Fix build warning in __dma_alloc() as below:
arch/arm/mm/dma-mapping.c: In function '__dma_alloc':
arch/arm/mm/dma-mapping.c:653:29: warning: 'page' may be used uninitialized in this function [-Wuninitialized]
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Remove arch_is_coherent() from iommu dma ops and implement separate
coherent ops functions.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
arch_is_coherent is problematic as it is a global symbol. This
doesn't work for multi-platform kernels or platforms which can support
per device coherent DMA.
This adds arm_coherent_dma_ops to be used for devices which connected
coherently (i.e. to the ACP port on Cortex-A9 or A15). The arm_dma_ops
are modified at boot when arch_is_coherent is true.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
With many IOMMU'able devices, console gets noisy.
Tegra30 has a few dozen of IOMMU'able devices.
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Skip unnecessary operations if order == 0. A little bit easier to
read.
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
When either of __alloc_from_contiguous or __alloc_remap_buffer fails
to provide a valid pointer, allocated memory is freed up and an error
is returned. 'pages' was however not freed before returning error.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
The __free_from_pool() function was changed in
e9da6e9905. Unfortunately, the test that
checks whether the provided (start,size) is within the DMA pool has
been improperly modified. It used to be:
if (start < coherent_head.vm_start || end > coherent_head.vm_end)
Where coherent_head.vm_end was non-inclusive (i.e, it did not include
the first byte after the pool). The test has been changed to:
if (start < pool->vaddr || start > pool->vaddr + pool->size)
So now pool->vaddr + pool->size is inclusive (i.e, it includes the
first byte after the pool), so the test should be >= instead of >.
This bug causes the following message when freeing the *first* DMA
coherent buffer that has been allocated, because its virtual address
is exactly equal to pool->vaddr + pool->size :
WARNING: at /home/thomas/projets/linux-2.6/arch/arm/mm/dma-mapping.c:463 __free_from_pool+0xa4/0xc0()
freeing wrong coherent size from pool
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Lior Amsalem <alior@marvell.com>
Cc: Maen Suleiman <maen@marvell.com>
Cc: Tawfik Bayouk <tawfik@marvell.com>
Cc: Shadi Ammouri <shadi@marvell.com>
Cc: Eran Ben-Avi <benavi@marvell.com>
Cc: Yehuda Yitschak <yehuday@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>
[m.szyprowski: rebased onto v3.6-rc5 and resolved conflict]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Make use of the same atomic pool as DMA does, and skip a kernel page
mapping which can involve sleep'able operations at allocating a kernel
page table.
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Support atomic allocation in __iommu_get_pages().
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
[moved __atomic_get_pages() under #ifdef CONFIG_ARM_DMA_USE_IOMMU
to avoid unused fuction warning for no-IOMMU case]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Check the given range("start", "size") is included in "atomic_pool" or not.
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
struct page **pages is necessary to align with non atomic path in
__iommu_get_pages(). atomic_pool() has the intialized **pages instead
of just *page.
Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Print a loud warning when system runs out of memory from atomic DMA
coherent pool to let users notice the potential problem.
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Some platforms might require to increase atomic coherent pool to make
sure that their device will be able to allocate all their buffers from
atomic context. This function can be also used to decrease atomic
coherent pool size if coherent allocations are not used for the given
sub-platform.
Suggested-by: Josh Coombs <josh.coombs@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
The alignment mask is calculated incorrectly. Fixing the calculation
makes strange hangs/lockups disappear during the boot with Amstrad E3
and 3.6-rc1 kernel.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fix dma_contiguous_remap() so that it continues through all the
regions, even after encountering one that is outside lowmem.
Without this change, if you have two CMA regions, the first outside
lowmem and the seocnd inside lowmem, only the second one will get
set up in the MMU. Data written to that region then doesn't get
automatically flushed from the cache into memory.
Signed-off-by: Chris Brand <cbrand@broadcom.com>
[extended patch subject with 'fix' word]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Pull DMA-mapping updates from Marek Szyprowski:
"Those patches are continuation of my earlier work.
They contains extensions to DMA-mapping framework to remove limitation
of the current ARM implementation (like limited total size of DMA
coherent/write combine buffers), improve performance of buffer sharing
between devices (attributes to skip cpu cache operations or creation
of additional kernel mapping for some specific use cases) as well as
some unification of the common code for dma_mmap_attrs() and
dma_mmap_coherent() functions. All extensions have been implemented
and tested for ARM architecture."
* 'for-linus-for-3.6-rc1' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
ARM: dma-mapping: add support for DMA_ATTR_SKIP_CPU_SYNC attribute
common: DMA-mapping: add DMA_ATTR_SKIP_CPU_SYNC attribute
ARM: dma-mapping: add support for dma_get_sgtable()
common: dma-mapping: introduce dma_get_sgtable() function
ARM: dma-mapping: add support for DMA_ATTR_NO_KERNEL_MAPPING attribute
common: DMA-mapping: add DMA_ATTR_NO_KERNEL_MAPPING attribute
common: dma-mapping: add support for generic dma_mmap_* calls
ARM: dma-mapping: fix error path for memory allocation failure
ARM: dma-mapping: add more sanity checks in arm_dma_mmap()
ARM: dma-mapping: remove custom consistent dma region
mm: vmalloc: use const void * for caller argument
scatterlist: add sg_alloc_table_from_pages function
This patch adds support for DMA_ATTR_SKIP_CPU_SYNC attribute for
dma_(un)map_(single,page,sg) functions family. It lets dma mapping clients
to create a mapping for the buffer for the given device without performing
a CPU cache synchronization. CPU cache synchronization can be skipped for
the buffers which it is known that they are already in 'device' domain (CPU
caches have been already synchronized or there are only coherent mappings
for the buffer). For advanced users only, please use it with care.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
This patch adds support for dma_get_sgtable() function which is required
to let drivers to share the buffers allocated by DMA-mapping subsystem.
Generic implementation based on virt_to_page() is not suitable for ARM
dma-mapping subsystem.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
This patch adds support for DMA_ATTR_NO_KERNEL_MAPPING attribute for
IOMMU allocations, what let drivers to save precious kernel virtual
address space for large buffers that are intended to be accessed only
from userspace.
This patch is heavily based on initial work kindly provided by Abhinav
Kochhar <abhinav.k@samsung.com>.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
This patch fixes incorrect check in error path. When the allocation of
first page fails, the kernel ops appears due to accessing -1 element of
the pages array.
Reported-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Add some sanity checks and forbid mmaping of buffers into vma areas larger
than allocated dma buffer.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This patch changes dma-mapping subsystem to use generic vmalloc areas
for all consistent dma allocations. This increases the total size limit
of the consistent allocations and removes platform hacks and a lot of
duplicated code.
Atomic allocations are served from special pool preallocated on boot,
because vmalloc areas cannot be reliably created in atomic context.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
WARNING: at mm/vmalloc.c:1471 __iommu_free_buffer+0xcc/0xd0()
Trying to vfree() nonexistent vm area (ef095000)
Modules linked in:
[<c0015a18>] (unwind_backtrace+0x0/0xfc) from [<c0025a94>] (warn_slowpath_common+0x54/0x64)
[<c0025a94>] (warn_slowpath_common+0x54/0x64) from [<c0025b38>] (warn_slowpath_fmt+0x30/0x40)
[<c0025b38>] (warn_slowpath_fmt+0x30/0x40) from [<c0016de0>] (__iommu_free_buffer+0xcc/0xd0)
[<c0016de0>] (__iommu_free_buffer+0xcc/0xd0) from [<c0229a5c>] (exynos_drm_free_buf+0xe4/0x138)
[<c0229a5c>] (exynos_drm_free_buf+0xe4/0x138) from [<c022b358>] (exynos_drm_gem_destroy+0x80/0xfc)
[<c022b358>] (exynos_drm_gem_destroy+0x80/0xfc) from [<c0211230>] (drm_gem_object_free+0x28/0x34)
[<c0211230>] (drm_gem_object_free+0x28/0x34) from [<c0211bd0>] (drm_gem_object_release_handle+0xcc/0xd8)
[<c0211bd0>] (drm_gem_object_release_handle+0xcc/0xd8) from [<c01abe10>] (idr_for_each+0x74/0xb8)
[<c01abe10>] (idr_for_each+0x74/0xb8) from [<c02114e4>] (drm_gem_release+0x1c/0x30)
[<c02114e4>] (drm_gem_release+0x1c/0x30) from [<c0210ae8>] (drm_release+0x608/0x694)
[<c0210ae8>] (drm_release+0x608/0x694) from [<c00b75a0>] (fput+0xb8/0x228)
[<c00b75a0>] (fput+0xb8/0x228) from [<c00b40c4>] (filp_close+0x64/0x84)
[<c00b40c4>] (filp_close+0x64/0x84) from [<c0029d54>] (put_files_struct+0xe8/0x104)
[<c0029d54>] (put_files_struct+0xe8/0x104) from [<c002b930>] (do_exit+0x608/0x774)
[<c002b930>] (do_exit+0x608/0x774) from [<c002bae4>] (do_group_exit+0x48/0xb4)
[<c002bae4>] (do_group_exit+0x48/0xb4) from [<c002bb60>] (sys_exit_group+0x10/0x18)
[<c002bb60>] (sys_exit_group+0x10/0x18) from [<c000ee80>] (ret_fast_syscall+0x0/0x30)
This patch modifies the condition while freeing to match the condition
used while allocation. This fixes the above warning which arises when
array size is equal to PAGE_SIZE where allocation is done using kzalloc
but free is done using vfree.
Signed-off-by: Prathyush K <prathyush.k@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
IOMMU-aware dma_alloc_attrs() implementation allocates buffers in
power-of-two chunks to improve performance and take advantage of large
page mappings provided by some IOMMU hardware. However current code, due
to a subtle bug, allocated those chunks in the smallest-to-largest
order, what completely killed all the advantages of using larger than
page chunks. If a 4KiB chunk has been mapped as a first chunk, the
consecutive chunks are not aligned correctly to the power-of-two which
match their size and IOMMU drivers were not able to use internal
mappings of size other than the 4KiB (largest common denominator of
alignment and chunk size).
This patch fixes this issue by changing to the correct largest-to-smallest
chunk size allocation sequence.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes the following sparse warnings:
arch/arm/mm/dma-mapping.c:231:15: warning: symbol 'consistent_base' was not
declared. Should it be static?
arch/arm/mm/dma-mapping.c:326:8: warning: symbol 'coherent_pool_size' was not
declared. Should it be static?
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
CMA has been enabled unconditionally on all ARMv6+ systems to solve the
long standing issue of double kernel mappings for all dma coherent
buffers. This however created a dependency on CONFIG_EXPERIMENTAL for
the whole ARM architecture what should be really avoided. This patch
removes this dependency and lets one use old, well-tested dma-mapping
implementation also on ARMv6+ systems without the need to use
EXPERIMENTAL stuff.
Reported-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
The dma_contiguous_remap() function clears existing section maps using
the wrong size (PGDIR_SIZE instead of PMD_SIZE). This is a bug which
does not affect non-LPAE systems, where PGDIR_SIZE and PMD_SIZE are the same.
On LPAE systems, however, this bug causes the kernel to hang at this point.
This fix has been tested on both LPAE and non-LPAE kernel builds.
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
This patch adds support for CMA to dma-mapping subsystem for ARM
architecture. By default a global CMA area is used, but specific devices
are allowed to have their private memory areas if required (they can be
created with dma_declare_contiguous() function during board
initialisation).
Contiguous memory areas reserved for DMA are remapped with 2-level page
tables on boot. Once a buffer is requested, a low memory kernel mapping
is updated to to match requested memory access type.
GFP_ATOMIC allocations are performed from special pool which is created
early during boot. This way remapping page attributes is not needed on
allocation time.
CMA has been enabled unconditionally for ARMv6+ systems.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>
This patch add a complete implementation of DMA-mapping API for
devices which have IOMMU support.
This implementation tries to optimize dma address space usage by remapping
all possible physical memory chunks into a single dma address space chunk.
DMA address space is managed on top of the bitmap stored in the
dma_iommu_mapping structure stored in device->archdata. Platform setup
code has to initialize parameters of the dma address space (base address,
size, allocation precision order) with arm_iommu_create_mapping() function.
To reduce the size of the bitmap, all allocations are aligned to the
specified order of base 4 KiB pages.
dma_alloc_* functions allocate physical memory in chunks, each with
alloc_pages() function to avoid failing if the physical memory gets
fragmented. In worst case the allocated buffer is composed of 4 KiB page
chunks.
dma_map_sg() function minimizes the total number of dma address space
chunks by merging of physical memory chunks into one larger dma address
space chunk. If requested chunk (scatter list entry) boundaries
match physical page boundaries, most calls to dma_map_sg() requests will
result in creating only one chunk in dma address space.
dma_map_page() simply creates a mapping for the given page(s) in the dma
address space.
All dma functions also perform required cache operation like their
counterparts from the arm linear physical memory mapping version.
This patch contains code and fixes kindly provided by:
- Krishna Reddy <vdumpa@nvidia.com>,
- Andrzej Pietrasiewicz <andrzej.p@samsung.com>,
- Hiroshi DOYU <hdoyu@nvidia.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch converts dma_alloc/free/mmap_{coherent,writecombine}
functions to use generic alloc/free/mmap methods from dma_map_ops
structure. A new DMA_ATTR_WRITE_COMBINE DMA attribute have been
introduced to implement writecombine methods.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch just performs a global cleanup in DMA mapping implementation
for ARM architecture. Some of the tiny helper functions have been moved
to the caller code, some have been merged together.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch removes dma bounce hooks from the common dma mapping
implementation on ARM architecture and creates a separate set of
dma_map_ops for dma bounce devices.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch converts all dma_sg methods to be generic (independent of the
current DMA mapping implementation for ARM architecture). All dma sg
operations are now implemented on top of respective
dma_map_page/dma_sync_single_for* operations from dma_map_ops structure.
Before this patch there were custom methods for all scatter/gather
related operations. They iterated over the whole scatter list and called
cache related operations directly (which in turn checked if we use dma
bounce code or not and called respective version). This patch changes
them not to use such shortcut. Instead it provides similar loop over
scatter list and calls methods from the device's dma_map_ops structure.
This enables us to use device dependent implementations of cache related
operations (direct linear or dma bounce) depending on the provided
dma_map_ops structure.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch modifies dma-mapping implementation on ARM architecture to
use common dma_map_ops structure and asm-generic/dma-mapping-common.h
helpers.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
This patch removes the need for the offset parameter in dma bounce
functions. This is required to let dma-mapping framework on ARM
architecture to use common, generic dma_map_ops based dma-mapping
helpers.
Background and more detailed explaination:
dma_*_range_* functions are available from the early days of the dma
mapping api. They are the correct way of doing a partial syncs on the
buffer (usually used by the network device drivers). This patch changes
only the internal implementation of the dma bounce functions to let
them tunnel through dma_map_ops structure. The driver api stays
unchanged, so driver are obliged to call dma_*_range_* functions to
keep code clean and easy to understand.
The only drawback from this patch is reduced detection of the dma api
abuse. Let us consider the following code:
dma_addr = dma_map_single(dev, ptr, 64, DMA_TO_DEVICE);
dma_sync_single_range_for_cpu(dev, dma_addr+16, 0, 32, DMA_TO_DEVICE);
Without the patch such code fails, because dma bounce code is unable
to find the bounce buffer for the given dma_address. After the patch
the above sync call will be equivalent to:
dma_sync_single_range_for_cpu(dev, dma_addr, 16, 32, DMA_TO_DEVICE);
which succeeds.
I don't consider this as a real problem, because DMA API abuse should be
caught by debug_dma_* function family. This patch lets us to simplify
the internal low-level implementation without chaning the driver visible
API.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Replace all uses of ~0 with DMA_ERROR_CODE, what should make the code
easier to read.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Replace all calls to printk with pr_* functions family.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-By: Subash Patel <subash.ramaswamy@linaro.org>
Add a new seqfile for reporting coherent DMA allocations. This contains
the address range, size and the function which was used to allocate
each region, allowing these allocations to be viewed in much the same
way as /proc/vmallocinfo.
The DMA coherent region has limited space, so this allows allocation
failures to be viewed, as well as finding out how much space is being
used.
Make sure this file is only readable by root - same as vmallocinfo - to
prevent information leakage.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
dma_alloc_coherent wants to split pages after allocation in order to
reduce the memory footprint. This does not work well with GFP_COMP
pages, so drop this flag before allocation.
This patch is ported from arch/avr32
(commit 3611553ef9).
[swarren: s/HUGETLB_PAGE/HUGETLBFS/ in comment, minor comment cleanup]
Signed-off-by: Sumit Bhattacharya <sumitb@nvidia.com>
Tested-by: Varun Colbert <vcolbert@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Commit 99d1717d (ARM: Add init_consistent_dma_size()) introduces dynamic
allocation of the consistent_pte array. The number of PTEs should be
calculated based on the number of PMD entries rather than PGD, hence the
PMD_SHIFT.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
If the attempt to map a page for DMA fails (eg, because we're out of
mapping space) then we must not hold on to the page we allocated for
DMA - doing so will result in a memory leak.
Cc: <stable@kernel.org>
Reported-by: Bryan Phillippe <bp@darkforest.org>
Tested-by: Bryan Phillippe <bp@darkforest.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Jingoo Han