Merge tag 'dma-mapping-5.8' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - enhance the dma pool to allow atomic allocation on x86 with AMD SEV
   (David Rientjes)

 - two small cleanups (Jason Yan and Peter Collingbourne)

* tag 'dma-mapping-5.8' of git://git.infradead.org/users/hch/dma-mapping:
  dma-contiguous: fix comment for dma_release_from_contiguous
  dma-pool: scale the default DMA coherent pool size with memory capacity
  x86/mm: unencrypted non-blocking DMA allocations use coherent pools
  dma-pool: add pool sizes to debugfs
  dma-direct: atomic allocations must come from atomic coherent pools
  dma-pool: dynamically expanding atomic pools
  dma-pool: add additional coherent pools to map to gfp mask
  dma-remap: separate DMA atomic pools from direct remap code
  dma-debug: make __dma_entry_alloc_check_leak() static

arch/x86/Kconfig

@@ -1524,6 +1524,7 @@ config X86_CPA_STATISTICS
 config AMD_MEM_ENCRYPT
 	bool "AMD Secure Memory Encryption (SME) support"
 	depends on X86_64 && CPU_SUP_AMD
+	select DMA_COHERENT_POOL
 	select DYNAMIC_PHYSICAL_MASK
 	select ARCH_USE_MEMREMAP_PROT
 	select ARCH_HAS_FORCE_DMA_UNENCRYPTED

drivers/iommu/dma-iommu.c

@@ -952,7 +952,7 @@ static void __iommu_dma_free(struct device *dev, size_t size, void *cpu_addr)
 
 	/* Non-coherent atomic allocation? Easy */
 	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-	    dma_free_from_pool(cpu_addr, alloc_size))
+	    dma_free_from_pool(dev, cpu_addr, alloc_size))
 		return;
 
 	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
@@ -1035,7 +1035,8 @@ static void *iommu_dma_alloc(struct device *dev, size_t size,
 
 	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
 	    !gfpflags_allow_blocking(gfp) && !coherent)
-		cpu_addr = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp);
+		cpu_addr = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page,
+					       gfp);
 	else
 		cpu_addr = iommu_dma_alloc_pages(dev, size, &page, gfp, attrs);
 	if (!cpu_addr)

include/linux/dma-direct.h

@@ -67,6 +67,8 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size,
 }
 
 u64 dma_direct_get_required_mask(struct device *dev);
+gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
+				  u64 *phys_mask);
 void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		gfp_t gfp, unsigned long attrs);
 void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,

include/linux/dma-mapping.h

@@ -630,9 +630,9 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
 			pgprot_t prot, const void *caller);
 void dma_common_free_remap(void *cpu_addr, size_t size);
 
-bool dma_in_atomic_pool(void *start, size_t size);
-void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags);
-bool dma_free_from_pool(void *start, size_t size);
+void *dma_alloc_from_pool(struct device *dev, size_t size,
+			  struct page **ret_page, gfp_t flags);
+bool dma_free_from_pool(struct device *dev, void *start, size_t size);
 
 int
 dma_common_get_sgtable(struct device *dev, struct sg_table *sgt, void *cpu_addr,

kernel/dma/Kconfig

@@ -79,10 +79,14 @@ config DMA_REMAP
 	select DMA_NONCOHERENT_MMAP
 	bool
 
-config DMA_DIRECT_REMAP
+config DMA_COHERENT_POOL
 	bool
 	select DMA_REMAP
 
+config DMA_DIRECT_REMAP
+	bool
+	select DMA_COHERENT_POOL
+
 config DMA_CMA
 	bool "DMA Contiguous Memory Allocator"
 	depends on HAVE_DMA_CONTIGUOUS && CMA

kernel/dma/Makefile

@@ -6,4 +6,5 @@ obj-$(CONFIG_DMA_DECLARE_COHERENT)	+= coherent.o
 obj-$(CONFIG_DMA_VIRT_OPS)		+= virt.o
 obj-$(CONFIG_DMA_API_DEBUG)		+= debug.o
 obj-$(CONFIG_SWIOTLB)			+= swiotlb.o
+obj-$(CONFIG_DMA_COHERENT_POOL)		+= pool.o
 obj-$(CONFIG_DMA_REMAP)			+= remap.o

kernel/dma/contiguous.c

@@ -222,8 +222,8 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages,
  * @gfp:   Allocation flags.
  *
  * This function allocates contiguous memory buffer for specified device. It
- * first tries to use device specific contiguous memory area if available or
- * the default global one, then tries a fallback allocation of normal pages.
+ * tries to use device specific contiguous memory area if available, or the
+ * default global one.
  *
  * Note that it byapss one-page size of allocations from the global area as
  * the addresses within one page are always contiguous, so there is no need

kernel/dma/debug.c

@@ -656,7 +656,7 @@ static struct dma_debug_entry *__dma_entry_alloc(void)
 	return entry;
 }
 
-void __dma_entry_alloc_check_leak(void)
+static void __dma_entry_alloc_check_leak(void)
 {
 	u32 tmp = nr_total_entries % nr_prealloc_entries;
 

kernel/dma/direct.c

@@ -45,8 +45,8 @@ u64 dma_direct_get_required_mask(struct device *dev)
 	return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
 }
 
-static gfp_t __dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
-		u64 *phys_limit)
+gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
+				  u64 *phys_limit)
 {
 	u64 dma_limit = min_not_zero(dma_mask, dev->bus_dma_limit);
 
@@ -76,6 +76,39 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
 			min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
 }
 
+/*
+ * Decrypting memory is allowed to block, so if this device requires
+ * unencrypted memory it must come from atomic pools.
+ */
+static inline bool dma_should_alloc_from_pool(struct device *dev, gfp_t gfp,
+					      unsigned long attrs)
+{
+	if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
+		return false;
+	if (gfpflags_allow_blocking(gfp))
+		return false;
+	if (force_dma_unencrypted(dev))
+		return true;
+	if (!IS_ENABLED(CONFIG_DMA_DIRECT_REMAP))
+		return false;
+	if (dma_alloc_need_uncached(dev, attrs))
+		return true;
+	return false;
+}
+
+static inline bool dma_should_free_from_pool(struct device *dev,
+					     unsigned long attrs)
+{
+	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
+		return true;
+	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
+	    !force_dma_unencrypted(dev))
+		return false;
+	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP))
+		return true;
+	return false;
+}
+
 struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 		gfp_t gfp, unsigned long attrs)
 {
@@ -89,8 +122,8 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
 
 	/* we always manually zero the memory once we are done: */
 	gfp &= ~__GFP_ZERO;
-	gfp |= __dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
-			&phys_limit);
+	gfp |= dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
+					   &phys_limit);
 	page = dma_alloc_contiguous(dev, alloc_size, gfp);
 	if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
 		dma_free_contiguous(dev, page, alloc_size);
@@ -125,10 +158,8 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 	struct page *page;
 	void *ret;
 
-	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-	    dma_alloc_need_uncached(dev, attrs) &&
-	    !gfpflags_allow_blocking(gfp)) {
-		ret = dma_alloc_from_pool(PAGE_ALIGN(size), &page, gfp);
+	if (dma_should_alloc_from_pool(dev, gfp, attrs)) {
+		ret = dma_alloc_from_pool(dev, PAGE_ALIGN(size), &page, gfp);
 		if (!ret)
 			return NULL;
 		goto done;
@@ -204,6 +235,11 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
 {
 	unsigned int page_order = get_order(size);
 
+	/* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
+	if (dma_should_free_from_pool(dev, attrs) &&
+	    dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
+		return;
+
 	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
 	    !force_dma_unencrypted(dev)) {
 		/* cpu_addr is a struct page cookie, not a kernel address */
@@ -211,10 +247,6 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
 		return;
 	}
 
-	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
-	    dma_free_from_pool(cpu_addr, PAGE_ALIGN(size)))
-		return;
-
 	if (force_dma_unencrypted(dev))
 		set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
 

kernel/dma/pool.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2020 Google LLC
+ */
+#include <linux/debugfs.h>
+#include <linux/dma-direct.h>
+#include <linux/dma-noncoherent.h>
+#include <linux/dma-contiguous.h>
+#include <linux/init.h>
+#include <linux/genalloc.h>
+#include <linux/set_memory.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+static struct gen_pool *atomic_pool_dma __ro_after_init;
+static unsigned long pool_size_dma;
+static struct gen_pool *atomic_pool_dma32 __ro_after_init;
+static unsigned long pool_size_dma32;
+static struct gen_pool *atomic_pool_kernel __ro_after_init;
+static unsigned long pool_size_kernel;
+
+/* Size can be defined by the coherent_pool command line */
+static size_t atomic_pool_size;
+
+/* Dynamic background expansion when the atomic pool is near capacity */
+static struct work_struct atomic_pool_work;
+
+static int __init early_coherent_pool(char *p)
+{
+	atomic_pool_size = memparse(p, &p);
+	return 0;
+}
+early_param("coherent_pool", early_coherent_pool);
+
+static void __init dma_atomic_pool_debugfs_init(void)
+{
+	struct dentry *root;
+
+	root = debugfs_create_dir("dma_pools", NULL);
+	if (IS_ERR_OR_NULL(root))
+		return;
+
+	debugfs_create_ulong("pool_size_dma", 0400, root, &pool_size_dma);
+	debugfs_create_ulong("pool_size_dma32", 0400, root, &pool_size_dma32);
+	debugfs_create_ulong("pool_size_kernel", 0400, root, &pool_size_kernel);
+}
+
+static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
+{
+	if (gfp & __GFP_DMA)
+		pool_size_dma += size;
+	else if (gfp & __GFP_DMA32)
+		pool_size_dma32 += size;
+	else
+		pool_size_kernel += size;
+}
+
+static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
+			      gfp_t gfp)
+{
+	unsigned int order;
+	struct page *page;
+	void *addr;
+	int ret = -ENOMEM;
+
+	/* Cannot allocate larger than MAX_ORDER-1 */
+	order = min(get_order(pool_size), MAX_ORDER-1);
+
+	do {
+		pool_size = 1 << (PAGE_SHIFT + order);
+
+		if (dev_get_cma_area(NULL))
+			page = dma_alloc_from_contiguous(NULL, 1 << order,
+							 order, false);
+		else
+			page = alloc_pages(gfp, order);
+	} while (!page && order-- > 0);
+	if (!page)
+		goto out;
+
+	arch_dma_prep_coherent(page, pool_size);
+
+#ifdef CONFIG_DMA_DIRECT_REMAP
+	addr = dma_common_contiguous_remap(page, pool_size,
+					   pgprot_dmacoherent(PAGE_KERNEL),
+					   __builtin_return_address(0));
+	if (!addr)
+		goto free_page;
+#else
+	addr = page_to_virt(page);
+#endif
+	/*
+	 * Memory in the atomic DMA pools must be unencrypted, the pools do not
+	 * shrink so no re-encryption occurs in dma_direct_free_pages().
+	 */
+	ret = set_memory_decrypted((unsigned long)page_to_virt(page),
+				   1 << order);
+	if (ret)
+		goto remove_mapping;
+	ret = gen_pool_add_virt(pool, (unsigned long)addr, page_to_phys(page),
+				pool_size, NUMA_NO_NODE);
+	if (ret)
+		goto encrypt_mapping;
+
+	dma_atomic_pool_size_add(gfp, pool_size);
+	return 0;
+
+encrypt_mapping:
+	ret = set_memory_encrypted((unsigned long)page_to_virt(page),
+				   1 << order);
+	if (WARN_ON_ONCE(ret)) {
+		/* Decrypt succeeded but encrypt failed, purposely leak */
+		goto out;
+	}
+remove_mapping:
+#ifdef CONFIG_DMA_DIRECT_REMAP
+	dma_common_free_remap(addr, pool_size);
+#endif
+free_page: __maybe_unused
+	if (!dma_release_from_contiguous(NULL, page, 1 << order))
+		__free_pages(page, order);
+out:
+	return ret;
+}
+
+static void atomic_pool_resize(struct gen_pool *pool, gfp_t gfp)
+{
+	if (pool && gen_pool_avail(pool) < atomic_pool_size)
+		atomic_pool_expand(pool, gen_pool_size(pool), gfp);
+}
+
+static void atomic_pool_work_fn(struct work_struct *work)
+{
+	if (IS_ENABLED(CONFIG_ZONE_DMA))
+		atomic_pool_resize(atomic_pool_dma,
+				   GFP_KERNEL | GFP_DMA);
+	if (IS_ENABLED(CONFIG_ZONE_DMA32))
+		atomic_pool_resize(atomic_pool_dma32,
+				   GFP_KERNEL | GFP_DMA32);
+	atomic_pool_resize(atomic_pool_kernel, GFP_KERNEL);
+}
+
+static __init struct gen_pool *__dma_atomic_pool_init(size_t pool_size,
+						      gfp_t gfp)
+{
+	struct gen_pool *pool;
+	int ret;
+
+	pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+	if (!pool)
+		return NULL;
+
+	gen_pool_set_algo(pool, gen_pool_first_fit_order_align, NULL);
+
+	ret = atomic_pool_expand(pool, pool_size, gfp);
+	if (ret) {
+		gen_pool_destroy(pool);
+		pr_err("DMA: failed to allocate %zu KiB %pGg pool for atomic allocation\n",
+		       pool_size >> 10, &gfp);
+		return NULL;
+	}
+
+	pr_info("DMA: preallocated %zu KiB %pGg pool for atomic allocations\n",
+		gen_pool_size(pool) >> 10, &gfp);
+	return pool;
+}
+
+static int __init dma_atomic_pool_init(void)
+{
+	int ret = 0;
+
+	/*
+	 * If coherent_pool was not used on the command line, default the pool
+	 * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1.
+	 */
+	if (!atomic_pool_size) {
+		atomic_pool_size = max(totalram_pages() >> PAGE_SHIFT, 1UL) *
+					SZ_128K;
+		atomic_pool_size = min_t(size_t, atomic_pool_size,
+					 1 << (PAGE_SHIFT + MAX_ORDER-1));
+	}
+	INIT_WORK(&atomic_pool_work, atomic_pool_work_fn);
+
+	atomic_pool_kernel = __dma_atomic_pool_init(atomic_pool_size,
+						    GFP_KERNEL);
+	if (!atomic_pool_kernel)
+		ret = -ENOMEM;
+	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
+		atomic_pool_dma = __dma_atomic_pool_init(atomic_pool_size,
+						GFP_KERNEL | GFP_DMA);
+		if (!atomic_pool_dma)
+			ret = -ENOMEM;
+	}
+	if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
+		atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
+						GFP_KERNEL | GFP_DMA32);
+		if (!atomic_pool_dma32)
+			ret = -ENOMEM;
+	}
+
+	dma_atomic_pool_debugfs_init();
+	return ret;
+}
+postcore_initcall(dma_atomic_pool_init);
+
+static inline struct gen_pool *dev_to_pool(struct device *dev)
+{
+	u64 phys_mask;
+	gfp_t gfp;
+
+	gfp = dma_direct_optimal_gfp_mask(dev, dev->coherent_dma_mask,
+					  &phys_mask);
+	if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp == GFP_DMA)
+		return atomic_pool_dma;
+	if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp == GFP_DMA32)
+		return atomic_pool_dma32;
+	return atomic_pool_kernel;
+}
+
+static bool dma_in_atomic_pool(struct device *dev, void *start, size_t size)
+{
+	struct gen_pool *pool = dev_to_pool(dev);
+
+	if (unlikely(!pool))
+		return false;
+	return gen_pool_has_addr(pool, (unsigned long)start, size);
+}
+
+void *dma_alloc_from_pool(struct device *dev, size_t size,
+			  struct page **ret_page, gfp_t flags)
+{
+	struct gen_pool *pool = dev_to_pool(dev);
+	unsigned long val;
+	void *ptr = NULL;
+
+	if (!pool) {
+		WARN(1, "%pGg atomic pool not initialised!\n", &flags);
+		return NULL;
+	}
+
+	val = gen_pool_alloc(pool, size);
+	if (val) {
+		phys_addr_t phys = gen_pool_virt_to_phys(pool, val);
+
+		*ret_page = pfn_to_page(__phys_to_pfn(phys));
+		ptr = (void *)val;
+		memset(ptr, 0, size);
+	}
+	if (gen_pool_avail(pool) < atomic_pool_size)
+		schedule_work(&atomic_pool_work);
+
+	return ptr;
+}
+
+bool dma_free_from_pool(struct device *dev, void *start, size_t size)
+{
+	struct gen_pool *pool = dev_to_pool(dev);
+
+	if (!dma_in_atomic_pool(dev, start, size))
+		return false;
+	gen_pool_free(pool, (unsigned long)start, size);
+	return true;
+}

kernel/dma/remap.c

 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2012 ARM Ltd.
  * Copyright (c) 2014 The Linux Foundation
  */
-#include <linux/dma-direct.h>
-#include <linux/dma-noncoherent.h>
-#include <linux/dma-contiguous.h>
-#include <linux/init.h>
-#include <linux/genalloc.h>
+#include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 
@@ -73,117 +68,3 @@ void dma_common_free_remap(void *cpu_addr, size_t size)
 	unmap_kernel_range((unsigned long)cpu_addr, PAGE_ALIGN(size));
 	vunmap(cpu_addr);
 }
-
-#ifdef CONFIG_DMA_DIRECT_REMAP
-static struct gen_pool *atomic_pool __ro_after_init;
-
-#define DEFAULT_DMA_COHERENT_POOL_SIZE  SZ_256K
-static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE;
-
-static int __init early_coherent_pool(char *p)
-{
-	atomic_pool_size = memparse(p, &p);
-	return 0;
-}
-early_param("coherent_pool", early_coherent_pool);
-
-static gfp_t dma_atomic_pool_gfp(void)
-{
-	if (IS_ENABLED(CONFIG_ZONE_DMA))
-		return GFP_DMA;
-	if (IS_ENABLED(CONFIG_ZONE_DMA32))
-		return GFP_DMA32;
-	return GFP_KERNEL;
-}
-
-static int __init dma_atomic_pool_init(void)
-{
-	unsigned int pool_size_order = get_order(atomic_pool_size);
-	unsigned long nr_pages = atomic_pool_size >> PAGE_SHIFT;
-	struct page *page;
-	void *addr;
-	int ret;
-
-	if (dev_get_cma_area(NULL))
-		page = dma_alloc_from_contiguous(NULL, nr_pages,
-						 pool_size_order, false);
-	else
-		page = alloc_pages(dma_atomic_pool_gfp(), pool_size_order);
-	if (!page)
-		goto out;
-
-	arch_dma_prep_coherent(page, atomic_pool_size);
-
-	atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
-	if (!atomic_pool)
-		goto free_page;
-
-	addr = dma_common_contiguous_remap(page, atomic_pool_size,
-					   pgprot_dmacoherent(PAGE_KERNEL),
-					   __builtin_return_address(0));
-	if (!addr)
-		goto destroy_genpool;
-
-	ret = gen_pool_add_virt(atomic_pool, (unsigned long)addr,
-				page_to_phys(page), atomic_pool_size, -1);
-	if (ret)
-		goto remove_mapping;
-	gen_pool_set_algo(atomic_pool, gen_pool_first_fit_order_align, NULL);
-
-	pr_info("DMA: preallocated %zu KiB pool for atomic allocations\n",
-		atomic_pool_size / 1024);
-	return 0;
-
-remove_mapping:
-	dma_common_free_remap(addr, atomic_pool_size);
-destroy_genpool:
-	gen_pool_destroy(atomic_pool);
-	atomic_pool = NULL;
-free_page:
-	if (!dma_release_from_contiguous(NULL, page, nr_pages))
-		__free_pages(page, pool_size_order);
-out:
-	pr_err("DMA: failed to allocate %zu KiB pool for atomic coherent allocation\n",
-		atomic_pool_size / 1024);
-	return -ENOMEM;
-}
-postcore_initcall(dma_atomic_pool_init);
-
-bool dma_in_atomic_pool(void *start, size_t size)
-{
-	if (unlikely(!atomic_pool))
-		return false;
-
-	return gen_pool_has_addr(atomic_pool, (unsigned long)start, size);
-}
-
-void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
-{
-	unsigned long val;
-	void *ptr = NULL;
-
-	if (!atomic_pool) {
-		WARN(1, "coherent pool not initialised!\n");
-		return NULL;
-	}
-
-	val = gen_pool_alloc(atomic_pool, size);
-	if (val) {
-		phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
-
-		*ret_page = pfn_to_page(__phys_to_pfn(phys));
-		ptr = (void *)val;
-		memset(ptr, 0, size);
-	}
-
-	return ptr;
-}
-
-bool dma_free_from_pool(void *start, size_t size)
-{
-	if (!dma_in_atomic_pool(start, size))
-		return false;
-	gen_pool_free(atomic_pool, (unsigned long)start, size);
-	return true;
-}
-#endif /* CONFIG_DMA_DIRECT_REMAP */