[RFC][PATCH 1/2] rename alloc_pages_exact()

[RFC][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>
---

 linux-2.6.git-dave/drivers/video/fsl-diu-fb.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             |   22 +++++++++++-----------
 6 files changed, 17 insertions(+), 17 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	2011-03-22 12:11:56.905452820 -0700
+++ linux-2.6.git-dave/drivers/video/fsl-diu-fb.c	2011-03-22 12:11:56.937452815 -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(size, GFP_DMA | __GFP_ZERO);
 	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	2011-03-22 12:11:56.909452819 -0700
+++ linux-2.6.git-dave/drivers/video/pxafb.c	2011-03-22 12:11:56.941452815 -0700
@@ -820,7 +820,7 @@ static int overlayfb_map_video_memory(st
 		free_pages_exact(ofb->video_mem, ofb->video_mem_size);
 	}
 
-	ofb->video_mem = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+	ofb->video_mem = get_free_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
 	if (ofb->video_mem == NULL)
 		return -ENOMEM;
 
@@ -1678,7 +1678,7 @@ 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(size, GFP_KERNEL | __GFP_ZERO);
 	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	2011-03-22 12:11:56.913452818 -0700
+++ linux-2.6.git-dave/drivers/virtio/virtio_pci.c	2011-03-22 12:11:56.941452815 -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(size, GFP_KERNEL|__GFP_ZERO);
 	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	2011-03-22 12:11:56.917452818 -0700
+++ linux-2.6.git-dave/include/linux/gfp.h	2011-03-22 12:11:56.945452815 -0700
@@ -346,7 +346,7 @@ 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(size_t size, gfp_t gfp_mask);
 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	2011-03-22 12:11:56.921452818 -0700
+++ linux-2.6.git-dave/kernel/profile.c	2011-03-22 12:11:56.941452815 -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	2011-03-22 12:11:56.925452818 -0700
+++ linux-2.6.git-dave/mm/page_alloc.c	2011-03-22 12:11:56.937452815 -0700
@@ -2284,19 +2284,19 @@ void free_pages(unsigned long addr, unsi
 EXPORT_SYMBOL(free_pages);
 
 /**
- * alloc_pages_exact - allocate an exact number physically-contiguous pages.
+ * get_free_pages_exact - allocate an exact number physically-contiguous pages.
  * @size: the number of bytes to allocate
  * @gfp_mask: GFP flags for the allocation
  *
- * 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(size_t size, gfp_t gfp_mask)
 {
 	unsigned int order = get_order(size);
 	unsigned long addr;
@@ -2315,14 +2315,14 @@ 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)
 {
@@ -5247,10 +5247,10 @@ 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(size, GFP_ATOMIC);
 				kmemleak_alloc(table, size, 1, GFP_ATOMIC);
 			}
 		}
_

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[RFC][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.  I got all of the
in-tree cases, but I'm a bit worried about stragglers elsewheree

Note that the __get_free_pages() has a !GFP_HIGHMEM check.  Now that
we're not using it, we had to add a new check to get_free_pages_exact().

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

 linux-2.6.git-dave/include/linux/gfp.h |    4 +
 linux-2.6.git-dave/mm/page_alloc.c     |   81 ++++++++++++++++++++++++---------
 2 files changed, 65 insertions(+), 20 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	2011-03-22 12:11:57.557452739 -0700
+++ linux-2.6.git-dave/include/linux/gfp.h	2011-03-22 12:11:57.573452738 -0700
@@ -346,6 +346,10 @@ 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 gfp_mask, size_t);
+void __free_pages_exact(struct page *page, size_t size);
+/* virtual address version */
 void *get_free_pages_exact(size_t size, gfp_t gfp_mask);
 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	2011-03-22 12:11:57.561452738 -0700
+++ linux-2.6.git-dave/mm/page_alloc.c	2011-03-22 12:11:57.573452738 -0700
@@ -2284,36 +2284,83 @@ 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.
  * @size: the number of bytes to allocate
  * @gfp_mask: GFP flags for the allocation
+ * 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(size_t size, gfp_t gfp_mask)
+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(page);
+			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.
+ * @size: the number of bytes to allocate
+ * @gfp_mask: GFP flags for the allocation
+ * 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(size_t size, gfp_t gfp_mask)
+{
+	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);
 
@@ -2326,13 +2373,7 @@ 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);
 
_

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

[Andi Kleen]

On Tue, Mar 22, 2011 at 12:15:02PM -0700, 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().
> 
> 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.

Yes, that was wrong from the start. Thanks for fixing.

Acked-by: Andi Kleen <ak@linux.intel.com>

-Andi

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

[Dave Hansen]

On Tue, 2011-03-22 at 12:15 -0700, Dave Hansen wrote:
> 
>                 while (used < alloc_end) {
> -                       free_page(used);
> -                       used += PAGE_SIZE;
> +                       __free_page(page);
> +                       used++;
>                 } 

Please note that I'm a dummy and put "page" in there instead of "used".
I'll repost these with a proper inclusion request soon.

-- Dave

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