[PATCH 1/9] mm: Provide new get_vaddr_frames() helper

[PATCH 1/9] mm: Provide new get_vaddr_frames() helper

[Mauro Carvalho Chehab]

From: Jan Kara <jack@suse.cz>

Provide new function get_vaddr_frames().  This function maps virtual
addresses from given start and fills given array with page frame numbers of
the corresponding pages. If given 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. Caller
must make sure pfns aren't reused for anything else while he is using
them.

This function is created for various drivers to simplify handling of
their buffers.

Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0755b9fd03a7..dcd1f02a78e9 100644
--- a/include/linux/mm.h
+++ b/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;
@@ -1197,6 +1198,49 @@ 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);
diff --git a/mm/gup.c b/mm/gup.c
index 6297f6bccfb1..9d7f4fde30cb 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -8,6 +8,7 @@
 #include <linux/rmap.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
+#include <linux/vmalloc.h>
 
 #include <linux/sched.h>
 #include <linux/rwsem.h>
@@ -936,6 +937,231 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
 	return ret;	/* 0 or negative error code */
 }
 
+/*
+ * 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);
+	if (!is_vmalloc_addr(vec))
+		kfree(vec);
+	else
+		vfree(vec);
+}
+EXPORT_SYMBOL(frame_vector_destroy);
+
 /**
  * get_dump_page() - pin user page in memory while writing it to core dump
  * @addr: user address
-- 
2.4.2

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Re: [PATCH 1/9] mm: Provide new get_vaddr_frames() helper

[Sergey Senozhatsky]

On (06/10/15 06:20), Mauro Carvalho Chehab wrote:
[..]
> +
> +/**
> + * 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);
> +	if (!is_vmalloc_addr(vec))
> +		kfree(vec);
> +	else
> +		vfree(vec);

minor:  kvfree(vec);

	-ss

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[PATCH 9/9] [media] mm: Move get_vaddr_frames() behind a config option

[Mauro Carvalho Chehab]

From: Jan Kara <jack@suse.cz>

get_vaddr_frames() is used by relatively rare drivers so hide it and the
related functions behind a config option that is selected only by
drivers that need the infrastructure.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

 create mode 100644 mm/frame_vector.c

diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
index 0a6780367d28..fc678289cf79 100644
--- a/drivers/gpu/drm/exynos/Kconfig
+++ b/drivers/gpu/drm/exynos/Kconfig
@@ -71,6 +71,7 @@ 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.
 
diff --git a/drivers/media/platform/omap/Kconfig b/drivers/media/platform/omap/Kconfig
index dc2aaab54aef..217d613b0fe7 100644
--- a/drivers/media/platform/omap/Kconfig
+++ b/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.
diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
index f7a01a72eb9e..f38f6e387f04 100644
--- a/drivers/media/v4l2-core/Kconfig
+++ b/drivers/media/v4l2-core/Kconfig
@@ -73,6 +73,7 @@ config VIDEOBUF2_CORE
 
 config VIDEOBUF2_MEMOPS
 	tristate
+	select FRAME_VECTOR
 
 config VIDEOBUF2_DMA_CONTIG
 	tristate
diff --git a/mm/Kconfig b/mm/Kconfig
index 390214da4546..2ca52e9986f0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -635,3 +635,6 @@ config MAX_STACK_SIZE_MB
 	  changed to a smaller value in which case that is used.
 
 	  A sane initial value is 80 MB.
+
+config FRAME_VECTOR
+	bool
diff --git a/mm/Makefile b/mm/Makefile
index 98c4eaeabdcb..be5d5c866305 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -78,3 +78,4 @@ obj-$(CONFIG_CMA)	+= cma.o
 obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
 obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
+obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
diff --git a/mm/frame_vector.c b/mm/frame_vector.c
new file mode 100644
index 000000000000..31a2bd5f41d5
--- /dev/null
+++ b/mm/frame_vector.c
@@ -0,0 +1,232 @@
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/mm.h>
+#include <linux/slab.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);
+	if (!is_vmalloc_addr(vec))
+		kfree(vec);
+	else
+		vfree(vec);
+}
+EXPORT_SYMBOL(frame_vector_destroy);
diff --git a/mm/gup.c b/mm/gup.c
index 9d7f4fde30cb..222d57e335f9 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -937,231 +937,6 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
 	return ret;	/* 0 or negative error code */
 }
 
-/*
- * 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);
-	if (!is_vmalloc_addr(vec))
-		kfree(vec);
-	else
-		vfree(vec);
-}
-EXPORT_SYMBOL(frame_vector_destroy);
-
 /**
  * get_dump_page() - pin user page in memory while writing it to core dump
  * @addr: user address
-- 
2.4.2

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Re: [PATCH 9/9] [media] mm: Move get_vaddr_frames() behind a config option

[Josh Triplett]

On Wed, Jun 10, 2015 at 06:20:52AM -0300, Mauro Carvalho Chehab wrote:
> From: Jan Kara <jack@suse.cz>
> 
> get_vaddr_frames() is used by relatively rare drivers so hide it and the
> related functions behind a config option that is selected only by
> drivers that need the infrastructure.
> 
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> 
> Signed-off-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Seems sensible to me.

Since this patch makes the kernel smaller, can you include the delta
from bloat-o-meter between allnoconfig with and without this patch?

Also, I assume you've compile-tested the kernel with allyesconfig minus
the three options that now have "select FRAME_VECTOR", to make sure it
builds?

>  create mode 100644 mm/frame_vector.c
> 
> diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
> index 0a6780367d28..fc678289cf79 100644
> --- a/drivers/gpu/drm/exynos/Kconfig
> +++ b/drivers/gpu/drm/exynos/Kconfig
> @@ -71,6 +71,7 @@ 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.
>  
> diff --git a/drivers/media/platform/omap/Kconfig b/drivers/media/platform/omap/Kconfig
> index dc2aaab54aef..217d613b0fe7 100644
> --- a/drivers/media/platform/omap/Kconfig
> +++ b/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.
> diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
> index f7a01a72eb9e..f38f6e387f04 100644
> --- a/drivers/media/v4l2-core/Kconfig
> +++ b/drivers/media/v4l2-core/Kconfig
> @@ -73,6 +73,7 @@ config VIDEOBUF2_CORE
>  
>  config VIDEOBUF2_MEMOPS
>  	tristate
> +	select FRAME_VECTOR
>  
>  config VIDEOBUF2_DMA_CONTIG
>  	tristate
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 390214da4546..2ca52e9986f0 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -635,3 +635,6 @@ config MAX_STACK_SIZE_MB
>  	  changed to a smaller value in which case that is used.
>  
>  	  A sane initial value is 80 MB.
> +
> +config FRAME_VECTOR
> +	bool
> diff --git a/mm/Makefile b/mm/Makefile
> index 98c4eaeabdcb..be5d5c866305 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -78,3 +78,4 @@ obj-$(CONFIG_CMA)	+= cma.o
>  obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
>  obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
>  obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
> +obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
> diff --git a/mm/frame_vector.c b/mm/frame_vector.c
> new file mode 100644
> index 000000000000..31a2bd5f41d5
> --- /dev/null
> +++ b/mm/frame_vector.c
> @@ -0,0 +1,232 @@
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/mm.h>
> +#include <linux/slab.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);
> +	if (!is_vmalloc_addr(vec))
> +		kfree(vec);
> +	else
> +		vfree(vec);
> +}
> +EXPORT_SYMBOL(frame_vector_destroy);
> diff --git a/mm/gup.c b/mm/gup.c
> index 9d7f4fde30cb..222d57e335f9 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -937,231 +937,6 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
>  	return ret;	/* 0 or negative error code */
>  }
>  
> -/*
> - * 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);
> -	if (!is_vmalloc_addr(vec))
> -		kfree(vec);
> -	else
> -		vfree(vec);
> -}
> -EXPORT_SYMBOL(frame_vector_destroy);
> -
>  /**
>   * get_dump_page() - pin user page in memory while writing it to core dump
>   * @addr: user address
> -- 
> 2.4.2
> 

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Re: [PATCH 9/9] [media] mm: Move get_vaddr_frames() behind a config option

[Jan Kara]

On Wed 10-06-15 09:37:20, Josh Triplett wrote:
> On Wed, Jun 10, 2015 at 06:20:52AM -0300, Mauro Carvalho Chehab wrote:
> > From: Jan Kara <jack@suse.cz>
> > 
> > get_vaddr_frames() is used by relatively rare drivers so hide it and the
> > related functions behind a config option that is selected only by
> > drivers that need the infrastructure.
> > 
> > Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> > Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> 
> Seems sensible to me.
> 
> Since this patch makes the kernel smaller, can you include the delta
> from bloat-o-meter between allnoconfig with and without this patch?

The results are:

add/remove: 0/6 grow/shrink: 0/0 up/down: 0/-868 (-868)
function                                     old     new   delta
frame_vector_destroy                          55       -     -55
frame_vector_to_pfns                          56       -     -56
frame_vector_create                           81       -     -81
put_vaddr_frames                              93       -     -93
frame_vector_to_pages                         98       -     -98
get_vaddr_frames                             485       -    -485

I've added it to the changelog of the patch.

> Also, I assume you've compile-tested the kernel with allyesconfig minus
> the three options that now have "select FRAME_VECTOR", to make sure it
> builds?
  I did not because the config option VIDEOBUF2_MEMOPS is a virtual one
selected transitively by quite a few video drivers and I didn't bother with
tracking down all of them... But since that config option guards
compilation of the code I modified I'm pretty confident I got it right.

								Honza

> >  create mode 100644 mm/frame_vector.c
> > 
> > diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
> > index 0a6780367d28..fc678289cf79 100644
> > --- a/drivers/gpu/drm/exynos/Kconfig
> > +++ b/drivers/gpu/drm/exynos/Kconfig
> > @@ -71,6 +71,7 @@ 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.
> >  
> > diff --git a/drivers/media/platform/omap/Kconfig b/drivers/media/platform/omap/Kconfig
> > index dc2aaab54aef..217d613b0fe7 100644
> > --- a/drivers/media/platform/omap/Kconfig
> > +++ b/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.
> > diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig
> > index f7a01a72eb9e..f38f6e387f04 100644
> > --- a/drivers/media/v4l2-core/Kconfig
> > +++ b/drivers/media/v4l2-core/Kconfig
> > @@ -73,6 +73,7 @@ config VIDEOBUF2_CORE
> >  
> >  config VIDEOBUF2_MEMOPS
> >  	tristate
> > +	select FRAME_VECTOR
> >  
> >  config VIDEOBUF2_DMA_CONTIG
> >  	tristate
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > index 390214da4546..2ca52e9986f0 100644
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -635,3 +635,6 @@ config MAX_STACK_SIZE_MB
> >  	  changed to a smaller value in which case that is used.
> >  
> >  	  A sane initial value is 80 MB.
> > +
> > +config FRAME_VECTOR
> > +	bool
> > diff --git a/mm/Makefile b/mm/Makefile
> > index 98c4eaeabdcb..be5d5c866305 100644
> > --- a/mm/Makefile
> > +++ b/mm/Makefile
> > @@ -78,3 +78,4 @@ obj-$(CONFIG_CMA)	+= cma.o
> >  obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
> >  obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
> >  obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o
> > +obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o
> > diff --git a/mm/frame_vector.c b/mm/frame_vector.c
> > new file mode 100644
> > index 000000000000..31a2bd5f41d5
> > --- /dev/null
> > +++ b/mm/frame_vector.c
> > @@ -0,0 +1,232 @@
> > +#include <linux/kernel.h>
> > +#include <linux/errno.h>
> > +#include <linux/err.h>
> > +#include <linux/mm.h>
> > +#include <linux/slab.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);
> > +	if (!is_vmalloc_addr(vec))
> > +		kfree(vec);
> > +	else
> > +		vfree(vec);
> > +}
> > +EXPORT_SYMBOL(frame_vector_destroy);
> > diff --git a/mm/gup.c b/mm/gup.c
> > index 9d7f4fde30cb..222d57e335f9 100644
> > --- a/mm/gup.c
> > +++ b/mm/gup.c
> > @@ -937,231 +937,6 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
> >  	return ret;	/* 0 or negative error code */
> >  }
> >  
> > -/*
> > - * 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);
> > -	if (!is_vmalloc_addr(vec))
> > -		kfree(vec);
> > -	else
> > -		vfree(vec);
> > -}
> > -EXPORT_SYMBOL(frame_vector_destroy);
> > -
> >  /**
> >   * get_dump_page() - pin user page in memory while writing it to core dump
> >   * @addr: user address
> > -- 
> > 2.4.2
> > 
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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