Merge tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull media updates from Mauro Carvalho Chehab:
 "A series of patches that move part of the code used to allocate memory
  from the media subsystem to the mm subsystem"

[ The mm parts have been acked by VM people, and the series was
  apparently in -mm for a while   - Linus ]

* tag 'media/v4.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  [media] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
  [media] media: vb2: Remove unused functions
  [media] media: vb2: Convert vb2_dc_get_userptr() to use frame vector
  [media] media: vb2: Convert vb2_vmalloc_get_userptr() to use frame vector
  [media] media: vb2: Convert vb2_dma_sg_get_userptr() to use frame vector
  [media] vb2: Provide helpers for mapping virtual addresses
  [media] media: omap_vout: Convert omap_vout_uservirt_to_phys() to use get_vaddr_pfns()
  [media] mm: Provide new get_vaddr_frames() helper
  [media] vb2: Push mmap_sem down to memops

drivers/gpu/drm/exynos/Kconfig

@@ -77,6 +77,7 @@ config DRM_EXYNOS_VIDI
 config DRM_EXYNOS_G2D
 	bool "Exynos DRM G2D"
 	depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_G2D
+	select FRAME_VECTOR
 	help
 	  Choose this option if you want to use Exynos G2D for DRM.
 

drivers/gpu/drm/exynos/exynos_drm_g2d.c

@@ -194,10 +194,8 @@ struct g2d_cmdlist_userptr {
 	dma_addr_t		dma_addr;
 	unsigned long		userptr;
 	unsigned long		size;
-	struct page		**pages;
-	unsigned int		npages;
+	struct frame_vector	*vec;
 	struct sg_table		*sgt;
-	struct vm_area_struct	*vma;
 	atomic_t		refcount;
 	bool			in_pool;
 	bool			out_of_list;
@@ -367,6 +365,7 @@ static void g2d_userptr_put_dma_addr(struct drm_device *drm_dev,
 {
 	struct g2d_cmdlist_userptr *g2d_userptr =
 					(struct g2d_cmdlist_userptr *)obj;
+	struct page **pages;
 
 	if (!obj)
 		return;
@@ -386,19 +385,21 @@ static void g2d_userptr_put_dma_addr(struct drm_device *drm_dev,
 	exynos_gem_unmap_sgt_from_dma(drm_dev, g2d_userptr->sgt,
 					DMA_BIDIRECTIONAL);
 
-	exynos_gem_put_pages_to_userptr(g2d_userptr->pages,
-					g2d_userptr->npages,
-					g2d_userptr->vma);
+	pages = frame_vector_pages(g2d_userptr->vec);
+	if (!IS_ERR(pages)) {
+		int i;
 
-	exynos_gem_put_vma(g2d_userptr->vma);
+		for (i = 0; i < frame_vector_count(g2d_userptr->vec); i++)
+			set_page_dirty_lock(pages[i]);
+	}
+	put_vaddr_frames(g2d_userptr->vec);
+	frame_vector_destroy(g2d_userptr->vec);
 
 	if (!g2d_userptr->out_of_list)
 		list_del_init(&g2d_userptr->list);
 
 	sg_free_table(g2d_userptr->sgt);
 	kfree(g2d_userptr->sgt);
-
-	drm_free_large(g2d_userptr->pages);
 	kfree(g2d_userptr);
 }
 
@@ -412,9 +413,7 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 	struct exynos_drm_g2d_private *g2d_priv = file_priv->g2d_priv;
 	struct g2d_cmdlist_userptr *g2d_userptr;
 	struct g2d_data *g2d;
-	struct page **pages;
 	struct sg_table	*sgt;
-	struct vm_area_struct *vma;
 	unsigned long start, end;
 	unsigned int npages, offset;
 	int ret;
@@ -460,65 +459,40 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 		return ERR_PTR(-ENOMEM);
 
 	atomic_set(&g2d_userptr->refcount, 1);
+	g2d_userptr->size = size;
 
 	start = userptr & PAGE_MASK;
 	offset = userptr & ~PAGE_MASK;
 	end = PAGE_ALIGN(userptr + size);
 	npages = (end - start) >> PAGE_SHIFT;
-	g2d_userptr->npages = npages;
-
-	pages = drm_calloc_large(npages, sizeof(struct page *));
-	if (!pages) {
-		DRM_ERROR("failed to allocate pages.\n");
+	g2d_userptr->vec = frame_vector_create(npages);
+	if (!g2d_userptr->vec) {
 		ret = -ENOMEM;
 		goto err_free;
 	}
 
-	down_read(&current->mm->mmap_sem);
-	vma = find_vma(current->mm, userptr);
-	if (!vma) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to get vm region.\n");
+	ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
+	if (ret != npages) {
+		DRM_ERROR("failed to get user pages from userptr.\n");
+		if (ret < 0)
+			goto err_destroy_framevec;
 		ret = -EFAULT;
-		goto err_free_pages;
+		goto err_put_framevec;
 	}
-
-	if (vma->vm_end < userptr + size) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("vma is too small.\n");
+	if (frame_vector_to_pages(g2d_userptr->vec) < 0) {
 		ret = -EFAULT;
-		goto err_free_pages;
-	}
-
-	g2d_userptr->vma = exynos_gem_get_vma(vma);
-	if (!g2d_userptr->vma) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to copy vma.\n");
-		ret = -ENOMEM;
-		goto err_free_pages;
-	}
-
-	g2d_userptr->size = size;
-
-	ret = exynos_gem_get_pages_from_userptr(start & PAGE_MASK,
-						npages, pages, vma);
-	if (ret < 0) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to get user pages from userptr.\n");
-		goto err_put_vma;
+		goto err_put_framevec;
 	}
 
-	up_read(&current->mm->mmap_sem);
-	g2d_userptr->pages = pages;
-
 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 	if (!sgt) {
 		ret = -ENOMEM;
-		goto err_free_userptr;
+		goto err_put_framevec;
 	}
 
-	ret = sg_alloc_table_from_pages(sgt, pages, npages, offset,
-					size, GFP_KERNEL);
+	ret = sg_alloc_table_from_pages(sgt,
+					frame_vector_pages(g2d_userptr->vec),
+					npages, offset, size, GFP_KERNEL);
 	if (ret < 0) {
 		DRM_ERROR("failed to get sgt from pages.\n");
 		goto err_free_sgt;
@@ -553,16 +527,11 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 err_free_sgt:
 	kfree(sgt);
 
-err_free_userptr:
-	exynos_gem_put_pages_to_userptr(g2d_userptr->pages,
-					g2d_userptr->npages,
-					g2d_userptr->vma);
-
-err_put_vma:
-	exynos_gem_put_vma(g2d_userptr->vma);
+err_put_framevec:
+	put_vaddr_frames(g2d_userptr->vec);
 
-err_free_pages:
-	drm_free_large(pages);
+err_destroy_framevec:
+	frame_vector_destroy(g2d_userptr->vec);
 
 err_free:
 	kfree(g2d_userptr);

drivers/gpu/drm/exynos/exynos_drm_gem.c

@@ -366,103 +366,6 @@ int exynos_drm_gem_get_ioctl(struct drm_device *dev, void *data,
 	return 0;
 }
 
-struct vm_area_struct *exynos_gem_get_vma(struct vm_area_struct *vma)
-{
-	struct vm_area_struct *vma_copy;
-
-	vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
-	if (!vma_copy)
-		return NULL;
-
-	if (vma->vm_ops && vma->vm_ops->open)
-		vma->vm_ops->open(vma);
-
-	if (vma->vm_file)
-		get_file(vma->vm_file);
-
-	memcpy(vma_copy, vma, sizeof(*vma));
-
-	vma_copy->vm_mm = NULL;
-	vma_copy->vm_next = NULL;
-	vma_copy->vm_prev = NULL;
-
-	return vma_copy;
-}
-
-void exynos_gem_put_vma(struct vm_area_struct *vma)
-{
-	if (!vma)
-		return;
-
-	if (vma->vm_ops && vma->vm_ops->close)
-		vma->vm_ops->close(vma);
-
-	if (vma->vm_file)
-		fput(vma->vm_file);
-
-	kfree(vma);
-}
-
-int exynos_gem_get_pages_from_userptr(unsigned long start,
-						unsigned int npages,
-						struct page **pages,
-						struct vm_area_struct *vma)
-{
-	int get_npages;
-
-	/* the memory region mmaped with VM_PFNMAP. */
-	if (vma_is_io(vma)) {
-		unsigned int i;
-
-		for (i = 0; i < npages; ++i, start += PAGE_SIZE) {
-			unsigned long pfn;
-			int ret = follow_pfn(vma, start, &pfn);
-			if (ret)
-				return ret;
-
-			pages[i] = pfn_to_page(pfn);
-		}
-
-		if (i != npages) {
-			DRM_ERROR("failed to get user_pages.\n");
-			return -EINVAL;
-		}
-
-		return 0;
-	}
-
-	get_npages = get_user_pages(current, current->mm, start,
-					npages, 1, 1, pages, NULL);
-	get_npages = max(get_npages, 0);
-	if (get_npages != npages) {
-		DRM_ERROR("failed to get user_pages.\n");
-		while (get_npages)
-			put_page(pages[--get_npages]);
-		return -EFAULT;
-	}
-
-	return 0;
-}
-
-void exynos_gem_put_pages_to_userptr(struct page **pages,
-					unsigned int npages,
-					struct vm_area_struct *vma)
-{
-	if (!vma_is_io(vma)) {
-		unsigned int i;
-
-		for (i = 0; i < npages; i++) {
-			set_page_dirty_lock(pages[i]);
-
-			/*
-			 * undo the reference we took when populating
-			 * the table.
-			 */
-			put_page(pages[i]);
-		}
-	}
-}
-
 int exynos_gem_map_sgt_with_dma(struct drm_device *drm_dev,
 				struct sg_table *sgt,
 				enum dma_data_direction dir)

drivers/media/platform/omap/Kconfig

@@ -10,6 +10,7 @@ config VIDEO_OMAP2_VOUT
 	select OMAP2_DSS if HAS_IOMEM && ARCH_OMAP2PLUS
 	select OMAP2_VRFB if ARCH_OMAP2 || ARCH_OMAP3
 	select VIDEO_OMAP2_VOUT_VRFB if VIDEO_OMAP2_VOUT && OMAP2_VRFB
+	select FRAME_VECTOR
 	default n
 	---help---
 	  V4L2 Display driver support for OMAP2/3 based boards.

drivers/media/platform/omap/omap_vout.c

@@ -195,46 +195,34 @@ static int omap_vout_try_format(struct v4l2_pix_format *pix)
 }
 
 /*
- * omap_vout_uservirt_to_phys: This inline function is used to convert user
- * space virtual address to physical address.
+ * omap_vout_get_userptr: Convert user space virtual address to physical
+ * address.
  */
-static unsigned long omap_vout_uservirt_to_phys(unsigned long virtp)
+static int omap_vout_get_userptr(struct videobuf_buffer *vb, u32 virtp,
+				 u32 *physp)
 {
-	unsigned long physp = 0;
-	struct vm_area_struct *vma;
-	struct mm_struct *mm = current->mm;
+	struct frame_vector *vec;
+	int ret;
 
 	/* For kernel direct-mapped memory, take the easy way */
-	if (virtp >= PAGE_OFFSET)
-		return virt_to_phys((void *) virtp);
-
-	down_read(&current->mm->mmap_sem);
-	vma = find_vma(mm, virtp);
-	if (vma && (vma->vm_flags & VM_IO) && vma->vm_pgoff) {
-		/* this will catch, kernel-allocated, mmaped-to-usermode
-		   addresses */
-		physp = (vma->vm_pgoff << PAGE_SHIFT) + (virtp - vma->vm_start);
-		up_read(&current->mm->mmap_sem);
-	} else {
-		/* otherwise, use get_user_pages() for general userland pages */
-		int res, nr_pages = 1;
-		struct page *pages;
+	if (virtp >= PAGE_OFFSET) {
+		*physp = virt_to_phys((void *)virtp);
+		return 0;
+	}
 
-		res = get_user_pages(current, current->mm, virtp, nr_pages, 1,
-				0, &pages, NULL);
-		up_read(&current->mm->mmap_sem);
+	vec = frame_vector_create(1);
+	if (!vec)
+		return -ENOMEM;
 
-		if (res == nr_pages) {
-			physp =  __pa(page_address(&pages[0]) +
-					(virtp & ~PAGE_MASK));
-		} else {
-			printk(KERN_WARNING VOUT_NAME
-					"get_user_pages failed\n");
-			return 0;
-		}
+	ret = get_vaddr_frames(virtp, 1, true, false, vec);
+	if (ret != 1) {
+		frame_vector_destroy(vec);
+		return -EINVAL;
 	}
+	*physp = __pfn_to_phys(frame_vector_pfns(vec)[0]);
+	vb->priv = vec;
 
-	return physp;
+	return 0;
 }
 
 /*
@@ -784,11 +772,15 @@ static int omap_vout_buffer_prepare(struct videobuf_queue *q,
 	 * address of the buffer
 	 */
 	if (V4L2_MEMORY_USERPTR == vb->memory) {
+		int ret;
+
 		if (0 == vb->baddr)
 			return -EINVAL;
 		/* Physical address */
-		vout->queued_buf_addr[vb->i] = (u8 *)
-			omap_vout_uservirt_to_phys(vb->baddr);
+		ret = omap_vout_get_userptr(vb, vb->baddr,
+				(u32 *)&vout->queued_buf_addr[vb->i]);
+		if (ret < 0)
+			return ret;
 	} else {
 		unsigned long addr, dma_addr;
 		unsigned long size;
@@ -834,12 +826,13 @@ static void omap_vout_buffer_queue(struct videobuf_queue *q,
 static void omap_vout_buffer_release(struct videobuf_queue *q,
 			    struct videobuf_buffer *vb)
 {
-	struct omap_vout_device *vout = q->priv_data;
-
 	vb->state = VIDEOBUF_NEEDS_INIT;
+	if (vb->memory == V4L2_MEMORY_USERPTR && vb->priv) {
+		struct frame_vector *vec = vb->priv;
 
-	if (V4L2_MEMORY_MMAP != vout->memory)
-		return;
+		put_vaddr_frames(vec);
+		frame_vector_destroy(vec);
+	}
 }
 
 /*

drivers/media/v4l2-core/Kconfig

@@ -84,6 +84,7 @@ config VIDEOBUF2_CORE
 
 config VIDEOBUF2_MEMOPS
 	tristate
+	select FRAME_VECTOR
 
 config VIDEOBUF2_DMA_CONTIG
 	tristate

drivers/media/v4l2-core/videobuf2-core.c

@@ -1691,9 +1691,7 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
 		ret = __qbuf_mmap(vb, b);
 		break;
 	case V4L2_MEMORY_USERPTR:
-		down_read(&current->mm->mmap_sem);
 		ret = __qbuf_userptr(vb, b);
-		up_read(&current->mm->mmap_sem);
 		break;
 	case V4L2_MEMORY_DMABUF:
 		ret = __qbuf_dmabuf(vb, b);

drivers/media/v4l2-core/videobuf2-dma-contig.c

@@ -32,15 +32,13 @@ struct vb2_dc_buf {
 	dma_addr_t			dma_addr;
 	enum dma_data_direction		dma_dir;
 	struct sg_table			*dma_sgt;
+	struct frame_vector		*vec;
 
 	/* MMAP related */
 	struct vb2_vmarea_handler	handler;
 	atomic_t			refcount;
 	struct sg_table			*sgt_base;
 
-	/* USERPTR related */
-	struct vm_area_struct		*vma;
-
 	/* DMABUF related */
 	struct dma_buf_attachment	*db_attach;
 };
@@ -49,24 +47,6 @@ struct vb2_dc_buf {
 /*        scatterlist table functions        */
 /*********************************************/
 
-
-static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
-	void (*cb)(struct page *pg))
-{
-	struct scatterlist *s;
-	unsigned int i;
-
-	for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
-		struct page *page = sg_page(s);
-		unsigned int n_pages = PAGE_ALIGN(s->offset + s->length)
-			>> PAGE_SHIFT;
-		unsigned int j;
-
-		for (j = 0; j < n_pages; ++j, ++page)
-			cb(page);
-	}
-}
-
 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
 {
 	struct scatterlist *s;
@@ -429,92 +409,12 @@ static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
 /*       callbacks for USERPTR buffers       */
 /*********************************************/
 
-static inline int vma_is_io(struct vm_area_struct *vma)
-{
-	return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
-}
-
-static int vb2_dc_get_user_pfn(unsigned long start, int n_pages,
-	struct vm_area_struct *vma, unsigned long *res)
-{
-	unsigned long pfn, start_pfn, prev_pfn;
-	unsigned int i;
-	int ret;
-
-	if (!vma_is_io(vma))
-		return -EFAULT;
-
-	ret = follow_pfn(vma, start, &pfn);
-	if (ret)
-		return ret;
-
-	start_pfn = pfn;
-	start += PAGE_SIZE;
-
-	for (i = 1; i < n_pages; ++i, start += PAGE_SIZE) {
-		prev_pfn = pfn;
-		ret = follow_pfn(vma, start, &pfn);
-
-		if (ret) {
-			pr_err("no page for address %lu\n", start);
-			return ret;
-		}
-		if (pfn != prev_pfn + 1)
-			return -EINVAL;
-	}
-
-	*res = start_pfn;
-	return 0;
-}
-
-static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
-	int n_pages, struct vm_area_struct *vma,
-	enum dma_data_direction dma_dir)
-{
-	if (vma_is_io(vma)) {
-		unsigned int i;
-
-		for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
-			unsigned long pfn;
-			int ret = follow_pfn(vma, start, &pfn);
-
-			if (!pfn_valid(pfn))
-				return -EINVAL;
-
-			if (ret) {
-				pr_err("no page for address %lu\n", start);
-				return ret;
-			}
-			pages[i] = pfn_to_page(pfn);
-		}
-	} else {
-		int n;
-
-		n = get_user_pages(current, current->mm, start & PAGE_MASK,
-			n_pages, dma_dir == DMA_FROM_DEVICE, 1, pages, NULL);
-		/* negative error means that no page was pinned */
-		n = max(n, 0);
-		if (n != n_pages) {
-			pr_err("got only %d of %d user pages\n", n, n_pages);
-			while (n)
-				put_page(pages[--n]);
-			return -EFAULT;
-		}
-	}
-
-	return 0;
-}
-
-static void vb2_dc_put_dirty_page(struct page *page)
-{
-	set_page_dirty_lock(page);
-	put_page(page);
-}
-
 static void vb2_dc_put_userptr(void *buf_priv)
 {
 	struct vb2_dc_buf *buf = buf_priv;
 	struct sg_table *sgt = buf->dma_sgt;
+	int i;
+	struct page **pages;
 
 	if (sgt) {
 		DEFINE_DMA_ATTRS(attrs);
@@ -526,13 +426,15 @@ static void vb2_dc_put_userptr(void *buf_priv)
 		 */
 		dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 				   buf->dma_dir, &attrs);
-		if (!vma_is_io(buf->vma))
-			vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
-
+		pages = frame_vector_pages(buf->vec);
+		/* sgt should exist only if vector contains pages... */
+		BUG_ON(IS_ERR(pages));
+		for (i = 0; i < frame_vector_count(buf->vec); i++)
+			set_page_dirty_lock(pages[i]);
 		sg_free_table(sgt);
 		kfree(sgt);
 	}
-	vb2_put_vma(buf->vma);
+	vb2_destroy_framevec(buf->vec);
 	kfree(buf);
 }
 
@@ -572,13 +474,10 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 {
 	struct vb2_dc_conf *conf = alloc_ctx;
 	struct vb2_dc_buf *buf;
-	unsigned long start;
-	unsigned long end;
+	struct frame_vector *vec;
 	unsigned long offset;
-	struct page **pages;
-	int n_pages;
+	int n_pages, i;
 	int ret = 0;
-	struct vm_area_struct *vma;
 	struct sg_table *sgt;
 	unsigned long contig_size;
 	unsigned long dma_align = dma_get_cache_alignment();
@@ -604,72 +503,43 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	buf->dev = conf->dev;
 	buf->dma_dir = dma_dir;
 
-	start = vaddr & PAGE_MASK;
 	offset = vaddr & ~PAGE_MASK;
-	end = PAGE_ALIGN(vaddr + size);
-	n_pages = (end - start) >> PAGE_SHIFT;
-
-	pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
-	if (!pages) {
-		ret = -ENOMEM;
-		pr_err("failed to allocate pages table\n");
+	vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE);
+	if (IS_ERR(vec)) {
+		ret = PTR_ERR(vec);
 		goto fail_buf;
 	}
+	buf->vec = vec;
+	n_pages = frame_vector_count(vec);
+	ret = frame_vector_to_pages(vec);
+	if (ret < 0) {
+		unsigned long *nums = frame_vector_pfns(vec);
 
-	/* current->mm->mmap_sem is taken by videobuf2 core */
-	vma = find_vma(current->mm, vaddr);
-	if (!vma) {
-		pr_err("no vma for address %lu\n", vaddr);
-		ret = -EFAULT;
-		goto fail_pages;
-	}
-
-	if (vma->vm_end < vaddr + size) {
-		pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
-		ret = -EFAULT;
-		goto fail_pages;
-	}
-
-	buf->vma = vb2_get_vma(vma);
-	if (!buf->vma) {
-		pr_err("failed to copy vma\n");
-		ret = -ENOMEM;
-		goto fail_pages;
-	}
-
-	/* extract page list from userspace mapping */
-	ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, dma_dir);
-	if (ret) {
-		unsigned long pfn;
-		if (vb2_dc_get_user_pfn(start, n_pages, vma, &pfn) == 0) {
-			buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, pfn);
-			buf->size = size;
-			kfree(pages);
-			return buf;
-		}
-
-		pr_err("failed to get user pages\n");
-		goto fail_vma;
+		/*
+		 * Failed to convert to pages... Check the memory is physically
+		 * contiguous and use direct mapping
+		 */
+		for (i = 1; i < n_pages; i++)
+			if (nums[i-1] + 1 != nums[i])
+				goto fail_pfnvec;
+		buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
+		goto out;
 	}
 
 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 	if (!sgt) {
 		pr_err("failed to allocate sg table\n");
 		ret = -ENOMEM;
-		goto fail_get_user_pages;
+		goto fail_pfnvec;
 	}
 
-	ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
+	ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
 		offset, size, GFP_KERNEL);
 	if (ret) {
 		pr_err("failed to initialize sg table\n");
 		goto fail_sgt;
 	}
 
-	/* pages are no longer needed */
-	kfree(pages);
-	pages = NULL;
-
 	/*
 	 * No need to sync to the device, this will happen later when the
 	 * prepare() memop is called.
@@ -691,8 +561,9 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	}
 
 	buf->dma_addr = sg_dma_address(sgt->sgl);
-	buf->size = size;
 	buf->dma_sgt = sgt;
+out:
+	buf->size = size;
 
 	return buf;
 
@@ -701,23 +572,13 @@ static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 			   buf->dma_dir, &attrs);
 
 fail_sgt_init:
-	if (!vma_is_io(buf->vma))
-		vb2_dc_sgt_foreach_page(sgt, put_page);
 	sg_free_table(sgt);
 
 fail_sgt:
 	kfree(sgt);
 
-fail_get_user_pages:
-	if (pages && !vma_is_io(buf->vma))
-		while (n_pages)
-			put_page(pages[--n_pages]);
-
-fail_vma:
-	vb2_put_vma(buf->vma);
-
-fail_pages:
-	kfree(pages); /* kfree is NULL-proof */
+fail_pfnvec:
+	vb2_destroy_framevec(vec);
 
 fail_buf:
 	kfree(buf);

drivers/media/v4l2-core/videobuf2-dma-sg.c

@@ -38,6 +38,7 @@ struct vb2_dma_sg_buf {
 	struct device			*dev;
 	void				*vaddr;
 	struct page			**pages;
+	struct frame_vector		*vec;
 	int				offset;
 	enum dma_data_direction		dma_dir;
 	struct sg_table			sg_table;
@@ -51,7 +52,6 @@ struct vb2_dma_sg_buf {
 	unsigned int			num_pages;
 	atomic_t			refcount;
 	struct vb2_vmarea_handler	handler;
-	struct vm_area_struct		*vma;
 
 	struct dma_buf_attachment	*db_attach;
 };
@@ -225,25 +225,17 @@ static void vb2_dma_sg_finish(void *buf_priv)
 	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 }
 
-static inline int vma_is_io(struct vm_area_struct *vma)
-{
-	return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
-}
-
 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 				    unsigned long size,
 				    enum dma_data_direction dma_dir)
 {
 	struct vb2_dma_sg_conf *conf = alloc_ctx;
 	struct vb2_dma_sg_buf *buf;
-	unsigned long first, last;
-	int num_pages_from_user;
-	struct vm_area_struct *vma;
 	struct sg_table *sgt;
 	DEFINE_DMA_ATTRS(attrs);
+	struct frame_vector *vec;
 
 	dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
-
 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
 	if (!buf)
 		return NULL;
@@ -254,61 +246,19 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	buf->offset = vaddr & ~PAGE_MASK;
 	buf->size = size;
 	buf->dma_sgt = &buf->sg_table;
+	vec = vb2_create_framevec(vaddr, size, buf->dma_dir == DMA_FROM_DEVICE);
+	if (IS_ERR(vec))
+		goto userptr_fail_pfnvec;
+	buf->vec = vec;
 
-	first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
-	last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
-	buf->num_pages = last - first + 1;
-
-	buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
-			     GFP_KERNEL);
-	if (!buf->pages)
-		goto userptr_fail_alloc_pages;
-
-	vma = find_vma(current->mm, vaddr);
-	if (!vma) {
-		dprintk(1, "no vma for address %lu\n", vaddr);
-		goto userptr_fail_find_vma;
-	}
-
-	if (vma->vm_end < vaddr + size) {
-		dprintk(1, "vma at %lu is too small for %lu bytes\n",
-			vaddr, size);
-		goto userptr_fail_find_vma;
-	}
-
-	buf->vma = vb2_get_vma(vma);
-	if (!buf->vma) {
-		dprintk(1, "failed to copy vma\n");
-		goto userptr_fail_find_vma;
-	}
-
-	if (vma_is_io(buf->vma)) {
-		for (num_pages_from_user = 0;
-		     num_pages_from_user < buf->num_pages;
-		     ++num_pages_from_user, vaddr += PAGE_SIZE) {
-			unsigned long pfn;
-
-			if (follow_pfn(vma, vaddr, &pfn)) {
-				dprintk(1, "no page for address %lu\n", vaddr);
-				break;
-			}
-			buf->pages[num_pages_from_user] = pfn_to_page(pfn);
-		}
-	} else
-		num_pages_from_user = get_user_pages(current, current->mm,
-					     vaddr & PAGE_MASK,
-					     buf->num_pages,
-					     buf->dma_dir == DMA_FROM_DEVICE,
-					     1, /* force */
-					     buf->pages,
-					     NULL);
-
-	if (num_pages_from_user != buf->num_pages)
-		goto userptr_fail_get_user_pages;
+	buf->pages = frame_vector_pages(vec);
+	if (IS_ERR(buf->pages))
+		goto userptr_fail_sgtable;
+	buf->num_pages = frame_vector_count(vec);
 
 	if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 			buf->num_pages, buf->offset, size, 0))
-		goto userptr_fail_alloc_table_from_pages;
+		goto userptr_fail_sgtable;
 
 	sgt = &buf->sg_table;
 	/*
@@ -324,17 +274,9 @@ static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 
 userptr_fail_map:
 	sg_free_table(&buf->sg_table);
-userptr_fail_alloc_table_from_pages:
-userptr_fail_get_user_pages:
-	dprintk(1, "get_user_pages requested/got: %d/%d]\n",
-		buf->num_pages, num_pages_from_user);
-	if (!vma_is_io(buf->vma))
-		while (--num_pages_from_user >= 0)
-			put_page(buf->pages[num_pages_from_user]);
-	vb2_put_vma(buf->vma);
-userptr_fail_find_vma:
-	kfree(buf->pages);
-userptr_fail_alloc_pages:
+userptr_fail_sgtable:
+	vb2_destroy_framevec(vec);
+userptr_fail_pfnvec:
 	kfree(buf);
 	return NULL;
 }
@@ -362,11 +304,8 @@ static void vb2_dma_sg_put_userptr(void *buf_priv)
 	while (--i >= 0) {
 		if (buf->dma_dir == DMA_FROM_DEVICE)
 			set_page_dirty_lock(buf->pages[i]);
-		if (!vma_is_io(buf->vma))
-			put_page(buf->pages[i]);
 	}
-	kfree(buf->pages);
-	vb2_put_vma(buf->vma);
+	vb2_destroy_framevec(buf->vec);
 	kfree(buf);
 }
 

drivers/media/v4l2-core/videobuf2-memops.c

@@ -23,118 +23,62 @@
 #include <media/videobuf2-memops.h>
 
 /**
- * vb2_get_vma() - acquire and lock the virtual memory area
- * @vma:	given virtual memory area
+ * vb2_create_framevec() - map virtual addresses to pfns
+ * @start:	Virtual user address where we start mapping
+ * @length:	Length of a range to map
+ * @write:	Should we map for writing into the area
  *
- * This function attempts to acquire an area mapped in the userspace for
- * the duration of a hardware operation. The area is "locked" by performing
- * the same set of operation that are done when process calls fork() and
- * memory areas are duplicated.
- *
- * Returns a copy of a virtual memory region on success or NULL.
- */
-struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma)
-{
-	struct vm_area_struct *vma_copy;
-
-	vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
-	if (vma_copy == NULL)
-		return NULL;
-
-	if (vma->vm_ops && vma->vm_ops->open)
-		vma->vm_ops->open(vma);
-
-	if (vma->vm_file)
-		get_file(vma->vm_file);
-
-	memcpy(vma_copy, vma, sizeof(*vma));
-
-	vma_copy->vm_mm = NULL;
-	vma_copy->vm_next = NULL;
-	vma_copy->vm_prev = NULL;
-
-	return vma_copy;
-}
-EXPORT_SYMBOL_GPL(vb2_get_vma);
-
-/**
- * vb2_put_userptr() - release a userspace virtual memory area
- * @vma:	virtual memory region associated with the area to be released
- *
- * This function releases the previously acquired memory area after a hardware
- * operation.
+ * This function allocates and fills in a vector with pfns corresponding to
+ * virtual address range passed in arguments. If pfns have corresponding pages,
+ * page references are also grabbed to pin pages in memory. The function
+ * returns pointer to the vector on success and error pointer in case of
+ * failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
  */
-void vb2_put_vma(struct vm_area_struct *vma)
+struct frame_vector *vb2_create_framevec(unsigned long start,
+					 unsigned long length,
+					 bool write)
 {
-	if (!vma)
-		return;
-
-	if (vma->vm_ops && vma->vm_ops->close)
-		vma->vm_ops->close(vma);
-
-	if (vma->vm_file)
-		fput(vma->vm_file);
-
-	kfree(vma);
+	int ret;
+	unsigned long first, last;
+	unsigned long nr;
+	struct frame_vector *vec;
+
+	first = start >> PAGE_SHIFT;
+	last = (start + length - 1) >> PAGE_SHIFT;
+	nr = last - first + 1;
+	vec = frame_vector_create(nr);
+	if (!vec)
+		return ERR_PTR(-ENOMEM);
+	ret = get_vaddr_frames(start, nr, write, 1, vec);
+	if (ret < 0)
+		goto out_destroy;
+	/* We accept only complete set of PFNs */
+	if (ret != nr) {
+		ret = -EFAULT;
+		goto out_release;
+	}
+	return vec;
+out_release:
+	put_vaddr_frames(vec);
+out_destroy:
+	frame_vector_destroy(vec);
+	return ERR_PTR(ret);
 }
-EXPORT_SYMBOL_GPL(vb2_put_vma);
+EXPORT_SYMBOL(vb2_create_framevec);
 
 /**
- * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
- * @vaddr:	starting virtual address of the area to be verified
- * @size:	size of the area
- * @res_paddr:	will return physical address for the given vaddr
- * @res_vma:	will return locked copy of struct vm_area for the given area
- *
- * This function will go through memory area of size @size mapped at @vaddr and
- * verify that the underlying physical pages are contiguous. If they are
- * contiguous the virtual memory area is locked and a @res_vma is filled with
- * the copy and @res_pa set to the physical address of the buffer.
+ * vb2_destroy_framevec() - release vector of mapped pfns
+ * @vec:	vector of pfns / pages to release
  *
- * Returns 0 on success.
+ * This releases references to all pages in the vector @vec (if corresponding
+ * pfns are backed by pages) and frees the passed vector.
  */
-int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
-			   struct vm_area_struct **res_vma, dma_addr_t *res_pa)
+void vb2_destroy_framevec(struct frame_vector *vec)
 {
-	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	unsigned long offset, start, end;
-	unsigned long this_pfn, prev_pfn;
-	dma_addr_t pa = 0;
-
-	start = vaddr;
-	offset = start & ~PAGE_MASK;
-	end = start + size;
-
-	vma = find_vma(mm, start);
-
-	if (vma == NULL || vma->vm_end < end)
-		return -EFAULT;
-
-	for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
-		int ret = follow_pfn(vma, start, &this_pfn);
-		if (ret)
-			return ret;
-
-		if (prev_pfn == 0)
-			pa = this_pfn << PAGE_SHIFT;
-		else if (this_pfn != prev_pfn + 1)
-			return -EFAULT;
-
-		prev_pfn = this_pfn;
-	}
-
-	/*
-	 * Memory is contiguous, lock vma and return to the caller
-	 */
-	*res_vma = vb2_get_vma(vma);
-	if (*res_vma == NULL)
-		return -ENOMEM;
-
-	*res_pa = pa + offset;
-	return 0;
+	put_vaddr_frames(vec);
+	frame_vector_destroy(vec);
 }
-EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
+EXPORT_SYMBOL(vb2_destroy_framevec);
 
 /**
  * vb2_common_vm_open() - increase refcount of the vma

drivers/media/v4l2-core/videobuf2-vmalloc.c

@@ -23,11 +23,9 @@
 
 struct vb2_vmalloc_buf {
 	void				*vaddr;
-	struct page			**pages;
-	struct vm_area_struct		*vma;
+	struct frame_vector		*vec;
 	enum dma_data_direction		dma_dir;
 	unsigned long			size;
-	unsigned int			n_pages;
 	atomic_t			refcount;
 	struct vb2_vmarea_handler	handler;
 	struct dma_buf			*dbuf;
@@ -76,10 +74,8 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 				     enum dma_data_direction dma_dir)
 {
 	struct vb2_vmalloc_buf *buf;
-	unsigned long first, last;
-	int n_pages, offset;
-	struct vm_area_struct *vma;
-	dma_addr_t physp;
+	struct frame_vector *vec;
+	int n_pages, offset, i;
 
 	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 	if (!buf)
@@ -88,51 +84,36 @@ static void *vb2_vmalloc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 	buf->dma_dir = dma_dir;
 	offset = vaddr & ~PAGE_MASK;
 	buf->size = size;
-
-
-	vma = find_vma(current->mm, vaddr);
-	if (vma && (vma->vm_flags & VM_PFNMAP) && (vma->vm_pgoff)) {
-		if (vb2_get_contig_userptr(vaddr, size, &vma, &physp))
-			goto fail_pages_array_alloc;
-		buf->vma = vma;
-		buf->vaddr = (__force void *)ioremap_nocache(physp, size);
-		if (!buf->vaddr)
-			goto fail_pages_array_alloc;
+	vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE);
+	if (IS_ERR(vec))
+		goto fail_pfnvec_create;
+	buf->vec = vec;
+	n_pages = frame_vector_count(vec);
+	if (frame_vector_to_pages(vec) < 0) {
+		unsigned long *nums = frame_vector_pfns(vec);
+
+		/*
+		 * We cannot get page pointers for these pfns. Check memory is
+		 * physically contiguous and use direct mapping.
+		 */
+		for (i = 1; i < n_pages; i++)
+			if (nums[i-1] + 1 != nums[i])
+				goto fail_map;
+		buf->vaddr = (__force void *)
+				ioremap_nocache(nums[0] << PAGE_SHIFT, size);
 	} else {
-		first = vaddr >> PAGE_SHIFT;
-		last  = (vaddr + size - 1) >> PAGE_SHIFT;
-		buf->n_pages = last - first + 1;
-		buf->pages = kzalloc(buf->n_pages * sizeof(struct page *),
-				     GFP_KERNEL);
-		if (!buf->pages)
-			goto fail_pages_array_alloc;
-
-		/* current->mm->mmap_sem is taken by videobuf2 core */
-		n_pages = get_user_pages(current, current->mm,
-					 vaddr & PAGE_MASK, buf->n_pages,
-					 dma_dir == DMA_FROM_DEVICE,
-					 1, /* force */
-					 buf->pages, NULL);
-		if (n_pages != buf->n_pages)
-			goto fail_get_user_pages;
-
-		buf->vaddr = vm_map_ram(buf->pages, buf->n_pages, -1,
+		buf->vaddr = vm_map_ram(frame_vector_pages(vec), n_pages, -1,
 					PAGE_KERNEL);
-		if (!buf->vaddr)
-			goto fail_get_user_pages;
 	}
 
+	if (!buf->vaddr)
+		goto fail_map;
 	buf->vaddr += offset;
 	return buf;
 
-fail_get_user_pages:
-	pr_debug("get_user_pages requested/got: %d/%d]\n", n_pages,
-		 buf->n_pages);
-	while (--n_pages >= 0)
-		put_page(buf->pages[n_pages]);
-	kfree(buf->pages);
-
-fail_pages_array_alloc:
+fail_map:
+	vb2_destroy_framevec(vec);
+fail_pfnvec_create:
 	kfree(buf);
 
 	return NULL;
@@ -143,20 +124,21 @@ static void vb2_vmalloc_put_userptr(void *buf_priv)
 	struct vb2_vmalloc_buf *buf = buf_priv;
 	unsigned long vaddr = (unsigned long)buf->vaddr & PAGE_MASK;
 	unsigned int i;
+	struct page **pages;
+	unsigned int n_pages;
 
-	if (buf->pages) {
+	if (!buf->vec->is_pfns) {
+		n_pages = frame_vector_count(buf->vec);
+		pages = frame_vector_pages(buf->vec);
 		if (vaddr)
-			vm_unmap_ram((void *)vaddr, buf->n_pages);
-		for (i = 0; i < buf->n_pages; ++i) {
-			if (buf->dma_dir == DMA_FROM_DEVICE)
-				set_page_dirty_lock(buf->pages[i]);
-			put_page(buf->pages[i]);
-		}
-		kfree(buf->pages);
+			vm_unmap_ram((void *)vaddr, n_pages);
+		if (buf->dma_dir == DMA_FROM_DEVICE)
+			for (i = 0; i < n_pages; i++)
+				set_page_dirty_lock(pages[i]);
 	} else {
-		vb2_put_vma(buf->vma);
 		iounmap((__force void __iomem *)buf->vaddr);
 	}
+	vb2_destroy_framevec(buf->vec);
 	kfree(buf);
 }
 

include/linux/mm.h

@@ -20,6 +20,7 @@
 #include <linux/shrinker.h>
 #include <linux/resource.h>
 #include <linux/page_ext.h>
+#include <linux/err.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -1214,6 +1215,49 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
 		    int write, int force, struct page **pages);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages);
+
+/* Container for pinned pfns / pages */
+struct frame_vector {
+	unsigned int nr_allocated;	/* Number of frames we have space for */
+	unsigned int nr_frames;	/* Number of frames stored in ptrs array */
+	bool got_ref;		/* Did we pin pages by getting page ref? */
+	bool is_pfns;		/* Does array contain pages or pfns? */
+	void *ptrs[0];		/* Array of pinned pfns / pages. Use
+				 * pfns_vector_pages() or pfns_vector_pfns()
+				 * for access */
+};
+
+struct frame_vector *frame_vector_create(unsigned int nr_frames);
+void frame_vector_destroy(struct frame_vector *vec);
+int get_vaddr_frames(unsigned long start, unsigned int nr_pfns,
+		     bool write, bool force, struct frame_vector *vec);
+void put_vaddr_frames(struct frame_vector *vec);
+int frame_vector_to_pages(struct frame_vector *vec);
+void frame_vector_to_pfns(struct frame_vector *vec);
+
+static inline unsigned int frame_vector_count(struct frame_vector *vec)
+{
+	return vec->nr_frames;
+}
+
+static inline struct page **frame_vector_pages(struct frame_vector *vec)
+{
+	if (vec->is_pfns) {
+		int err = frame_vector_to_pages(vec);
+
+		if (err)
+			return ERR_PTR(err);
+	}
+	return (struct page **)(vec->ptrs);
+}
+
+static inline unsigned long *frame_vector_pfns(struct frame_vector *vec)
+{
+	if (!vec->is_pfns)
+		frame_vector_to_pfns(vec);
+	return (unsigned long *)(vec->ptrs);
+}
+
 struct kvec;
 int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
 			struct page **pages);

include/media/videobuf2-memops.h

@@ -15,6 +15,7 @@
 #define _MEDIA_VIDEOBUF2_MEMOPS_H
 
 #include <media/videobuf2-core.h>
+#include <linux/mm.h>
 
 /**
  * struct vb2_vmarea_handler - common vma refcount tracking handler
@@ -31,11 +32,9 @@ struct vb2_vmarea_handler {
 
 extern const struct vm_operations_struct vb2_common_vm_ops;
 
-int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
-			   struct vm_area_struct **res_vma, dma_addr_t *res_pa);
-
-struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma);
-void vb2_put_vma(struct vm_area_struct *vma);
-
+struct frame_vector *vb2_create_framevec(unsigned long start,
+					 unsigned long length,
+					 bool write);
+void vb2_destroy_framevec(struct frame_vector *vec);
 
 #endif

mm/Kconfig

@@ -677,3 +677,6 @@ config ZONE_DEVICE
 	  mapping in an O_DIRECT operation, among other things.
 
 	  If FS_DAX is enabled, then say Y.
+
+config FRAME_VECTOR
+	bool

mm/Makefile

@@ -80,3 +80,4 @@ obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
 obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
 obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
+obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o

mm/frame_vector.c

+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+
+/*
+ * get_vaddr_frames() - map virtual addresses to pfns
+ * @start:	starting user address
+ * @nr_frames:	number of pages / pfns from start to map
+ * @write:	whether pages will be written to by the caller
+ * @force:	whether to force write access even if user mapping is
+ *		readonly. See description of the same argument of
+		get_user_pages().
+ * @vec:	structure which receives pages / pfns of the addresses mapped.
+ *		It should have space for at least nr_frames entries.
+ *
+ * This function maps virtual addresses from @start and fills @vec structure
+ * with page frame numbers or page pointers to corresponding pages (choice
+ * depends on the type of the vma underlying the virtual address). If @start
+ * belongs to a normal vma, the function grabs reference to each of the pages
+ * to pin them in memory. If @start belongs to VM_IO | VM_PFNMAP vma, we don't
+ * touch page structures and the caller must make sure pfns aren't reused for
+ * anything else while he is using them.
+ *
+ * The function returns number of pages mapped which may be less than
+ * @nr_frames. In particular we stop mapping if there are more vmas of
+ * different type underlying the specified range of virtual addresses.
+ * When the function isn't able to map a single page, it returns error.
+ *
+ * This function takes care of grabbing mmap_sem as necessary.
+ */
+int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
+		     bool write, bool force, struct frame_vector *vec)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	int ret = 0;
+	int err;
+	int locked;
+
+	if (nr_frames == 0)
+		return 0;
+
+	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
+		nr_frames = vec->nr_allocated;
+
+	down_read(&mm->mmap_sem);
+	locked = 1;
+	vma = find_vma_intersection(mm, start, start + 1);
+	if (!vma) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
+		vec->got_ref = true;
+		vec->is_pfns = false;
+		ret = get_user_pages_locked(current, mm, start, nr_frames,
+			write, force, (struct page **)(vec->ptrs), &locked);
+		goto out;
+	}
+
+	vec->got_ref = false;
+	vec->is_pfns = true;
+	do {
+		unsigned long *nums = frame_vector_pfns(vec);
+
+		while (ret < nr_frames && start + PAGE_SIZE <= vma->vm_end) {
+			err = follow_pfn(vma, start, &nums[ret]);
+			if (err) {
+				if (ret == 0)
+					ret = err;
+				goto out;
+			}
+			start += PAGE_SIZE;
+			ret++;
+		}
+		/*
+		 * We stop if we have enough pages or if VMA doesn't completely
+		 * cover the tail page.
+		 */
+		if (ret >= nr_frames || start < vma->vm_end)
+			break;
+		vma = find_vma_intersection(mm, start, start + 1);
+	} while (vma && vma->vm_flags & (VM_IO | VM_PFNMAP));
+out:
+	if (locked)
+		up_read(&mm->mmap_sem);
+	if (!ret)
+		ret = -EFAULT;
+	if (ret > 0)
+		vec->nr_frames = ret;
+	return ret;
+}
+EXPORT_SYMBOL(get_vaddr_frames);
+
+/**
+ * put_vaddr_frames() - drop references to pages if get_vaddr_frames() acquired
+ *			them
+ * @vec:	frame vector to put
+ *
+ * Drop references to pages if get_vaddr_frames() acquired them. We also
+ * invalidate the frame vector so that it is prepared for the next call into
+ * get_vaddr_frames().
+ */
+void put_vaddr_frames(struct frame_vector *vec)
+{
+	int i;
+	struct page **pages;
+
+	if (!vec->got_ref)
+		goto out;
+	pages = frame_vector_pages(vec);
+	/*
+	 * frame_vector_pages() might needed to do a conversion when
+	 * get_vaddr_frames() got pages but vec was later converted to pfns.
+	 * But it shouldn't really fail to convert pfns back...
+	 */
+	if (WARN_ON(IS_ERR(pages)))
+		goto out;
+	for (i = 0; i < vec->nr_frames; i++)
+		put_page(pages[i]);
+	vec->got_ref = false;
+out:
+	vec->nr_frames = 0;
+}
+EXPORT_SYMBOL(put_vaddr_frames);
+
+/**
+ * frame_vector_to_pages - convert frame vector to contain page pointers
+ * @vec:	frame vector to convert
+ *
+ * Convert @vec to contain array of page pointers.  If the conversion is
+ * successful, return 0. Otherwise return an error. Note that we do not grab
+ * page references for the page structures.
+ */
+int frame_vector_to_pages(struct frame_vector *vec)
+{
+	int i;
+	unsigned long *nums;
+	struct page **pages;
+
+	if (!vec->is_pfns)
+		return 0;
+	nums = frame_vector_pfns(vec);
+	for (i = 0; i < vec->nr_frames; i++)
+		if (!pfn_valid(nums[i]))
+			return -EINVAL;
+	pages = (struct page **)nums;
+	for (i = 0; i < vec->nr_frames; i++)
+		pages[i] = pfn_to_page(nums[i]);
+	vec->is_pfns = false;
+	return 0;
+}
+EXPORT_SYMBOL(frame_vector_to_pages);
+
+/**
+ * frame_vector_to_pfns - convert frame vector to contain pfns
+ * @vec:	frame vector to convert
+ *
+ * Convert @vec to contain array of pfns.
+ */
+void frame_vector_to_pfns(struct frame_vector *vec)
+{
+	int i;
+	unsigned long *nums;
+	struct page **pages;
+
+	if (vec->is_pfns)
+		return;
+	pages = (struct page **)(vec->ptrs);
+	nums = (unsigned long *)pages;
+	for (i = 0; i < vec->nr_frames; i++)
+		nums[i] = page_to_pfn(pages[i]);
+	vec->is_pfns = true;
+}
+EXPORT_SYMBOL(frame_vector_to_pfns);
+
+/**
+ * frame_vector_create() - allocate & initialize structure for pinned pfns
+ * @nr_frames:	number of pfns slots we should reserve
+ *
+ * Allocate and initialize struct pinned_pfns to be able to hold @nr_pfns
+ * pfns.
+ */
+struct frame_vector *frame_vector_create(unsigned int nr_frames)
+{
+	struct frame_vector *vec;
+	int size = sizeof(struct frame_vector) + sizeof(void *) * nr_frames;
+
+	if (WARN_ON_ONCE(nr_frames == 0))
+		return NULL;
+	/*
+	 * This is absurdly high. It's here just to avoid strange effects when
+	 * arithmetics overflows.
+	 */
+	if (WARN_ON_ONCE(nr_frames > INT_MAX / sizeof(void *) / 2))
+		return NULL;
+	/*
+	 * Avoid higher order allocations, use vmalloc instead. It should
+	 * be rare anyway.
+	 */
+	if (size <= PAGE_SIZE)
+		vec = kmalloc(size, GFP_KERNEL);
+	else
+		vec = vmalloc(size);
+	if (!vec)
+		return NULL;
+	vec->nr_allocated = nr_frames;
+	vec->nr_frames = 0;
+	return vec;
+}
+EXPORT_SYMBOL(frame_vector_create);
+
+/**
+ * frame_vector_destroy() - free memory allocated to carry frame vector
+ * @vec:	Frame vector to free
+ *
+ * Free structure allocated by frame_vector_create() to carry frames.
+ */
+void frame_vector_destroy(struct frame_vector *vec)
+{
+	/* Make sure put_vaddr_frames() got called properly... */
+	VM_BUG_ON(vec->nr_frames > 0);
+	kvfree(vec);
+}
+EXPORT_SYMBOL(frame_vector_destroy);