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authorNick Piggin <npiggin@suse.de>2006-03-22 00:08:05 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-22 07:53:57 -0800
commit8dfcc9ba27e2ed257e5de9539f7f03e57c2c0e33 (patch)
treeaecaeb6a0b33c23f79dfcd2418e4a3881a29f2e2
parent8e7a9aae91101916b86de07fafe3272ea8dc1f10 (diff)
downloadlinux-2.6.34-ux500-8dfcc9ba27e2ed257e5de9539f7f03e57c2c0e33.tar.gz
[PATCH] mm: split highorder pages
Have an explicit mm call to split higher order pages into individual pages. Should help to avoid bugs and be more explicit about the code's intention. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/arm/mm/consistent.c4
-rw-r--r--arch/frv/mm/dma-alloc.c4
-rw-r--r--arch/mips/mm/init.c5
-rw-r--r--arch/ppc/kernel/dma-mapping.c4
-rw-r--r--arch/sh/mm/consistent.c3
-rw-r--r--arch/xtensa/mm/pgtable.c10
-rw-r--r--include/linux/mm.h6
-rw-r--r--mm/memory.c4
-rw-r--r--mm/page_alloc.c22
9 files changed, 41 insertions, 21 deletions
diff --git a/arch/arm/mm/consistent.c b/arch/arm/mm/consistent.c
index c2ee18d2075..8a1bfcd5008 100644
--- a/arch/arm/mm/consistent.c
+++ b/arch/arm/mm/consistent.c
@@ -223,6 +223,8 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
pte = consistent_pte[idx] + off;
c->vm_pages = page;
+ split_page(page, order);
+
/*
* Set the "dma handle"
*/
@@ -231,7 +233,6 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
do {
BUG_ON(!pte_none(*pte));
- set_page_count(page, 1);
/*
* x86 does not mark the pages reserved...
*/
@@ -250,7 +251,6 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
* Free the otherwise unused pages.
*/
while (page < end) {
- set_page_count(page, 1);
__free_page(page);
page++;
}
diff --git a/arch/frv/mm/dma-alloc.c b/arch/frv/mm/dma-alloc.c
index 342823aad75..636b2f8b5d9 100644
--- a/arch/frv/mm/dma-alloc.c
+++ b/arch/frv/mm/dma-alloc.c
@@ -115,9 +115,7 @@ void *consistent_alloc(gfp_t gfp, size_t size, dma_addr_t *dma_handle)
*/
if (order > 0) {
struct page *rpage = virt_to_page(page);
-
- for (i = 1; i < (1 << order); i++)
- set_page_count(rpage + i, 1);
+ split_page(rpage, order);
}
err = 0;
diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 0ff9a348b84..a140da9732d 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -54,7 +54,8 @@ unsigned long empty_zero_page, zero_page_mask;
*/
unsigned long setup_zero_pages(void)
{
- unsigned long order, size;
+ unsigned int order;
+ unsigned long size;
struct page *page;
if (cpu_has_vce)
@@ -67,9 +68,9 @@ unsigned long setup_zero_pages(void)
panic("Oh boy, that early out of memory?");
page = virt_to_page(empty_zero_page);
+ split_page(page, order);
while (page < virt_to_page(empty_zero_page + (PAGE_SIZE << order))) {
SetPageReserved(page);
- set_page_count(page, 1);
page++;
}
diff --git a/arch/ppc/kernel/dma-mapping.c b/arch/ppc/kernel/dma-mapping.c
index 685fd0defe2..61465ec88bc 100644
--- a/arch/ppc/kernel/dma-mapping.c
+++ b/arch/ppc/kernel/dma-mapping.c
@@ -223,6 +223,8 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
pte_t *pte = consistent_pte + CONSISTENT_OFFSET(vaddr);
struct page *end = page + (1 << order);
+ split_page(page, order);
+
/*
* Set the "dma handle"
*/
@@ -231,7 +233,6 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
do {
BUG_ON(!pte_none(*pte));
- set_page_count(page, 1);
SetPageReserved(page);
set_pte_at(&init_mm, vaddr,
pte, mk_pte(page, pgprot_noncached(PAGE_KERNEL)));
@@ -244,7 +245,6 @@ __dma_alloc_coherent(size_t size, dma_addr_t *handle, gfp_t gfp)
* Free the otherwise unused pages.
*/
while (page < end) {
- set_page_count(page, 1);
__free_page(page);
page++;
}
diff --git a/arch/sh/mm/consistent.c b/arch/sh/mm/consistent.c
index df3a9e452cc..ee73e30263a 100644
--- a/arch/sh/mm/consistent.c
+++ b/arch/sh/mm/consistent.c
@@ -23,6 +23,7 @@ void *consistent_alloc(gfp_t gfp, size_t size, dma_addr_t *handle)
page = alloc_pages(gfp, order);
if (!page)
return NULL;
+ split_page(page, order);
ret = page_address(page);
*handle = virt_to_phys(ret);
@@ -37,8 +38,6 @@ void *consistent_alloc(gfp_t gfp, size_t size, dma_addr_t *handle)
end = page + (1 << order);
while (++page < end) {
- set_page_count(page, 1);
-
/* Free any unused pages */
if (page >= free) {
__free_page(page);
diff --git a/arch/xtensa/mm/pgtable.c b/arch/xtensa/mm/pgtable.c
index cbc56aedf13..7d28914d11c 100644
--- a/arch/xtensa/mm/pgtable.c
+++ b/arch/xtensa/mm/pgtable.c
@@ -21,13 +21,9 @@ pte_t* pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
p = (pte_t*) __get_free_pages(GFP_KERNEL|__GFP_REPEAT, COLOR_ORDER);
if (likely(p)) {
- struct page *page;
+ split_page(virt_to_page(p), COLOR_ORDER);
for (i = 0; i < COLOR_SIZE; i++) {
- page = virt_to_page(p);
-
- set_page_count(page, 1);
-
if (ADDR_COLOR(p) == color)
pte = p;
else
@@ -55,9 +51,9 @@ struct page* pte_alloc_one(struct mm_struct *mm, unsigned long address)
p = alloc_pages(GFP_KERNEL | __GFP_REPEAT, PTE_ORDER);
if (likely(p)) {
- for (i = 0; i < PAGE_ORDER; i++) {
- set_page_count(p, 1);
+ split_page(p, COLOR_ORDER);
+ for (i = 0; i < PAGE_ORDER; i++) {
if (PADDR_COLOR(page_address(p)) == color)
page = p;
else
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9bbddf228cd..e67980654c4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -328,6 +328,12 @@ static inline void get_page(struct page *page)
void put_page(struct page *page);
+#ifdef CONFIG_MMU
+void split_page(struct page *page, unsigned int order);
+#else
+static inline void split_page(struct page *page, unsigned int order) {}
+#endif
+
/*
* Multiple processes may "see" the same page. E.g. for untouched
* mappings of /dev/null, all processes see the same page full of
diff --git a/mm/memory.c b/mm/memory.c
index 85e80a57db2..6af555c1c42 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1221,9 +1221,7 @@ out:
* The page has to be a nice clean _individual_ kernel allocation.
* If you allocate a compound page, you need to have marked it as
* such (__GFP_COMP), or manually just split the page up yourself
- * (which is mainly an issue of doing "set_page_count(page, 1)" for
- * each sub-page, and then freeing them one by one when you free
- * them rather than freeing it as a compound page).
+ * (see split_page()).
*
* NOTE! Traditionally this was done with "remap_pfn_range()" which
* took an arbitrary page protection parameter. This doesn't allow
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 10291985135..fc65e87368b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -752,6 +752,28 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
clear_highpage(page + i);
}
+#ifdef CONFIG_MMU
+/*
+ * split_page takes a non-compound higher-order page, and splits it into
+ * n (1<<order) sub-pages: page[0..n]
+ * Each sub-page must be freed individually.
+ *
+ * Note: this is probably too low level an operation for use in drivers.
+ * Please consult with lkml before using this in your driver.
+ */
+void split_page(struct page *page, unsigned int order)
+{
+ int i;
+
+ BUG_ON(PageCompound(page));
+ BUG_ON(!page_count(page));
+ for (i = 1; i < (1 << order); i++) {
+ BUG_ON(page_count(page + i));
+ set_page_count(page + i, 1);
+ }
+}
+#endif
+
/*
* Really, prep_compound_page() should be called from __rmqueue_bulk(). But
* we cheat by calling it from here, in the order > 0 path. Saves a branch