[PATCH 1/2] rename alloc_pages_exact()

[PATCH 1/2] rename alloc_pages_exact()

[Dave Hansen]

alloc_pages_exact() returns a virtual address.  But, alloc_pages() returns
a 'struct page *'.  That makes for very confused kernel hackers.

__get_free_pages(), on the other hand, returns virtual addresses.  That
makes alloc_pages_exact() a much closer match to __get_free_pages(), so
rename it to get_free_pages_exact().

Note that alloc_pages_exact()'s partner, free_pages_exact() already
matches free_pages(), so we do not have to touch the free side of things.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
---

 linux-2.6.git-dave/drivers/video/fsl-diu-fb.c  |    2 +-
 linux-2.6.git-dave/drivers/video/mxsfb.c       |    2 +-
 linux-2.6.git-dave/drivers/video/pxafb.c       |    4 ++--
 linux-2.6.git-dave/drivers/virtio/virtio_pci.c |    2 +-
 linux-2.6.git-dave/include/linux/gfp.h         |    2 +-
 linux-2.6.git-dave/kernel/profile.c            |    2 +-
 linux-2.6.git-dave/mm/page_alloc.c             |   24 ++++++++++++------------
 linux-2.6.git-dave/mm/page_cgroup.c            |    2 +-
 8 files changed, 20 insertions(+), 20 deletions(-)

diff -puN drivers/video/fsl-diu-fb.c~change-alloc_pages_exact-name drivers/video/fsl-diu-fb.c
--- linux-2.6.git/drivers/video/fsl-diu-fb.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.074400957 -0700
+++ linux-2.6.git-dave/drivers/video/fsl-diu-fb.c	2011-04-07 08:37:58.186400949 -0700
@@ -294,7 +294,7 @@ static void *fsl_diu_alloc(size_t size, 
 
 	pr_debug("size=%zu\n", size);
 
-	virt = alloc_pages_exact(size, GFP_DMA | __GFP_ZERO);
+	virt = get_free_pages_exact(GFP_DMA | __GFP_ZERO, size);
 	if (virt) {
 		*phys = virt_to_phys(virt);
 		pr_debug("virt=%p phys=%llx\n", virt,
diff -puN drivers/video/pxafb.c~change-alloc_pages_exact-name drivers/video/pxafb.c
--- linux-2.6.git/drivers/video/pxafb.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.078400957 -0700
+++ linux-2.6.git-dave/drivers/video/pxafb.c	2011-04-07 08:39:16.198395385 -0700
@@ -905,7 +905,7 @@ static int __devinit pxafb_overlay_map_v
 	/* We assume that user will use at most video_mem_size for overlay fb,
 	 * anyway, it's useless to use 16bpp main plane and 24bpp overlay
 	 */
-	ofb->video_mem = alloc_pages_exact(PAGE_ALIGN(pxafb->video_mem_size),
+	ofb->video_mem = get_free_pages_exact(PAGE_ALIGN(pxafb->video_mem_size),
 		GFP_KERNEL | __GFP_ZERO);
 	if (ofb->video_mem == NULL)
 		return -ENOMEM;
@@ -1714,7 +1714,7 @@ static int __devinit pxafb_init_video_me
 {
 	int size = PAGE_ALIGN(fbi->video_mem_size);
 
-	fbi->video_mem = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+	fbi->video_mem = get_free_pages_exact(GFP_KERNEL | __GFP_ZERO, size);
 	if (fbi->video_mem == NULL)
 		return -ENOMEM;
 
diff -puN drivers/virtio/virtio_pci.c~change-alloc_pages_exact-name drivers/virtio/virtio_pci.c
--- linux-2.6.git/drivers/virtio/virtio_pci.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.082400957 -0700
+++ linux-2.6.git-dave/drivers/virtio/virtio_pci.c	2011-04-07 08:37:58.190400949 -0700
@@ -385,7 +385,7 @@ static struct virtqueue *setup_vq(struct
 	info->msix_vector = msix_vec;
 
 	size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
-	info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
+	info->queue = get_free_pages_exact(GFP_KERNEL|__GFP_ZERO, size);
 	if (info->queue == NULL) {
 		err = -ENOMEM;
 		goto out_info;
diff -puN include/linux/gfp.h~change-alloc_pages_exact-name include/linux/gfp.h
--- linux-2.6.git/include/linux/gfp.h~change-alloc_pages_exact-name	2011-04-07 08:37:58.086400956 -0700
+++ linux-2.6.git-dave/include/linux/gfp.h	2011-04-07 08:37:58.190400949 -0700
@@ -351,7 +351,7 @@ extern struct page *alloc_pages_vma(gfp_
 extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
 extern unsigned long get_zeroed_page(gfp_t gfp_mask);
 
-void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
+void *get_free_pages_exact(gfp_t gfp_mask, size_t size);
 void free_pages_exact(void *virt, size_t size);
 
 #define __get_free_page(gfp_mask) \
diff -puN kernel/profile.c~change-alloc_pages_exact-name kernel/profile.c
--- linux-2.6.git/kernel/profile.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.090400955 -0700
+++ linux-2.6.git-dave/kernel/profile.c	2011-04-07 08:37:58.190400949 -0700
@@ -121,7 +121,7 @@ int __ref profile_init(void)
 	if (prof_buffer)
 		return 0;
 
-	prof_buffer = alloc_pages_exact(buffer_bytes,
+	prof_buffer = get_free_pages_exact(buffer_bytes,
 					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
 	if (prof_buffer)
 		return 0;
diff -puN mm/page_alloc.c~change-alloc_pages_exact-name mm/page_alloc.c
--- linux-2.6.git/mm/page_alloc.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.094400955 -0700
+++ linux-2.6.git-dave/mm/page_alloc.c	2011-04-07 08:37:58.194400949 -0700
@@ -2318,19 +2318,19 @@ void free_pages(unsigned long addr, unsi
 EXPORT_SYMBOL(free_pages);
 
 /**
- * alloc_pages_exact - allocate an exact number physically-contiguous pages.
- * @size: the number of bytes to allocate
+ * get_free_pages_exact - allocate an exact number physically-contiguous pages.
  * @gfp_mask: GFP flags for the allocation
+ * @size: the number of bytes to allocate
  *
- * This function is similar to alloc_pages(), except that it allocates the
- * minimum number of pages to satisfy the request.  alloc_pages() can only
+ * This function is similar to __get_free_pages(), except that it allocates the
+ * minimum number of pages to satisfy the request.  get_free_pages() can only
  * allocate memory in power-of-two pages.
  *
  * This function is also limited by MAX_ORDER.
  *
  * Memory allocated by this function must be released by free_pages_exact().
  */
-void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
+void *get_free_pages_exact(gfp_t gfp_mask, size_t size)
 {
 	unsigned int order = get_order(size);
 	unsigned long addr;
@@ -2349,14 +2349,14 @@ void *alloc_pages_exact(size_t size, gfp
 
 	return (void *)addr;
 }
-EXPORT_SYMBOL(alloc_pages_exact);
+EXPORT_SYMBOL(get_free_pages_exact);
 
 /**
- * free_pages_exact - release memory allocated via alloc_pages_exact()
- * @virt: the value returned by alloc_pages_exact.
- * @size: size of allocation, same value as passed to alloc_pages_exact().
+ * free_pages_exact - release memory allocated via get_free_pages_exact()
+ * @virt: the value returned by get_free_pages_exact().
+ * @size: size of allocation, same value as passed to get_free_pages_exact().
  *
- * Release the memory allocated by a previous call to alloc_pages_exact.
+ * Release the memory allocated by a previous call to get_free_pages_exact().
  */
 void free_pages_exact(void *virt, size_t size)
 {
@@ -5308,10 +5308,10 @@ void *__init alloc_large_system_hash(con
 			/*
 			 * If bucketsize is not a power-of-two, we may free
 			 * some pages at the end of hash table which
-			 * alloc_pages_exact() automatically does
+			 * get_free_pages_exact() automatically does
 			 */
 			if (get_order(size) < MAX_ORDER) {
-				table = alloc_pages_exact(size, GFP_ATOMIC);
+				table = get_free_pages_exact(GFP_ATOMIC, size);
 				kmemleak_alloc(table, size, 1, GFP_ATOMIC);
 			}
 		}
diff -puN mm/page_cgroup.c~change-alloc_pages_exact-name mm/page_cgroup.c
--- linux-2.6.git/mm/page_cgroup.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.098400955 -0700
+++ linux-2.6.git-dave/mm/page_cgroup.c	2011-04-07 08:37:58.198400948 -0700
@@ -134,7 +134,7 @@ static void *__init_refok alloc_page_cgr
 {
 	void *addr = NULL;
 
-	addr = alloc_pages_exact(size, GFP_KERNEL | __GFP_NOWARN);
+	addr = get_free_pages_exact(GFP_KERNEL | __GFP_NOWARN, size);
 	if (addr)
 		return addr;
 
diff -puN drivers/video/mxsfb.c~change-alloc_pages_exact-name drivers/video/mxsfb.c
--- linux-2.6.git/drivers/video/mxsfb.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.102400955 -0700
+++ linux-2.6.git-dave/drivers/video/mxsfb.c	2011-04-07 08:37:58.198400948 -0700
@@ -718,7 +718,7 @@ static int __devinit mxsfb_init_fbinfo(s
 	} else {
 		if (!fb_size)
 			fb_size = SZ_2M; /* default */
-		fb_virt = alloc_pages_exact(fb_size, GFP_DMA);
+		fb_virt = get_free_pages_exact(GFP_DMA, fb_size);
 		if (!fb_virt)
 			return -ENOMEM;
 
_

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[PATCH 2/2] make new alloc_pages_exact()

[Dave Hansen]

What I really wanted in the end was a highmem-capable alloc_pages_exact(),
so here it is.

It's a bit unfortunate that we have __free_pages_exact() and
free_pages_exact(), but that mess already exists with __free_pages()
vs. free_pages_exact().  So, at worst, this mirrors the mess that we
already have.

I'm also a bit worried that I've not put in something named
alloc_pages_exact(), but that behaves differently than it did before this
set.  I got all of the in-tree cases, but I'm a bit worried about
stragglers elsewhere.  So, I'm calling this __alloc_pages_exact() for
the moment.  We can take out the __ some day if it bothers people.

Note that the __get_free_pages() has a !GFP_HIGHMEM check.  Now that
we are using alloc_pages_exact() instead of __get_free_pages() for
get_free_pages_exact(), we had to add a new check in
get_free_pages_exact().

This has been compile and boot tested, and I checked that

	echo 2 > /sys/kernel/profiling

still works, since it uses get_free_pages_exact().

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
---

 linux-2.6.git-dave/drivers/video/pxafb.c |    4 -
 linux-2.6.git-dave/include/linux/gfp.h   |    4 +
 linux-2.6.git-dave/kernel/profile.c      |    4 -
 linux-2.6.git-dave/mm/page_alloc.c       |   81 +++++++++++++++++++++++--------
 4 files changed, 69 insertions(+), 24 deletions(-)

diff -puN include/linux/gfp.h~make_new_alloc_pages_exact include/linux/gfp.h
--- linux-2.6.git/include/linux/gfp.h~make_new_alloc_pages_exact	2011-04-07 08:41:08.158387017 -0700
+++ linux-2.6.git-dave/include/linux/gfp.h	2011-04-07 08:41:08.174387016 -0700
@@ -351,6 +351,10 @@ extern struct page *alloc_pages_vma(gfp_
 extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
 extern unsigned long get_zeroed_page(gfp_t gfp_mask);
 
+/* 'struct page' version */
+struct page *__alloc_pages_exact(gfp_t, size_t);
+void __free_pages_exact(struct page *, size_t);
+/* virtual address version */
 void *get_free_pages_exact(gfp_t gfp_mask, size_t size);
 void free_pages_exact(void *virt, size_t size);
 
diff -puN mm/page_alloc.c~make_new_alloc_pages_exact mm/page_alloc.c
--- linux-2.6.git/mm/page_alloc.c~make_new_alloc_pages_exact	2011-04-07 08:41:08.162387016 -0700
+++ linux-2.6.git-dave/mm/page_alloc.c	2011-04-07 09:44:33.937537711 -0700
@@ -2318,36 +2318,83 @@ void free_pages(unsigned long addr, unsi
 EXPORT_SYMBOL(free_pages);
 
 /**
- * get_free_pages_exact - allocate an exact number physically-contiguous pages.
+ * __alloc_pages_exact - allocate an exact number physically-contiguous pages.
  * @gfp_mask: GFP flags for the allocation
  * @size: the number of bytes to allocate
+ * returns: struct page for allocated memory
  *
- * This function is similar to __get_free_pages(), except that it allocates the
- * minimum number of pages to satisfy the request.  get_free_pages() can only
+ * This function is similar to alloc_pages(), except that it allocates the
+ * minimum number of pages to satisfy the request.  alloc_pages() can only
  * allocate memory in power-of-two pages.
  *
  * This function is also limited by MAX_ORDER.
  *
  * Memory allocated by this function must be released by free_pages_exact().
  */
-void *get_free_pages_exact(gfp_t gfp_mask, size_t size)
+struct page *__alloc_pages_exact(gfp_t gfp_mask, size_t size)
 {
 	unsigned int order = get_order(size);
-	unsigned long addr;
+	struct page *page;
 
-	addr = __get_free_pages(gfp_mask, order);
-	if (addr) {
-		unsigned long alloc_end = addr + (PAGE_SIZE << order);
-		unsigned long used = addr + PAGE_ALIGN(size);
+	page = alloc_pages(gfp_mask, order);
+	if (page) {
+		struct page *alloc_end = page + (1 << order);
+		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
 
-		split_page(virt_to_page((void *)addr), order);
+		split_page(page, order);
 		while (used < alloc_end) {
-			free_page(used);
-			used += PAGE_SIZE;
+			__free_page(used);
+			used++;
 		}
 	}
 
-	return (void *)addr;
+	return page;
+}
+EXPORT_SYMBOL(__alloc_pages_exact);
+
+/**
+ * __free_pages_exact - release memory allocated via __alloc_pages_exact()
+ * @virt: the value returned by alloc_pages_exact().
+ * @size: size of allocation, same value as passed to __alloc_pages_exact().
+ *
+ * Release the memory allocated by a previous call to __alloc_pages_exact().
+ */
+void __free_pages_exact(struct page *page, size_t size)
+{
+	struct page *end = page + PAGE_ALIGN(size)/PAGE_SIZE;
+
+	while (page < end) {
+		__free_page(page);
+		page++;
+	}
+}
+EXPORT_SYMBOL(__free_pages_exact);
+
+/**
+ * get_free_pages_exact - allocate an exact number physically-contiguous pages.
+ * @gfp_mask: GFP flags for the allocation
+ * @size: the number of bytes to allocate
+ * returns: virtual address of allocated memory
+ *
+ * This function is similar to __get_free_pages(), except that it allocates the
+ * minimum number of pages to satisfy the request.  get_free_pages() can only
+ * allocate memory in power-of-two pages.
+ *
+ * This function is also limited by MAX_ORDER.
+ *
+ * Memory allocated by this function must be released by free_pages_exact().
+ */
+void *get_free_pages_exact(gfp_t gfp_mask, size_t size)
+{
+	struct page *page;
+
+	/* If we are using page_address(), we can not allow highmem */
+	VM_BUG_ON((gfp_mask & __GFP_HIGHMEM) != 0);
+
+	page = __alloc_pages_exact(gfp_mask, size);
+	if (page)
+		return (void *) page_address(page);
+	return NULL;
 }
 EXPORT_SYMBOL(get_free_pages_exact);
 
@@ -2360,13 +2407,7 @@ EXPORT_SYMBOL(get_free_pages_exact);
  */
 void free_pages_exact(void *virt, size_t size)
 {
-	unsigned long addr = (unsigned long)virt;
-	unsigned long end = addr + PAGE_ALIGN(size);
-
-	while (addr < end) {
-		free_page(addr);
-		addr += PAGE_SIZE;
-	}
+	__free_pages_exact(virt_to_page(virt), size);
 }
 EXPORT_SYMBOL(free_pages_exact);
 
diff -puN kernel/profile.c~make_new_alloc_pages_exact kernel/profile.c
--- linux-2.6.git/kernel/profile.c~make_new_alloc_pages_exact	2011-04-07 08:41:08.166387016 -0700
+++ linux-2.6.git-dave/kernel/profile.c	2011-04-07 09:42:16.393582339 -0700
@@ -121,8 +121,8 @@ int __ref profile_init(void)
 	if (prof_buffer)
 		return 0;
 
-	prof_buffer = get_free_pages_exact(buffer_bytes,
-					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
+	prof_buffer = get_free_pages_exact(GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN,
+						buffer_bytes);
 	if (prof_buffer)
 		return 0;
 
diff -puN mm/swapfile.c~make_new_alloc_pages_exact mm/swapfile.c
diff -L git -puN /dev/null /dev/null
diff -puN include/linux/page-flags.h~make_new_alloc_pages_exact include/linux/page-flags.h
diff -puN drivers/video/pxafb.c~make_new_alloc_pages_exact drivers/video/pxafb.c
--- linux-2.6.git/drivers/video/pxafb.c~make_new_alloc_pages_exact	2011-04-07 09:42:40.805576050 -0700
+++ linux-2.6.git-dave/drivers/video/pxafb.c	2011-04-07 09:44:02.357555082 -0700
@@ -905,8 +905,8 @@ static int __devinit pxafb_overlay_map_v
 	/* We assume that user will use at most video_mem_size for overlay fb,
 	 * anyway, it's useless to use 16bpp main plane and 24bpp overlay
 	 */
-	ofb->video_mem = get_free_pages_exact(PAGE_ALIGN(pxafb->video_mem_size),
-		GFP_KERNEL | __GFP_ZERO);
+	ofb->video_mem = get_free_pages_exact(GFP_KERNEL | __GFP_ZERO,
+				PAGE_ALIGN(pxafb->video_mem_size));
 	if (ofb->video_mem == NULL)
 		return -ENOMEM;
 
_

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Re: [PATCH 1/2] rename alloc_pages_exact()

[David Rientjes]

On Thu, 7 Apr 2011, Dave Hansen wrote:

> 
> alloc_pages_exact() returns a virtual address.  But, alloc_pages() returns
> a 'struct page *'.  That makes for very confused kernel hackers.
> 
> __get_free_pages(), on the other hand, returns virtual addresses.  That
> makes alloc_pages_exact() a much closer match to __get_free_pages(), so
> rename it to get_free_pages_exact().
> 

The patch also reverses the arguments of the function in 
include/linux/gfp.h, undoubtedly to resemble the (mask, order) appearance 
of __get_free_pages():

	-void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
	+void *get_free_pages_exact(gfp_t gfp_mask, size_t size);

> Note that alloc_pages_exact()'s partner, free_pages_exact() already
> matches free_pages(), so we do not have to touch the free side of things.
> 
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
> Acked-by: Andi Kleen <ak@linux.intel.com>
> ---
> 
>  linux-2.6.git-dave/drivers/video/fsl-diu-fb.c  |    2 +-
>  linux-2.6.git-dave/drivers/video/mxsfb.c       |    2 +-
>  linux-2.6.git-dave/drivers/video/pxafb.c       |    4 ++--
>  linux-2.6.git-dave/drivers/virtio/virtio_pci.c |    2 +-
>  linux-2.6.git-dave/include/linux/gfp.h         |    2 +-
>  linux-2.6.git-dave/kernel/profile.c            |    2 +-
>  linux-2.6.git-dave/mm/page_alloc.c             |   24 ++++++++++++------------
>  linux-2.6.git-dave/mm/page_cgroup.c            |    2 +-
>  8 files changed, 20 insertions(+), 20 deletions(-)
> 
> diff -puN drivers/video/fsl-diu-fb.c~change-alloc_pages_exact-name drivers/video/fsl-diu-fb.c
> --- linux-2.6.git/drivers/video/fsl-diu-fb.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.074400957 -0700
> +++ linux-2.6.git-dave/drivers/video/fsl-diu-fb.c	2011-04-07 08:37:58.186400949 -0700
> @@ -294,7 +294,7 @@ static void *fsl_diu_alloc(size_t size, 
>  
>  	pr_debug("size=%zu\n", size);
>  
> -	virt = alloc_pages_exact(size, GFP_DMA | __GFP_ZERO);
> +	virt = get_free_pages_exact(GFP_DMA | __GFP_ZERO, size);
>  	if (virt) {
>  		*phys = virt_to_phys(virt);
>  		pr_debug("virt=%p phys=%llx\n", virt,
> diff -puN drivers/video/pxafb.c~change-alloc_pages_exact-name drivers/video/pxafb.c
> --- linux-2.6.git/drivers/video/pxafb.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.078400957 -0700
> +++ linux-2.6.git-dave/drivers/video/pxafb.c	2011-04-07 08:39:16.198395385 -0700
> @@ -905,7 +905,7 @@ static int __devinit pxafb_overlay_map_v
>  	/* We assume that user will use at most video_mem_size for overlay fb,
>  	 * anyway, it's useless to use 16bpp main plane and 24bpp overlay
>  	 */
> -	ofb->video_mem = alloc_pages_exact(PAGE_ALIGN(pxafb->video_mem_size),
> +	ofb->video_mem = get_free_pages_exact(PAGE_ALIGN(pxafb->video_mem_size),
>  		GFP_KERNEL | __GFP_ZERO);
>  	if (ofb->video_mem == NULL)
>  		return -ENOMEM;

Doesn't look like this is using the arguments in the newly changed order.

> @@ -1714,7 +1714,7 @@ static int __devinit pxafb_init_video_me
>  {
>  	int size = PAGE_ALIGN(fbi->video_mem_size);
>  
> -	fbi->video_mem = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
> +	fbi->video_mem = get_free_pages_exact(GFP_KERNEL | __GFP_ZERO, size);
>  	if (fbi->video_mem == NULL)
>  		return -ENOMEM;
>  
> diff -puN drivers/virtio/virtio_pci.c~change-alloc_pages_exact-name drivers/virtio/virtio_pci.c
> --- linux-2.6.git/drivers/virtio/virtio_pci.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.082400957 -0700
> +++ linux-2.6.git-dave/drivers/virtio/virtio_pci.c	2011-04-07 08:37:58.190400949 -0700
> @@ -385,7 +385,7 @@ static struct virtqueue *setup_vq(struct
>  	info->msix_vector = msix_vec;
>  
>  	size = PAGE_ALIGN(vring_size(num, VIRTIO_PCI_VRING_ALIGN));
> -	info->queue = alloc_pages_exact(size, GFP_KERNEL|__GFP_ZERO);
> +	info->queue = get_free_pages_exact(GFP_KERNEL|__GFP_ZERO, size);
>  	if (info->queue == NULL) {
>  		err = -ENOMEM;
>  		goto out_info;
> diff -puN include/linux/gfp.h~change-alloc_pages_exact-name include/linux/gfp.h
> --- linux-2.6.git/include/linux/gfp.h~change-alloc_pages_exact-name	2011-04-07 08:37:58.086400956 -0700
> +++ linux-2.6.git-dave/include/linux/gfp.h	2011-04-07 08:37:58.190400949 -0700
> @@ -351,7 +351,7 @@ extern struct page *alloc_pages_vma(gfp_
>  extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
>  extern unsigned long get_zeroed_page(gfp_t gfp_mask);
>  
> -void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
> +void *get_free_pages_exact(gfp_t gfp_mask, size_t size);
>  void free_pages_exact(void *virt, size_t size);
>  
>  #define __get_free_page(gfp_mask) \
> diff -puN kernel/profile.c~change-alloc_pages_exact-name kernel/profile.c
> --- linux-2.6.git/kernel/profile.c~change-alloc_pages_exact-name	2011-04-07 08:37:58.090400955 -0700
> +++ linux-2.6.git-dave/kernel/profile.c	2011-04-07 08:37:58.190400949 -0700
> @@ -121,7 +121,7 @@ int __ref profile_init(void)
>  	if (prof_buffer)
>  		return 0;
>  
> -	prof_buffer = alloc_pages_exact(buffer_bytes,
> +	prof_buffer = get_free_pages_exact(buffer_bytes,
>  					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
>  	if (prof_buffer)
>  		return 0;

Here either.

Everything else looks good, so once these are corrected:

	Acked-by: David Rientjes <rientjes@google.com>

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Re: [PATCH 1/2] rename alloc_pages_exact()

[Dave Hansen]

On Thu, 2011-04-07 at 14:40 -0700, David Rientjes wrote:
> > alloc_pages_exact() returns a virtual address.  But, alloc_pages() returns
> > a 'struct page *'.  That makes for very confused kernel hackers.
> > 
> > __get_free_pages(), on the other hand, returns virtual addresses.  That
> > makes alloc_pages_exact() a much closer match to __get_free_pages(), so
> > rename it to get_free_pages_exact().
> > 
> 
> The patch also reverses the arguments of the function in 
> include/linux/gfp.h, undoubtedly to resemble the (mask, order) appearance 
> of __get_free_pages():
> 
> 	-void *alloc_pages_exact(size_t size, gfp_t gfp_mask);
> 	+void *get_free_pages_exact(gfp_t gfp_mask, size_t size);

Thanks.  I dumped the fixes for that in the second patch.  Whoops.  Will
repost.

-- Dave

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Re: [PATCH 2/2] make new alloc_pages_exact()

[David Rientjes]

On Thu, 7 Apr 2011, Dave Hansen wrote:

> 
> What I really wanted in the end was a highmem-capable alloc_pages_exact(),
> so here it is.
> 

Perhaps expand upon how the new alloc_pages_exact() works and what it will 
be used for instead of only talking about how it's named?

> It's a bit unfortunate that we have __free_pages_exact() and
> free_pages_exact(), but that mess already exists with __free_pages()
> vs. free_pages_exact().  So, at worst, this mirrors the mess that we
> already have.
> 
> I'm also a bit worried that I've not put in something named
> alloc_pages_exact(), but that behaves differently than it did before this
> set.  I got all of the in-tree cases, but I'm a bit worried about
> stragglers elsewhere.  So, I'm calling this __alloc_pages_exact() for
> the moment.  We can take out the __ some day if it bothers people.
> 
> Note that the __get_free_pages() has a !GFP_HIGHMEM check.  Now that
> we are using alloc_pages_exact() instead of __get_free_pages() for
> get_free_pages_exact(), we had to add a new check in
> get_free_pages_exact().
> 
> This has been compile and boot tested, and I checked that
> 
> 	echo 2 > /sys/kernel/profiling
> 
> still works, since it uses get_free_pages_exact().
> 
> Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
> ---
> 
>  linux-2.6.git-dave/drivers/video/pxafb.c |    4 -
>  linux-2.6.git-dave/include/linux/gfp.h   |    4 +
>  linux-2.6.git-dave/kernel/profile.c      |    4 -
>  linux-2.6.git-dave/mm/page_alloc.c       |   81 +++++++++++++++++++++++--------
>  4 files changed, 69 insertions(+), 24 deletions(-)
> 
> diff -puN include/linux/gfp.h~make_new_alloc_pages_exact include/linux/gfp.h
> --- linux-2.6.git/include/linux/gfp.h~make_new_alloc_pages_exact	2011-04-07 08:41:08.158387017 -0700
> +++ linux-2.6.git-dave/include/linux/gfp.h	2011-04-07 08:41:08.174387016 -0700
> @@ -351,6 +351,10 @@ extern struct page *alloc_pages_vma(gfp_
>  extern unsigned long __get_free_pages(gfp_t gfp_mask, unsigned int order);
>  extern unsigned long get_zeroed_page(gfp_t gfp_mask);
>  
> +/* 'struct page' version */
> +struct page *__alloc_pages_exact(gfp_t, size_t);
> +void __free_pages_exact(struct page *, size_t);

They're not required, but these should have the names of the arguments 
like the other prototypes in this file.

> +/* virtual address version */
>  void *get_free_pages_exact(gfp_t gfp_mask, size_t size);
>  void free_pages_exact(void *virt, size_t size);
>  
> diff -puN mm/page_alloc.c~make_new_alloc_pages_exact mm/page_alloc.c
> --- linux-2.6.git/mm/page_alloc.c~make_new_alloc_pages_exact	2011-04-07 08:41:08.162387016 -0700
> +++ linux-2.6.git-dave/mm/page_alloc.c	2011-04-07 09:44:33.937537711 -0700
> @@ -2318,36 +2318,83 @@ void free_pages(unsigned long addr, unsi
>  EXPORT_SYMBOL(free_pages);
>  
>  /**
> - * get_free_pages_exact - allocate an exact number physically-contiguous pages.
> + * __alloc_pages_exact - allocate an exact number physically-contiguous pages.
>   * @gfp_mask: GFP flags for the allocation
>   * @size: the number of bytes to allocate
> + * returns: struct page for allocated memory
>   *
> - * This function is similar to __get_free_pages(), except that it allocates the
> - * minimum number of pages to satisfy the request.  get_free_pages() can only
> + * This function is similar to alloc_pages(), except that it allocates the
> + * minimum number of pages to satisfy the request.  alloc_pages() can only
>   * allocate memory in power-of-two pages.
>   *
>   * This function is also limited by MAX_ORDER.
>   *
>   * Memory allocated by this function must be released by free_pages_exact().
>   */
> -void *get_free_pages_exact(gfp_t gfp_mask, size_t size)
> +struct page *__alloc_pages_exact(gfp_t gfp_mask, size_t size)
>  {
>  	unsigned int order = get_order(size);
> -	unsigned long addr;
> +	struct page *page;
>  
> -	addr = __get_free_pages(gfp_mask, order);
> -	if (addr) {
> -		unsigned long alloc_end = addr + (PAGE_SIZE << order);
> -		unsigned long used = addr + PAGE_ALIGN(size);
> +	page = alloc_pages(gfp_mask, order);
> +	if (page) {
> +		struct page *alloc_end = page + (1 << order);
> +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;

Wouldn't it better to call this "unused" rather than "used" since it 
represents a cursor over pages that we want to free?

>  
> -		split_page(virt_to_page((void *)addr), order);
> +		split_page(page, order);
>  		while (used < alloc_end) {
> -			free_page(used);
> -			used += PAGE_SIZE;
> +			__free_page(used);
> +			used++;
>  		}
>  	}
>  
> -	return (void *)addr;
> +	return page;
> +}
> +EXPORT_SYMBOL(__alloc_pages_exact);

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Re: [PATCH 2/2] make new alloc_pages_exact()

[Dave Hansen]

On Thu, 2011-04-07 at 15:03 -0700, David Rientjes wrote:
> On Thu, 7 Apr 2011, Dave Hansen wrote:
> > What I really wanted in the end was a highmem-capable alloc_pages_exact(),
> > so here it is.
> 
> Perhaps expand upon how the new alloc_pages_exact() works and what it will 
> be used for instead of only talking about how it's named?

Will do.

> > +/* 'struct page' version */
> > +struct page *__alloc_pages_exact(gfp_t, size_t);
> > +void __free_pages_exact(struct page *, size_t);
> 
> They're not required, but these should have the names of the arguments 
> like the other prototypes in this file.

Fair enough.

> > -	addr = __get_free_pages(gfp_mask, order);
> > -	if (addr) {
> > -		unsigned long alloc_end = addr + (PAGE_SIZE << order);
> > -		unsigned long used = addr + PAGE_ALIGN(size);
> > +	page = alloc_pages(gfp_mask, order);
> > +	if (page) {
> > +		struct page *alloc_end = page + (1 << order);
> > +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
> 
> Wouldn't it better to call this "unused" rather than "used" since it 
> represents a cursor over pages that we want to free?

Yeah, agreed.  I think I screwed this up once when coding this because I
misread it.  I'll change it.

-- Dave

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Re: [PATCH 2/2] make new alloc_pages_exact()

[Michal Nazarewicz]

On Thu, 07 Apr 2011 19:21:05 +0200, Dave Hansen <dave@linux.vnet.ibm.com>  
wrote:
> +struct page *__alloc_pages_exact(gfp_t gfp_mask, size_t size)
>  {
>  	unsigned int order = get_order(size);
> -	unsigned long addr;
> +	struct page *page;
> -	addr = __get_free_pages(gfp_mask, order);
> -	if (addr) {
> -		unsigned long alloc_end = addr + (PAGE_SIZE << order);
> -		unsigned long used = addr + PAGE_ALIGN(size);
> +	page = alloc_pages(gfp_mask, order);
> +	if (page) {
> +		struct page *alloc_end = page + (1 << order);
> +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
> -		split_page(virt_to_page((void *)addr), order);
> +		split_page(page, order);
>  		while (used < alloc_end) {
> -			free_page(used);
> -			used += PAGE_SIZE;
> +			__free_page(used);
> +			used++;
>  		}

Have you thought about moving this loop to a separate function, ie.
_free_page_range(start, end)?  I'm asking because this loop appears
in two places and my CMA would also benefit from such a function.

>  	}
> -	return (void *)addr;
> +	return page;
> +}

-- 
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@google.com>-----ooO--(_)--Ooo--

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Re: [PATCH 2/2] make new alloc_pages_exact()

[Dave Hansen]

On Fri, 2011-04-08 at 14:28 +0200, Michal Nazarewicz wrote:
> On Thu, 07 Apr 2011 19:21:05 +0200, Dave Hansen <dave@linux.vnet.ibm.com>  
> wrote:
> > +struct page *__alloc_pages_exact(gfp_t gfp_mask, size_t size)
> >  {
> >  	unsigned int order = get_order(size);
> > -	unsigned long addr;
> > +	struct page *page;
> > -	addr = __get_free_pages(gfp_mask, order);
> > -	if (addr) {
> > -		unsigned long alloc_end = addr + (PAGE_SIZE << order);
> > -		unsigned long used = addr + PAGE_ALIGN(size);
> > +	page = alloc_pages(gfp_mask, order);
> > +	if (page) {
> > +		struct page *alloc_end = page + (1 << order);
> > +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
> > -		split_page(virt_to_page((void *)addr), order);
> > +		split_page(page, order);
> >  		while (used < alloc_end) {
> > -			free_page(used);
> > -			used += PAGE_SIZE;
> > +			__free_page(used);
> > +			used++;
> >  		}
> 
> Have you thought about moving this loop to a separate function, ie.
> _free_page_range(start, end)?  I'm asking because this loop appears
> in two places and my CMA would also benefit from such a function.

Sounds like a good idea to me.  Were you thinking start/end 'struct
page's as arguments?

-- Dave

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Re: [PATCH 2/2] make new alloc_pages_exact()

[Michal Nazarewicz]

>> On Thu, 07 Apr 2011 19:21:05 +0200, Dave Hansen wrote:
>>>  		while (used < alloc_end) {
>>> -			free_page(used);
>>> -			used += PAGE_SIZE;
>>> +			__free_page(used);
>>> +			used++;
>>>  		}

> On Fri, 2011-04-08 at 14:28 +0200, Michal Nazarewicz wrote:
>> Have you thought about moving this loop to a separate function, ie.
>> _free_page_range(start, end)?  I'm asking because this loop appears
>> in two places and my CMA would also benefit from such a function.

On Fri, 08 Apr 2011 15:19:46 +0200, Dave Hansen wrote:
> Sounds like a good idea to me.  Were you thinking start/end 'struct
> page's as arguments?

Either that or (struct page *start, unsigned nr_pages).

-- 
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.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michal "mina86" Nazarewicz    (o o)
ooo +-----<email/xmpp: mnazarewicz@google.com>-----ooO--(_)--Ooo--

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Re: [PATCH 2/2] make new alloc_pages_exact()

[Dave Hansen]

On Fri, 2011-04-08 at 14:28 +0200, Michal Nazarewicz wrote:
> On Thu, 07 Apr 2011 19:21:05 +0200, Dave Hansen <dave@linux.vnet.ibm.com>  
> > +		struct page *alloc_end = page + (1 << order);
> > +		struct page *used = page + PAGE_ALIGN(size)/PAGE_SIZE;
> > -		split_page(virt_to_page((void *)addr), order);
> > +		split_page(page, order);
> >  		while (used < alloc_end) {
> > -			free_page(used);
> > -			used += PAGE_SIZE;
> > +			__free_page(used);
> > +			used++;
> >  		}
> 
> Have you thought about moving this loop to a separate function, ie.
> _free_page_range(start, end)?  I'm asking because this loop appears
> in two places and my CMA would also benefit from such a function.

It's actually perilously close to free_pages_exact().  I'll try to make
it usable for this case as well.

-- Dave

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