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

From: [email-masked] (Josh Triplett)
Date: Wed, 10 Jun 2015 09:37:20 -0700

On Wed, Jun 10, 2015 at 06:20:52AM -0300, Mauro Carvalho Chehab wrote:
> From: Jan Kara <[email-masked]>
> 
> 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 <[email-masked]>
> 
> Signed-off-by: Jan Kara <[email-masked]>
> Signed-off-by: Hans Verkuil <[email-masked]>
> Signed-off-by: Mauro Carvalho Chehab <[email-masked]>

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
>