_coherent() can be wrapped on top of new dma_alloc_attrs() with NULL attrs parameter. dma_alloc_writecombine and dma_alloc_noncoherent can be implemented as a simple wrappers which sets attributes to DMA_ATTRS_WRITECOMBINE or DMA_ATTRS_NON_CONSISTENT respectively. These new attributes will be implemented only on the architectures that really support them, the others will simply ignore them defaulting to the dma_alloc_coherent equivalent. The next step in dma mapping framework update is the introduction of dma_mmap/dma_mmap_attrs() function. There are a number of drivers (mainly V4L2 and ALSA) that only exports the DMA buffers to user space. Creating a userspace mapping with correct page attributes is not an easy task for the driver. Also the DMA-mapping framework is the only place where the complete information about the allocated pages is available, especially if the implementation uses IOMMU controller to provide a contiguous buffer in DMA address space which is scattered in physical memory space. Usually these drivers don't touch the buffer data at all, so the mapping in kernel virtual address space is not needed. We can introduce DMA_ATTRIB_NO_KERNEL_MAPPING attribute which lets kernel to skip/ignore creation of kernel virtual mapping. This way we can save previous vmalloc area and simply some mapping operation on a few architectures. This patch series is a preparation for the above changes in the public dma mapping API. The main goal is to modify dma_map_ops structure and let all users to use for implementation of the new public funtions. The proof-of-concept patches for ARM architecture have been already posted a few times and now they are working resonably well. They perform conversion to dma_map_ops based implementation and add support for generic IOMMU-based dma mapping implementation. To get them merged we first need to get acceptance for the changes in the common, cross-architecture structures. More information about these patches can be found in the following threads: http://www.spinics.net/lists/linux-mm/msg19856.html http://www.spinics.net/lists/linux-mm/msg21241.html http://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000571.html http://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000577.html http://www.spinics.net/lists/linux-mm/msg25490.html The patches are prepared on top of Linux Kernel v3.2-rc6. I would appreciate any comments and help with getting this patch series into linux-next tree. The idea apllied in this patch set have been also presented during the Kernel Summit 2011 and ELC-E 2011 in Prague, in the presentation 'ARM DMA-Mapping Framework Redesign and IOMMU integration'. I'm really sorry if I missed any of the relevant architecture mailing lists. I've did my best to include everyone. Feel free to forward this patchset to all interested developers and maintainers. I've already feel like a nasty spammer. Best regards Marek Szyprowski Samsung Poland R&D Center Patch summary: Andrzej Pietrasiewicz (9): X86: adapt for dma_map_ops changes MIPS: adapt for dma_map_ops changes PowerPC: adapt for dma_map_ops changes IA64: adapt for dma_map_ops changes SPARC: adapt for dma_map_ops changes Alpha: adapt for dma_map_ops changes SH: adapt for dma_map_ops changes Microblaze: adapt for dma_map_ops changes Unicore32: adapt for dma_map_ops changes Marek Szyprowski (5): common: dma-mapping: introduce alloc_attrs and free_attrs methods common: dma-mapping: remove old alloc_coherent and free_coherent methods common: dma-mapping: introduce mmap method common: DMA-mapping: add WRITE_COMBINE attribute common: DMA-mapping: add NON-CONSISTENT attribute Documentation/DMA-attributes.txt | 19 +++++++++++++++++++ arch/alpha/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/alpha/kernel/pci-noop.c | 10 ++++++---- arch/alpha/kernel/pci_iommu.c | 10 ++++++---- arch/ia64/hp/common/sba_iommu.c | 11 ++++++----- arch/ia64/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/ia64/kernel/pci-swiotlb.c | 9 +++++---- arch/ia64/sn/pci/pci_dma.c | 9 +++++---- arch/microblaze/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/microblaze/kernel/dma.c | 10 ++++++---- arch/mips/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/mips/mm/dma-default.c | 8 ++++---- arch/powerpc/include/asm/dma-mapping.h | 24 ++++++++++++++++-------- arch/powerpc/kernel/dma-iommu.c | 10 ++++++---- arch/powerpc/kernel/dma-swiotlb.c | 4 ++-- arch/powerpc/kernel/dma.c | 10 ++++++---- arch/powerpc/kernel/ibmebus.c | 10 ++++++---- arch/powerpc/platforms/cell/iommu.c | 16 +++++++++------- arch/powerpc/platforms/ps3/system-bus.c | 13 +++++++------ arch/sh/include/asm/dma-mapping.h | 28 ++++++++++++++++++---------- arch/sh/kernel/dma-nommu.c | 4 ++-- arch/sh/mm/consistent.c | 6 ++++-- arch/sparc/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/sparc/kernel/iommu.c | 10 ++++++---- arch/sparc/kernel/ioport.c | 18 ++++++++++-------- arch/sparc/kernel/pci_sun4v.c | 9 +++++---- arch/unicore32/include/asm/dma-mapping.h | 18 ++++++++++++------ arch/unicore32/mm/dma-swiotlb.c | 4 ++-- arch/x86/include/asm/dma-mapping.h | 26 ++++++++++++++++---------- arch/x86/kernel/amd_gart_64.c | 11 ++++++----- arch/x86/kernel/pci-calgary_64.c | 9 +++++---- arch/x86/kernel/pci-dma.c | 3 ++- arch/x86/kernel/pci-nommu.c | 6 +++--- arch/x86/kernel/pci-swiotlb.c | 12 +++++++----- arch/x86/xen/pci-swiotlb-xen.c | 4 ++-- drivers/iommu/amd_iommu.c | 10 ++++++---- drivers/iommu/intel-iommu.c | 9 +++++---- drivers/xen/swiotlb-xen.c | 5 +++-- include/linux/dma-attrs.h | 2 ++ include/linux/dma-mapping.h | 13 +++++++++---- include/linux/swiotlb.h | 6 ++++-- include/xen/swiotlb-xen.h | 6 ++++-- lib/swiotlb.c | 5 +++-- 43 files changed, 305 insertions(+), 182 deletions(-) -- 1.7.1.569.g6f426

12 years, 8 months

[PATCH 0/3] Introduce DMA buffer sharing mechanism

by Sumit Semwal

Hello Everyone, Post some discussion as an RFC, here is the patch for introducing DMA buffer sharing mechanism - change history is in the changelog below. Various subsystems - V4L2, GPU-accessors, DRI to name a few - have felt the need to have a common mechanism to share memory buffers across different devices - ARM, video hardware, GPU. This need comes forth from a variety of use cases including cameras, image processing, video recorders, sound processing, DMA engines, GPU and display buffers, amongst others. This patch attempts to define such a buffer sharing mechanism - it is the result of discussions from a couple of memory-management mini-summits held by Linaro to understand and address common needs around memory management. [1] A new dma_buf buffer object is added, with operations and API to allow easy sharing of this buffer object across devices. The framework allows: - a new buffer object to be created with fixed size, associated with a file pointer and allocator-defined operations for this buffer object. This operation is called the 'export' operation. - different devices to 'attach' themselves to this buffer object, to facilitate backing storage negotiation, using dma_buf_attach() API. - this exported buffer object to be shared with the other entity by asking for its 'file-descriptor (fd)', and sharing the fd across. - a received fd to get the buffer object back, where it can be accessed using the associated exporter-defined operations. - the exporter and user to share the buffer object's scatterlist using map_dma_buf and unmap_dma_buf operations. Documentation present in the patch-set gives more details. For 1st version, dma-buf is marked as an EXPERIMENTAL driver, which we can remove for later versions with additional usage and testing. *IMPORTANT*: [see https://lkml.org/lkml/2011/12/20/211 for more details] For this first version, A buffer shared using the dma_buf sharing API: - *may* be exported to user space using "mmap" *ONLY* by exporter, outside of this framework. - may be used *ONLY* by importers that do not need CPU access to the buffer. This is based on design suggestions from many people at the mini-summits, most notably from Arnd Bergmann <arnd(a)arndb.de>, Rob Clark <rob(a)ti.com> and Daniel Vetter <daniel(a)ffwll.ch>. The implementation is inspired from proof-of-concept patch-set from Tomasz Stanislawski <t.stanislaws(a)samsung.com>, who demonstrated buffer sharing between two v4l2 devices. [2] Some sample implementations and WIP for dma-buf users and exporters are available at [3] and [4]. [These are not being submitted for discussion / inclusion right now, but are for reference only] References: [1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement [2]: http://lwn.net/Articles/454389 [3]: Dave Airlie's prime support: http://cgit.freedesktop.org/~airlied/linux/log/?h=drm-prime-dmabuf [4]: Rob Clark's sharing between DRM and V4L2: https://github.com/robclark/kernel-omap4/commits/drmplane-dmabuf Patchset based on top of 3.2-rc7, the current version can be found at http://git.linaro.org/gitweb?p=people/sumitsemwal/linux-3.x.git Branch: dmabuf-patch-v1 Earlier versions: RFC: v3 at: https://lkml.org/lkml/2011/12/19/50 v2 at: https://lkml.org/lkml/2011/12/2/53 v1 at: https://lkml.org/lkml/2011/10/11/92 Wish you all happy vacations and a very happy, joyous and prosperous new year 2012 :) Best regards, ~Sumit Semwal History: v4: - Review comments incorporated: - from Konrad Rzeszutek Wilk [https://lkml.org/lkml/2011/12/20/209] - corrected language in some comments - re-ordered struct definitions for readability - added might_sleep() call in dma_buf_map_attachment() wrapper - from Rob Clark [https://lkml.org/lkml/2011/12/23/196] - Made dma-buf EXPERIMENTAL for 1st version. v3: - Review comments incorporated: - from Konrad Rzeszutek Wilk [https://lkml.org/lkml/2011/12/3/45] - replaced BUG_ON with WARN_ON - various places - added some error-checks - replaced EXPORT_SYMBOL with EXPORT_SYMBOL_GPL - some cosmetic / documentation comments - from Arnd Bergmann, Daniel Vetter, Rob Clark [https://lkml.org/lkml/2011/12/5/321] - removed mmap() fop and dma_buf_op, also the sg_sync* operations, and documented that mmap is not allowed for exported buffer - updated documentation to clearly state when migration is allowed - changed kconfig - some error code checks - from Rob Clark [https://lkml.org/lkml/2011/12/5/572] - update documentation to allow map_dma_buf to return -EINTR v2: - Review comments incorporated: - from Tomasz Stanislawski [https://lkml.org/lkml/2011/10/14/136] - kzalloc moved out of critical section - corrected some in-code comments - from Dave Airlie [https://lkml.org/lkml/2011/11/25/123] - from Daniel Vetter and Rob Clark [https://lkml.org/lkml/2011/11/26/53] - use struct sg_table in place of struct scatterlist - rename {get,put}_scatterlist to {map,unmap}_dma_buf - add new wrapper APIs dma_buf_{map,unmap}_attachment for ease of users - documentation updates as per review comments from Randy Dunlap [https://lkml.org/lkml/2011/10/12/439] v1: original Sumit Semwal (3): dma-buf: Introduce dma buffer sharing mechanism dma-buf: Documentation for buffer sharing framework dma-buf: mark EXPERIMENTAL for 1st release. Documentation/dma-buf-sharing.txt | 224 ++++++++++++++++++++++++++++ drivers/base/Kconfig | 11 ++ drivers/base/Makefile | 1 + drivers/base/dma-buf.c | 291 +++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 176 ++++++++++++++++++++++ 5 files changed, 703 insertions(+), 0 deletions(-) create mode 100644 Documentation/dma-buf-sharing.txt create mode 100644 drivers/base/dma-buf.c create mode 100644 include/linux/dma-buf.h -- 1.7.5.4

12 years, 11 months

[PATCH 0/8 v4] ARM: DMA-mapping framework redesign

by Marek Szyprowski

Hello, This is another update on my attempt on DMA-mapping framework redesign for ARM architecture. It includes a few minor changes since last version. We have focused mainly on IOMMU mapper, keeping the DMA-mapping redesign patches almost unchanged. All patches have been now rebased onto v3.2-rc4 kernel + IOMMU/next branch to include latest changes from IOMMU kernel tree. This series also contains support for mapping with pages larger than 4KiB using new, extended IOMMU API. This code has been provided by Andrzej Pietrasiewicz. All the code has been tested on Samsung Exynos4 'UniversalC210' board with IOMMU driver posted by KyongHo Cho. GIT tree will all the patches (including some Samsung Exynos4 stuff): http://git.infradead.org/users/kmpark/linux-samsung/shortlog/refs/heads/3.2… git://git.infradead.org/users/kmpark/linux-samsung 3.2-rc4-dma-v5-samsung History: Initial version of the DMA-mapping redesign patches: http://www.spinics.net/lists/linux-mm/msg21241.html Second version of the patches: http://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000571.html http://lists.linaro.org/pipermail/linaro-mm-sig/2011-September/000577.html Third version of the patches: http://www.spinics.net/lists/linux-mm/msg25490.html TODO: - start the discussion about chaning alloc_coherent into alloc_attrs in dma_map_ops structure. - start the discussion about dma_mmap function - provide documentation for the new dma attributes Best regards -- Marek Szyprowski Samsung Poland R&D Center Patch summary: Marek Szyprowski (8): ARM: dma-mapping: remove offset parameter to prepare for generic dma_ops ARM: dma-mapping: use asm-generic/dma-mapping-common.h ARM: dma-mapping: implement dma sg methods on top of any generic dma ops ARM: dma-mapping: move all dma bounce code to separate dma ops structure ARM: dma-mapping: remove redundant code and cleanup common: dma-mapping: change alloc/free_coherent method to more generic alloc/free_attrs ARM: dma-mapping: use alloc, mmap, free from dma_ops ARM: initial proof-of-concept IOMMU mapper for DMA-mapping arch/arm/Kconfig | 9 + arch/arm/common/dmabounce.c | 78 +++- arch/arm/include/asm/device.h | 4 + arch/arm/include/asm/dma-iommu.h | 36 ++ arch/arm/include/asm/dma-mapping.h | 404 +++++------------ arch/arm/mm/dma-mapping.c | 899 ++++++++++++++++++++++++++++++------ arch/arm/mm/vmregion.h | 2 +- include/linux/dma-attrs.h | 1 + include/linux/dma-mapping.h | 13 +- 9 files changed, 994 insertions(+), 452 deletions(-) create mode 100644 arch/arm/include/asm/dma-iommu.h -- 1.7.1.569.g6f426

12 years, 11 months

[PATCHv18 0/11] Contiguous Memory Allocator

by Marek Szyprowski

Welcome everyone last time in 2011! We finally managed to finish (yet) another release of the Contiguous Memory Allocator patches. This version resolves a lot of issues reported in the previous version and improves the reliability of the memory allocation. The most important changes are code cleanup after a review from Mel Gorman, fixing of the anoying bugs (like HIGHMEM crash on ARM) and adding allocation retry procedure in case of temporary migration fail. This version should finally solve all the issues that are a result of changing the migration code base from memory hotplug to memory compaction. ARM integration code has not been changed since last two versions, it provides implementation of all the ideas that has been discussed during Linaro Sprint meeting. Here are the details: This version provides a solution for complete integration of CMA to DMA mapping subsystem on ARM architecture. The issue caused by double dma pages mapping and possible aliasing in coherent memory mapping has been finally resolved, both for GFP_ATOMIC case (allocations comes from coherent memory pool) and non-GFP_ATOMIC case (allocations comes from CMA managed areas). For coherent, nommu, ARMv4 and ARMv5 systems the current DMA-mapping implementation has been kept. For ARMv6+ systems, CMA has been enabled and a special pool of coherent memory for atomic allocations has been created. The size of this pool defaults to DEFAULT_CONSISTEN_DMA_SIZE/8, but can be changed with coherent_pool kernel parameter (if really required). All atomic allocations are served from this pool. I've did a little simplification here, because there is no separate pool for writecombine memory - such requests are also served from coherent pool. I don't think that such simplification is a problem here - I found no driver that use dma_alloc_writecombine with GFP_ATOMIC flags. All non-atomic allocation are served from CMA area. Kernel mapping is updated to reflect required memory attributes changes. This is possible because during early boot, all CMA area are remapped with 4KiB pages in kernel low-memory. This version have been tested on Samsung S5PC110 based Goni machine and Exynos4 UniversalC210 board with various V4L2 multimedia drivers. Coherent atomic allocations has been tested by manually enabling the dma bounce for the s3c-sdhci device. All patches are prepared for Linux Kernel v3.2-rc7. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. TODO (optional): - implement support for contiguous memory areas placed in HIGHMEM zone - resolve issue with movable pages with pending io operations I would also like to with everyone a Happy New Year! See You again in 2012! Best regards Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v17: <http://www.spinics.net/lists/arm-kernel/msg148499.html> v16: <http://www.spinics.net/lists/linux-mm/msg25066.html> v15: <http://www.spinics.net/lists/linux-mm/msg23365.html> v14: <http://www.spinics.net/lists/linux-media/msg36536.html> v13: (internal, intentionally not released) v12: <http://www.spinics.net/lists/linux-media/msg35674.html> v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v18: 1. Addressed comments and suggestions from Mel Godman related to changes in memory compaction code, most important points: - removed "mm: page_alloc: handle MIGRATE_ISOLATE in free_pcppages_bulk()" and moved all the logic to set_migratetype_isolate - see "mm: page_alloc: set_migratetype_isolate: drain PCP prior to isolating" patch - code in "mm: compaction: introduce isolate_{free,migrate}pages_range()" patch have been simplified and improved - removed "mm: mmzone: introduce zone_pfn_same_memmap()" patch 2. Fixed crash on initialization if HIGHMEM is available on ARM platforms 3. Fixed problems with allocation of contiguous memory if all free pages are occupied by page cache and reclaim is required. 4. Added a workaround for temporary migration failures (now CMA tries to allocate different memory block in such case), what heavily increased reliability of the CMA. 5. Minor cleanup here and there. 6. Rebased onto v3.2-rc7 kernel tree. v17: 1. Replaced whole CMA core memory migration code to the new one kindly provided by Michal Nazarewicz. The new code is based on memory compaction framework not the memory hotplug, like it was before. This change has been suggested by Mel Godman. 2. Addressed most of the comments from Andrew Morton and Mel Gorman in the rest of the CMA code. 3. Fixed broken initialization on ARM systems with DMA zone enabled. 4. Rebased onto v3.2-rc2 kernel. v16: 1. merged a fixup from Michal Nazarewicz to address comments from Dave Hansen about checking if pfns belong to the same memory zone 2. merged a fix from Michal Nazarewicz for incorrect handling of pages which belong to page block that is in MIGRATE_ISOLATE state, in very rare cases the migrate type of page block might have been changed from MIGRATE_CMA to MIGRATE_MOVABLE because of this bug 3. moved some common code to include/asm-generic 4. added support for x86 DMA-mapping framework for pci-dma hardware, CMA can be now even more widely tested on KVM/QEMU and a lot of common x86 boxes 5. rebased onto next-20111005 kernel tree, which includes changes in ARM DMA-mapping subsystem (CONSISTENT_DMA_SIZE removal) 6. removed patch for CMA s5p-fimc device private regions (served only as example) and provided the one that matches real life case - s5p-mfc device v15: 1. fixed calculation of the total memory after activating CMA area (was broken from v12) 2. more code cleanup in drivers/base/dma-contiguous.c 3. added address limit for default CMA area 4. rewrote ARM DMA integration: - removed "ARM: DMA: steal memory for DMA coherent mappings" patch - kept current DMA mapping implementation for coherent, nommu and ARMv4/ARMv5 systems - enabled CMA for all ARMv6+ systems - added separate, small pool for coherent atomic allocations, defaults to CONSISTENT_DMA_SIZE/8, but can be changed with kernel parameter coherent_pool=[size] v14: 1. Merged with "ARM: DMA: steal memory for DMA coherent mappings" patch, added support for GFP_ATOMIC allocations. 2. Added checks for NULL device pointer v13: (internal, intentionally not released) v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: Marek Szyprowski (5): mm: add optional memory reclaim in split_free_page() drivers: add Contiguous Memory Allocator X86: integrate CMA with DMA-mapping subsystem ARM: integrate CMA with DMA-mapping subsystem ARM: Samsung: use CMA for 2 memory banks for s5p-mfc device Michal Nazarewicz (6): mm: page_alloc: set_migratetype_isolate: drain PCP prior to isolating mm: compaction: introduce isolate_{free,migrate}pages_range(). mm: compaction: export some of the functions mm: page_alloc: introduce alloc_contig_range() mm: mmzone: MIGRATE_CMA migration type added mm: page_isolation: MIGRATE_CMA isolation functions added Documentation/kernel-parameters.txt | 9 + arch/Kconfig | 3 + arch/arm/Kconfig | 2 + arch/arm/include/asm/dma-contiguous.h | 16 ++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/kernel/setup.c | 9 +- arch/arm/mm/dma-mapping.c | 368 +++++++++++++++++++++----- arch/arm/mm/init.c | 22 ++- arch/arm/mm/mm.h | 3 + arch/arm/mm/mmu.c | 29 ++- arch/arm/plat-s5p/dev-mfc.c | 51 +--- arch/x86/Kconfig | 1 + arch/x86/include/asm/dma-contiguous.h | 13 + arch/x86/include/asm/dma-mapping.h | 4 + arch/x86/kernel/pci-dma.c | 18 ++- arch/x86/kernel/pci-nommu.c | 8 +- arch/x86/kernel/setup.c | 2 + drivers/base/Kconfig | 89 +++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 404 ++++++++++++++++++++++++++++ include/asm-generic/dma-contiguous.h | 27 ++ include/linux/device.h | 4 + include/linux/dma-contiguous.h | 110 ++++++++ include/linux/mm.h | 2 +- include/linux/mmzone.h | 41 +++- include/linux/page-isolation.h | 27 ++- mm/Kconfig | 2 +- mm/Makefile | 3 +- mm/compaction.c | 467 +++++++++++++++++++-------------- mm/internal.h | 35 +++ mm/memory-failure.c | 2 +- mm/memory_hotplug.c | 6 +- mm/page_alloc.c | 403 +++++++++++++++++++++++++---- mm/page_isolation.c | 15 +- mm/vmstat.c | 1 + 35 files changed, 1773 insertions(+), 425 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 arch/x86/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/asm-generic/dma-contiguous.h create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426

12 years, 11 months

[RFC v2 0/2] Introduce DMA buffer sharing mechanism

by Sumit Semwal

Hello Everyone, This is RFC v2 for DMA buffer sharing mechanism - changes from v1 are in the changelog below. Various subsystems - V4L2, GPU-accessors, DRI to name a few - have felt the need to have a common mechanism to share memory buffers across different devices - ARM, video hardware, GPU. This need comes forth from a variety of use cases including cameras, image processing, video recorders, sound processing, DMA engines, GPU and display buffers, and others. This RFC is an attempt to define such a buffer sharing mechanism- it is the result of discussions from a couple of memory-management mini-summits held by Linaro to understand and address common needs around memory management. [1] A new dma_buf buffer object is added, with operations and API to allow easy sharing of this buffer object across devices. The framework allows: - a new buffer-object to be created with fixed size. - different devices to 'attach' themselves to this buffer, to facilitate backing storage negotiation, using dma_buf_attach() API. - association of a file pointer with each user-buffer and associated allocator-defined operations on that buffer. This operation is called the 'export' operation. - this exported buffer-object to be shared with the other entity by asking for its 'file-descriptor (fd)', and sharing the fd across. - a received fd to get the buffer object back, where it can be accessed using the associated exporter-defined operations. - the exporter and user to share the scatterlist using map_dma_buf and unmap_dma_buf operations. Documentation present in the patch-set gives more details. This is based on design suggestions from many people at the mini-summits, most notably from Arnd Bergmann <arnd(a)arndb.de>, Rob Clark <rob(a)ti.com> and Daniel Vetter <daniel(a)ffwll.ch>. The implementation is inspired from proof-of-concept patch-set from Tomasz Stanislawski <t.stanislaws(a)samsung.com>, who demonstrated buffer sharing between two v4l2 devices. [2] References: [1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement [2]: http://lwn.net/Articles/454389 Patchset based on top of 3.2-rc3, the current version can be found at http://git.linaro.org/gitweb?p=people/sumitsemwal/linux-3.x.git Branch: dma-buf-upstr-v2 Earlier version at: https://lkml.org/lkml/2011/10/11/92 Best regards, ~Sumit Semwal History: v2: - Review comments incorporated: - from Tomasz Stanislawski [https://lkml.org/lkml/2011/10/14/136] - kzalloc moved out of critical section - corrected some in-code comments - from Dave Airlie [https://lkml.org/lkml/2011/11/25/123] - from Daniel Vetter and Rob Clark [https://lkml.org/lkml/2011/11/26/53] - use struct sg_table in place of struct scatterlist - rename {get,put}_scatterlist to {map,unmap}_dma_buf - add new wrapper APIs dma_buf_{map,unmap}_attachment for ease of users - documentation updates as per review comments from Randy Dunlap [https://lkml.org/lkml/2011/10/12/439] v1: original Sumit Semwal (2): dma-buf: Introduce dma buffer sharing mechanism dma-buf: Documentation for buffer sharing framework Documentation/dma-buf-sharing.txt | 223 ++++++++++++++++++++++++++++ drivers/base/Kconfig | 10 ++ drivers/base/Makefile | 1 + drivers/base/dma-buf.c | 290 +++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 176 ++++++++++++++++++++++ 5 files changed, 700 insertions(+), 0 deletions(-) create mode 100644 Documentation/dma-buf-sharing.txt create mode 100644 drivers/base/dma-buf.c create mode 100644 include/linux/dma-buf.h -- 1.7.4.1

12 years, 11 months

[RFC v3 0/2] Introduce DMA buffer sharing mechanism

by Sumit Semwal

Hello Everyone, This is RFC v3 for DMA buffer sharing mechanism - changes from v2 are in the changelog below. Various subsystems - V4L2, GPU-accessors, DRI to name a few - have felt the need to have a common mechanism to share memory buffers across different devices - ARM, video hardware, GPU. This need comes forth from a variety of use cases including cameras, image processing, video recorders, sound processing, DMA engines, GPU and display buffers, and others. This RFC is an attempt to define such a buffer sharing mechanism- it is the result of discussions from a couple of memory-management mini-summits held by Linaro to understand and address common needs around memory management. [1] A new dma_buf buffer object is added, with operations and API to allow easy sharing of this buffer object across devices. The framework allows: - a new buffer-object to be created with fixed size. - different devices to 'attach' themselves to this buffer, to facilitate backing storage negotiation, using dma_buf_attach() API. - association of a file pointer with each user-buffer and associated allocator-defined operations on that buffer. This operation is called the 'export' operation. - this exported buffer-object to be shared with the other entity by asking for its 'file-descriptor (fd)', and sharing the fd across. - a received fd to get the buffer object back, where it can be accessed using the associated exporter-defined operations. - the exporter and user to share the scatterlist using map_dma_buf and unmap_dma_buf operations. Documentation present in the patch-set gives more details. This is based on design suggestions from many people at the mini-summits, most notably from Arnd Bergmann <arnd(a)arndb.de>, Rob Clark <rob(a)ti.com> and Daniel Vetter <daniel(a)ffwll.ch>. The implementation is inspired from proof-of-concept patch-set from Tomasz Stanislawski <t.stanislaws(a)samsung.com>, who demonstrated buffer sharing between two v4l2 devices. [2] References: [1]: https://wiki.linaro.org/OfficeofCTO/MemoryManagement [2]: http://lwn.net/Articles/454389 Patchset based on top of 3.2-rc3, the current version can be found at http://git.linaro.org/gitweb?p=people/sumitsemwal/linux-3.x.git Branch: dma-buf-upstr-v2 Earlier versions: v2 at: https://lkml.org/lkml/2011/12/2/53 v1 at: https://lkml.org/lkml/2011/10/11/92 Best regards, ~Sumit Semwal History: v3: - Review comments incorporated: - from Konrad Rzeszutek Wilk [https://lkml.org/lkml/2011/12/3/45] - replaced BUG_ON with WARN_ON - various places - added some error-checks - replaced EXPORT_SYMBOL with EXPORT_SYMBOL_GPL - some cosmetic / documentation comments - from Arnd Bergmann, Daniel Vetter, Rob Clark [https://lkml.org/lkml/2011/12/5/321] - removed mmap() fop and dma_buf_op, also the sg_sync* operations, and documented that mmap is not allowed for exported buffer - updated documentation to clearly state when migration is allowed - changed kconfig - some error code checks - from Rob Clark [https://lkml.org/lkml/2011/12/5/572] - update documentation to allow map_dma_buf to return -EINTR v2: - Review comments incorporated: - from Tomasz Stanislawski [https://lkml.org/lkml/2011/10/14/136] - kzalloc moved out of critical section - corrected some in-code comments - from Dave Airlie [https://lkml.org/lkml/2011/11/25/123] - from Daniel Vetter and Rob Clark [https://lkml.org/lkml/2011/11/26/53] - use struct sg_table in place of struct scatterlist - rename {get,put}_scatterlist to {map,unmap}_dma_buf - add new wrapper APIs dma_buf_{map,unmap}_attachment for ease of users - documentation updates as per review comments from Randy Dunlap [https://lkml.org/lkml/2011/10/12/439] v1: original Sumit Semwal (2): dma-buf: Introduce dma buffer sharing mechanism dma-buf: Documentation for buffer sharing framework Documentation/dma-buf-sharing.txt | 222 ++++++++++++++++++++++++++++ drivers/base/Kconfig | 10 ++ drivers/base/Makefile | 1 + drivers/base/dma-buf.c | 289 +++++++++++++++++++++++++++++++++++++ include/linux/dma-buf.h | 172 ++++++++++++++++++++++ 5 files changed, 694 insertions(+), 0 deletions(-) create mode 100644 Documentation/dma-buf-sharing.txt create mode 100644 drivers/base/dma-buf.c create mode 100644 include/linux/dma-buf.h -- 1.7.4.1

12 years, 11 months

[ACTIVITY] Status of memory management closing 11.12

by Ilias Biris

Hi folks, I went ahead and checked what is the status of the UMM effort as 2011 is closing to an end. What follows is my attempt to summarise the status, collating the pieces from the latest announcements and changelogs and having discussed it briefly with Jesse and Rob. Feel free to comment if there is something missing or not correct: A. CMA - Contiguous memory allocator. This is in its v17 incarnation at the moment (a v18 is in preparation but not released yet). v17 shares the code with memory compaction subsystem, not the hotplug like it was before (change has been suggested by Mel Gorman) and there are also a few fixes here and there, like addressing most of the comments from Andrew Morton and Mel Gorman in the rest of the CMA code, fixing broken initialization on ARM systems with DMA zone enabled and rebasing the code on v3.2-rc2 kernel. An issue has been noted in linaro-dev from the TI landing team : without any highmem the code is working great, but with HIGHMEM inclusion of the CMA v17 consistently causes failure during DMA init. This is expected to be fixed soon (perhaps in v18?). In meantime it is suggested using 2G/2G memory split as a workaround (Kernel Features -> Memory split -> 2G/2G user/kernel split). B. dma mapping API - DMA-mapping framework redesign for ARM architecture: this is in the v4 now. It includes a few minor changes since last version. The changes are mainly on the IOMMU mapper, keeping the DMA-mapping redesign patches almost unchanged. The code is rebased onto v3.2-rc4 kernel + IOMMU/next branch to include latest changes from IOMMU kernel tree. This series also contains support for mapping with pages larger than 4KiB using new, extended IOMMU API, and did a general cleanup of the DMA mapping implementation. However it seems that this patchset "attempts to fix everyone at once". It has been suggested that instead of trying to do that the implementation should give sufficient transition period - for example just adding the new methods now and only removing them in the following merge window when all the architectures have had a chance to migrate. C. dmabuf - a DMA-buf object sharing framework: this is now in its 3rd version. The newest version incorporates changes as requested during the review, such as - replacing BUG_ON with WARN_ON at various places, removing mmap() fop and dma_buf_op, also the sg_sync* operations, and documenting that mmap is not allowed for exported buffer, adding error checks, replacing EXPORT_SYMBOL with EXPORT_SYMBOL_GPL and fixing some cosmetic/documentation items. There are still some items under discusion such as userspace mmap support, more advanced (and more strictly specified) coherency models and shared infrastructure for implementing exporters. However, there is a suggestion that these items will become much clearer once we have a few example drivers at hand and a better understanding of what cases need to be handled better. D. Finally some repositories - where can you find the code to try it out: * git://git.linaro.org/people/jessebarker/linaro-mm-sig/linux.git contains (for the moment) 6 branches: + cma-v17 == unadulterated v3.2-rc4 + cma v17 patchset + dma-mapping-v4 == unadulterated v3.2-rc4 + dma-mapping v4 patchset + android-cma-v17 == john stultz's androidization tree based upon unadulterated v3.2-rc4 + cma v17 patchset + android-dma-mapping-v4 == john stultz's androidization tree based upon unadulterated v3.2-rc4 + dma-mapping v4 patchset Also note these repos: - https://github.com/robclark/kernel-omap4/commits/drmplane-dmabuf contains patches to enable sharing of buffers between drm and v4l2, Rob commented that it isn't really identified yet which tree to push dmabuf through.. airlied has volunteered to push via drm tree, which is ok - git://git.linaro.org/people/bgaignard/linux-snowball-cma-test.git contains a first version of the CMA testing scripts for LAVA (snowball specific at least for now) Best regards, -- Ilias Biris ilias.biris(a)linaro.org Project Manager, Linaro M: +358504839608, IRC: ibiris Skype: ilias_biris Linaro.org│ Open source software for ARM SoCs

12 years, 12 months

Re: [Linaro-mm-sig] [PATCH v2 1/2] [RFC] ARM: IOMMU: Tegra20: iommu_ops for GART driver

by Hiroshi Doyu

Hi, One question is inlined below: From: Hiroshi Doyu <hdoyu(a)nvidia.com> Subject: [PATCH v2 1/2] [RFC] ARM: IOMMU: Tegra20: iommu_ops for GART driver Date: Thu, 15 Dec 2011 14:11:29 +0100 Message-ID: <1323954690-7000-2-git-send-email-hdoyu(a)nvidia.com> > Tegra 20 IOMMU H/W, GART (Graphics Address Relocation Table). This > patch implements struct iommu_ops for GART for the upper IOMMU API. > > This H/W module supports only single virtual address space(domain), > and manages a single level 1-to-1 mapping H/W translation page table. > > Signed-off-by: Hiroshi DOYU <hdoyu(a)nvidia.com> > --- > drivers/iommu/Kconfig | 11 + > drivers/iommu/Makefile | 1 + > drivers/iommu/tegra-gart.c | 451 ++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 463 insertions(+), 0 deletions(-) > create mode 100644 drivers/iommu/tegra-gart.c > .... > + > +struct gart_device { > + void __iomem *regs; > + u32 *savedata; > + u32 page_count; /* total remappable size */ > + dma_addr_t iovmm_base; /* offset to apply to vmm_area */ > + spinlock_t pte_lock; /* for pagetable */ > + struct list_head client; > + spinlock_t client_lock; /* for client list */ > + struct device *dev; > +}; > + > +static struct gart_device *gart_handle; /* unique for a system */ ^^^^^^^^^^^ ..... > + > +static int gart_iommu_domain_init(struct iommu_domain *domain) > +{ > + domain->priv = gart_handle; ^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + pr_debug("gart@%p\n", gart_handle); > + return 0; > +} In the above, the global pointer is used to pass gart_device to set it in dmain->priv. It works with a single gart_device, but not with multiple gart_devices. This is too bad, I know;). I guess that this can be solved with device tree info where a client device is set as a child of gart_device at device registration. Is this the right way from IOMMU API POV? for (i = 0; i < ARRAY_SIZE(dmaapi_dummy_device); i++) { int err; struct platform_device *pdev = &dmaapi_dummy_device[i]; pdev->dev.platform_data = (void *)dummy_hwgrp_map[i]; pdev->dev.parent = &tegra_gart_device; ^^^^^^^^^^^^^^^^^^^ err = platform_device_register(pdev);

13 years

Re: [Linaro-mm-sig] [PATCH v2 1/2] [RFC] ARM: IOMMU: Tegra20: iommu_ops for GART driver

by Hiroshi Doyu

Hi Joerg, Thank you for your quick review. From: Joerg Roedel <joerg.roedel(a)amd.com> Subject: Re: [PATCH v2 1/2] [RFC] ARM: IOMMU: Tegra20: iommu_ops for GART driver Date: Fri, 16 Dec 2011 16:43:31 +0100 Message-ID: <20111216154331.GD29877(a)amd.com> > On Thu, Dec 15, 2011 at 03:11:29PM +0200, Hiroshi DOYU wrote: > > Tegra 20 IOMMU H/W, GART (Graphics Address Relocation Table). This > > patch implements struct iommu_ops for GART for the upper IOMMU API. > > > > This H/W module supports only single virtual address space(domain), > > and manages a single level 1-to-1 mapping H/W translation page table. > > > > Signed-off-by: Hiroshi DOYU <hdoyu(a)nvidia.com> > > --- > > drivers/iommu/Kconfig | 11 + > > drivers/iommu/Makefile | 1 + > > drivers/iommu/tegra-gart.c | 451 ++++++++++++++++++++++++++++++++++++++++++++ > > The code looks good in general. Thanks. > I think we need to extend the IOMMU-API > a little bit to better support GART IOMMUs. A user of the IOMMU-API > should be able to get the information about the iova-base and size of > the aperture for example. These extensions will be beneficial for > porting other GART-like driver to the IOMMU-API too. is it similar to how ".pgsize_bitmap" is passed? > > > Joerg > > -- > AMD Operating System Research Center > > Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach > General Managers: Alberto Bozzo, Andrew Bowd > Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 >

13 years

[PATCHv17 0/11] Contiguous Memory Allocator

by Marek Szyprowski

Welcome everyone once again, This is yet another release of the Contiguous Memory Allocator patches. This version is mainly a result of the discussion on Kernel Summit in Prague. The main change is completely different code base for the migration feature of the CMA. Now it shares the code with memory compaction subsystem, not the hotplug like it was before. This code has been kindly provided by Michal Nazarewicz. There are also a few fixes here and there, see changelog for the details. Please notice that this patch series is aimed to start further discussion. There are still few issues that need to be resolved before CMA will be really ready. The most hot problem is the issue with movable pages that causes migration to fail from time to time. Our investigation leads us to the point that these rare pages cannot be migrated because there are some pending io operations on them. ARM integration code has not been changed since last version, it provides implementation of all the ideas that has been discussed during Linaro Sprint meeting. Here are the details: This version provides a solution for complete integration of CMA to DMA mapping subsystem on ARM architecture. The issue caused by double dma pages mapping and possible aliasing in coherent memory mapping has been finally resolved, both for GFP_ATOMIC case (allocations comes from coherent memory pool) and non-GFP_ATOMIC case (allocations comes from CMA managed areas). For coherent, nommu, ARMv4 and ARMv5 systems the current DMA-mapping implementation has been kept. For ARMv6+ systems, CMA has been enabled and a special pool of coherent memory for atomic allocations has been created. The size of this pool defaults to DEFAULT_CONSISTEN_DMA_SIZE/8, but can be changed with coherent_pool kernel parameter (if really required). All atomic allocations are served from this pool. I've did a little simplification here, because there is no separate pool for writecombine memory - such requests are also served from coherent pool. I don't think that such simplification is a problem here - I found no driver that use dma_alloc_writecombine with GFP_ATOMIC flags. All non-atomic allocation are served from CMA area. Kernel mapping is updated to reflect required memory attributes changes. This is possible because during early boot, all CMA area are remapped with 4KiB pages in kernel low-memory. This version have been tested on Samsung S5PC110 based Goni machine and Exynos4 UniversalC210 board with various V4L2 multimedia drivers. Coherent atomic allocations has been tested by manually enabling the dma bounce for the s3c-sdhci device. All patches are prepared for Linux Kernel v3.2-rc2. A few words for these who see CMA for the first time: The Contiguous Memory Allocator (CMA) makes it possible for device drivers to allocate big contiguous chunks of memory after the system has booted. The main difference from the similar frameworks is the fact that CMA allows to transparently reuse memory region reserved for the big chunk allocation as a system memory, so no memory is wasted when no big chunk is allocated. Once the alloc request is issued, the framework will migrate system pages to create a required big chunk of physically contiguous memory. For more information you can refer to nice LWN articles: http://lwn.net/Articles/447405/ and http://lwn.net/Articles/450286/ as well as links to previous versions of the CMA framework. The CMA framework has been initially developed by Michal Nazarewicz at Samsung Poland R&D Center. Since version 9, I've taken over the development, because Michal has left the company. TODO (optional): - implement support for contiguous memory areas placed in HIGHMEM zone - resolve issue with movable pages with pending io operations Best regards Marek Szyprowski Samsung Poland R&D Center Links to previous versions of the patchset: v16: <http://www.spinics.net/lists/linux-mm/msg25066.html> v15: <http://www.spinics.net/lists/linux-mm/msg23365.html> v14: <http://www.spinics.net/lists/linux-media/msg36536.html> v13: (internal, intentionally not released) v12: <http://www.spinics.net/lists/linux-media/msg35674.html> v11: <http://www.spinics.net/lists/linux-mm/msg21868.html> v10: <http://www.spinics.net/lists/linux-mm/msg20761.html> v9: <http://article.gmane.org/gmane.linux.kernel.mm/60787> v8: <http://article.gmane.org/gmane.linux.kernel.mm/56855> v7: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v6: <http://article.gmane.org/gmane.linux.kernel.mm/55626> v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: <http://article.gmane.org/gmane.linux.kernel.mm/52010> v3: <http://article.gmane.org/gmane.linux.kernel.mm/51573> v2: <http://article.gmane.org/gmane.linux.kernel.mm/50986> v1: <http://article.gmane.org/gmane.linux.kernel.mm/50669> Changelog: v17: 1. Replaced whole CMA core memory migration code to the new one kindly provided by Michal Nazarewicz. The new code is based on memory compaction framework not the memory hotplug, like it was before. This change has been suggested by Mel Godman. 2. Addressed most of the comments from Andrew Morton and Mel Gorman in the rest of the CMA code. 3. Fixed broken initialization on ARM systems with DMA zone enabled. 4. Rebased onto v3.2-rc2 kernel. v16: 1. merged a fixup from Michal Nazarewicz to address comments from Dave Hansen about checking if pfns belong to the same memory zone 2. merged a fix from Michal Nazarewicz for incorrect handling of pages which belong to page block that is in MIGRATE_ISOLATE state, in very rare cases the migrate type of page block might have been changed from MIGRATE_CMA to MIGRATE_MOVABLE because of this bug 3. moved some common code to include/asm-generic 4. added support for x86 DMA-mapping framework for pci-dma hardware, CMA can be now even more widely tested on KVM/QEMU and a lot of common x86 boxes 5. rebased onto next-20111005 kernel tree, which includes changes in ARM DMA-mapping subsystem (CONSISTENT_DMA_SIZE removal) 6. removed patch for CMA s5p-fimc device private regions (served only as example) and provided the one that matches real life case - s5p-mfc device v15: 1. fixed calculation of the total memory after activating CMA area (was broken from v12) 2. more code cleanup in drivers/base/dma-contiguous.c 3. added address limit for default CMA area 4. rewrote ARM DMA integration: - removed "ARM: DMA: steal memory for DMA coherent mappings" patch - kept current DMA mapping implementation for coherent, nommu and ARMv4/ARMv5 systems - enabled CMA for all ARMv6+ systems - added separate, small pool for coherent atomic allocations, defaults to CONSISTENT_DMA_SIZE/8, but can be changed with kernel parameter coherent_pool=[size] v14: 1. Merged with "ARM: DMA: steal memory for DMA coherent mappings" patch, added support for GFP_ATOMIC allocations. 2. Added checks for NULL device pointer v13: (internal, intentionally not released) v12: 1. Fixed 2 nasty bugs in dma-contiguous allocator: - alignment argument was not passed correctly - range for dma_release_from_contiguous was not checked correctly 2. Added support for architecture specfic dma_contiguous_early_fixup() function 3. CMA and DMA-mapping integration for ARM architechture has been rewritten to take care of the memory aliasing issue that might happen for newer ARM CPUs (mapping of the same pages with different cache attributes is forbidden). TODO: add support for GFP_ATOMIC allocations basing on the "ARM: DMA: steal memory for DMA coherent mappings" patch and implement support for contiguous memory areas that are placed in HIGHMEM zone v11: 1. Removed genalloc usage and replaced it with direct calls to bitmap_* functions, dropped patches that are not needed anymore (genalloc extensions) 2. Moved all contiguous area management code from mm/cma.c to drivers/base/dma-contiguous.c 3. Renamed cm_alloc/free to dma_alloc/release_from_contiguous 4. Introduced global, system wide (default) contiguous area configured with kernel config and kernel cmdline parameters 5. Simplified initialization to just one function: dma_declare_contiguous() 6. Added example of device private memory contiguous area v10: 1. Rebased onto 3.0-rc2 and resolved all conflicts 2. Simplified CMA to be just a pure memory allocator, for use with platfrom/bus specific subsystems, like dma-mapping. Removed all device specific functions are calls. 3. Integrated with ARM DMA-mapping subsystem. 4. Code cleanup here and there. 5. Removed private context support. v9: 1. Rebased onto 2.6.39-rc1 and resolved all conflicts 2. Fixed a bunch of nasty bugs that happened when the allocation failed (mainly kernel oops due to NULL ptr dereference). 3. Introduced testing code: cma-regions compatibility layer and videobuf2-cma memory allocator module. v8: 1. The alloc_contig_range() function has now been separated from CMA and put in page_allocator.c. This function tries to migrate all LRU pages in specified range and then allocate the range using alloc_contig_freed_pages(). 2. Support for MIGRATE_CMA has been separated from the CMA code. I have not tested if CMA works with ZONE_MOVABLE but I see no reasons why it shouldn't. 3. I have added a @private argument when creating CMA contexts so that one can reserve memory and not share it with the rest of the system. This way, CMA acts only as allocation algorithm. v7: 1. A lot of functionality that handled driver->allocator_context mapping has been removed from the patchset. This is not to say that this code is not needed, it's just not worth posting everything in one patchset. Currently, CMA is "just" an allocator. It uses it's own migratetype (MIGRATE_CMA) for defining ranges of pageblokcs which behave just like ZONE_MOVABLE but dispite the latter can be put in arbitrary places. 2. The migration code that was introduced in the previous version actually started working. v6: 1. Most importantly, v6 introduces support for memory migration. The implementation is not yet complete though. Migration support means that when CMA is not using memory reserved for it, page allocator can allocate pages from it. When CMA wants to use the memory, the pages have to be moved and/or evicted as to make room for CMA. To make it possible it must be guaranteed that only movable and reclaimable pages are allocated in CMA controlled regions. This is done by introducing a MIGRATE_CMA migrate type that guarantees exactly that. Some of the migration code is "borrowed" from Kamezawa Hiroyuki's alloc_contig_pages() implementation. The main difference is that thanks to MIGRATE_CMA migrate type CMA assumes that memory controlled by CMA are is always movable or reclaimable so that it makes allocation decisions regardless of the whether some pages are actually allocated and migrates them if needed. The most interesting patches from the patchset that implement the functionality are: 09/13: mm: alloc_contig_free_pages() added 10/13: mm: MIGRATE_CMA migration type added 11/13: mm: MIGRATE_CMA isolation functions added 12/13: mm: cma: Migration support added [wip] Currently, kernel panics in some situations which I am trying to investigate. 2. cma_pin() and cma_unpin() functions has been added (after a conversation with Johan Mossberg). The idea is that whenever hardware does not use the memory (no transaction is on) the chunk can be moved around. This would allow defragmentation to be implemented if desired. No defragmentation algorithm is provided at this time. 3. Sysfs support has been replaced with debugfs. I always felt unsure about the sysfs interface and when Greg KH pointed it out I finally got to rewrite it to debugfs. v5: (intentionally left out as CMA v5 was identical to CMA v4) v4: 1. The "asterisk" flag has been removed in favour of requiring that platform will provide a "*=<regions>" rule in the map attribute. 2. The terminology has been changed slightly renaming "kind" to "type" of memory. In the previous revisions, the documentation indicated that device drivers define memory kinds and now, v3: 1. The command line parameters have been removed (and moved to a separate patch, the fourth one). As a consequence, the cma_set_defaults() function has been changed -- it no longer accepts a string with list of regions but an array of regions. 2. The "asterisk" attribute has been removed. Now, each region has an "asterisk" flag which lets one specify whether this region should by considered "asterisk" region. 3. SysFS support has been moved to a separate patch (the third one in the series) and now also includes list of regions. v2: 1. The "cma_map" command line have been removed. In exchange, a SysFS entry has been created under kernel/mm/contiguous. The intended way of specifying the attributes is a cma_set_defaults() function called by platform initialisation code. "regions" attribute (the string specified by "cma" command line parameter) can be overwritten with command line parameter; the other attributes can be changed during run-time using the SysFS entries. 2. The behaviour of the "map" attribute has been modified slightly. Currently, if no rule matches given device it is assigned regions specified by the "asterisk" attribute. It is by default built from the region names given in "regions" attribute. 3. Devices can register private regions as well as regions that can be shared but are not reserved using standard CMA mechanisms. A private region has no name and can be accessed only by devices that have the pointer to it. 4. The way allocators are registered has changed. Currently, a cma_allocator_register() function is used for that purpose. Moreover, allocators are attached to regions the first time memory is registered from the region or when allocator is registered which means that allocators can be dynamic modules that are loaded after the kernel booted (of course, it won't be possible to allocate a chunk of memory from a region if allocator is not loaded). 5. Index of new functions: +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, size_t size, + dma_addr_t alignment) +static inline int +cma_info_about(struct cma_info *info, const const char *regions) +int __must_check cma_region_register(struct cma_region *reg); +dma_addr_t __must_check +cma_alloc_from_region(struct cma_region *reg, + size_t size, dma_addr_t alignment); +static inline dma_addr_t __must_check +cma_alloc_from(const char *regions, + size_t size, dma_addr_t alignment); +int cma_allocator_register(struct cma_allocator *alloc); Patches in this patchset: Marek Szyprowski (4): drivers: add Contiguous Memory Allocator X86: integrate CMA with DMA-mapping subsystem ARM: integrate CMA with DMA-mapping subsystem ARM: Samsung: use CMA for 2 memory banks for s5p-mfc device Michal Nazarewicz (7): mm: page_alloc: handle MIGRATE_ISOLATE in free_pcppages_bulk() mm: compaction: introduce isolate_{free,migrate}pages_range(). mm: mmzone: introduce zone_pfn_same_memmap() mm: compaction: export some of the functions mm: page_alloc: introduce alloc_contig_range() mm: mmzone: MIGRATE_CMA migration type added mm: page_isolation: MIGRATE_CMA isolation functions added Documentation/kernel-parameters.txt | 9 + arch/Kconfig | 3 + arch/arm/Kconfig | 2 + arch/arm/include/asm/dma-contiguous.h | 16 ++ arch/arm/include/asm/mach/map.h | 1 + arch/arm/kernel/setup.c | 8 +- arch/arm/mm/dma-mapping.c | 368 +++++++++++++++++++++++++------ arch/arm/mm/init.c | 20 ++- arch/arm/mm/mm.h | 3 + arch/arm/mm/mmu.c | 29 ++- arch/arm/plat-s5p/dev-mfc.c | 51 +---- arch/x86/Kconfig | 1 + arch/x86/include/asm/dma-contiguous.h | 13 + arch/x86/include/asm/dma-mapping.h | 4 + arch/x86/kernel/pci-dma.c | 18 ++- arch/x86/kernel/pci-nommu.c | 8 +- arch/x86/kernel/setup.c | 2 + drivers/base/Kconfig | 89 ++++++++ drivers/base/Makefile | 1 + drivers/base/dma-contiguous.c | 396 +++++++++++++++++++++++++++++++++ include/asm-generic/dma-contiguous.h | 27 +++ include/linux/device.h | 4 + include/linux/dma-contiguous.h | 110 +++++++++ include/linux/mmzone.h | 57 ++++- include/linux/page-isolation.h | 27 ++- mm/Kconfig | 2 +- mm/Makefile | 3 +- mm/compaction.c | 230 +++++++++++-------- mm/internal.h | 35 +++ mm/memory-failure.c | 2 +- mm/memory_hotplug.c | 6 +- mm/page_alloc.c | 315 ++++++++++++++++++++++++-- mm/page_isolation.c | 15 +- 33 files changed, 1591 insertions(+), 284 deletions(-) create mode 100644 arch/arm/include/asm/dma-contiguous.h create mode 100644 arch/x86/include/asm/dma-contiguous.h create mode 100644 drivers/base/dma-contiguous.c create mode 100644 include/asm-generic/dma-contiguous.h create mode 100644 include/linux/dma-contiguous.h -- 1.7.1.569.g6f426

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Linaro-mm-sig December 2011