The compound page logic is a little fragile - it relies on additional
metadata in the pageframes which some other kernel code likes to stomp on
(xfs was doing this).
Also, because we're treating all higher-order pages as compound pages it is
no longer possible to free individual lower-order pages from the middle of
higher-order pages. At least one ARM driver insists on doing this.
We only really need the compound page logic for higher-order pages which can
be mapped into user pagetables and placed under direct-io. This covers
hugetlb pages and, conceivably, soundcard DMA buffers which were allcoated
with a higher-order allocation but which weren't marked PageReserved.
The patch arranges for the hugetlb implications to allocate their pages with
compound page metadata, and all other higher-order allocations go back to the
old way.
(Andrea supplied the GFP_LEVEL_MASK fix)
---
25-akpm/arch/i386/mm/hugetlbpage.c | 3 ++-
25-akpm/arch/ia64/mm/hugetlbpage.c | 3 ++-
25-akpm/arch/ppc64/mm/hugetlbpage.c | 3 ++-
25-akpm/arch/sh/mm/hugetlbpage.c | 3 ++-
25-akpm/arch/sparc64/mm/hugetlbpage.c | 3 ++-
25-akpm/include/linux/gfp.h | 6 ++++++
25-akpm/include/linux/mm.h | 4 ++--
25-akpm/include/linux/slab.h | 4 +---
25-akpm/mm/page_alloc.c | 22 +++++++++++-----------
include/linux/page-flags.h | 0
10 files changed, 30 insertions(+), 21 deletions(-)
diff -puN include/linux/page-flags.h~use-compound-pages-for-hugetlb-only include/linux/page-flags.h
diff -puN mm/page_alloc.c~use-compound-pages-for-hugetlb-only mm/page_alloc.c
--- 25/mm/page_alloc.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/mm/page_alloc.c Thu Apr 8 14:43:06 2004
@@ -130,6 +130,9 @@ static void destroy_compound_page(struct
int i;
int nr_pages = 1 << order;
+ if (!PageCompound(page))
+ return;
+
if (page[1].index != order)
bad_page(__FUNCTION__, page);
@@ -487,10 +490,12 @@ void fastcall free_cold_page(struct page
* or two.
*/
-static struct page *buffered_rmqueue(struct zone *zone, int order, int cold)
+static struct page *
+buffered_rmqueue(struct zone *zone, int order, int gfp_flags)
{
unsigned long flags;
struct page *page = NULL;
+ int cold = !!(gfp_flags & __GFP_COLD);
if (order == 0) {
struct per_cpu_pages *pcp;
@@ -519,7 +524,7 @@ static struct page *buffered_rmqueue(str
BUG_ON(bad_range(zone, page));
mod_page_state_zone(zone, pgalloc, 1 << order);
prep_new_page(page, order);
- if (order)
+ if (order && (gfp_flags & __GFP_COMP))
prep_compound_page(page, order);
}
return page;
@@ -552,16 +557,11 @@ __alloc_pages(unsigned int gfp_mask, uns
struct reclaim_state reclaim_state;
struct task_struct *p = current;
int i;
- int cold;
int alloc_type;
int do_retry;
might_sleep_if(wait);
- cold = 0;
- if (gfp_mask & __GFP_COLD)
- cold = 1;
-
zones = zonelist->zones; /* the list of zones suitable for gfp_mask */
if (zones[0] == NULL) /* no zones in the zonelist */
return NULL;
@@ -583,7 +583,7 @@ __alloc_pages(unsigned int gfp_mask, uns
if (z->free_pages >= min ||
(!wait && z->free_pages >= z->pages_high)) {
- page = buffered_rmqueue(z, order, cold);
+ page = buffered_rmqueue(z, order, gfp_mask);
if (page)
goto got_pg;
}
@@ -606,7 +606,7 @@ __alloc_pages(unsigned int gfp_mask, uns
if (z->free_pages >= min ||
(!wait && z->free_pages >= z->pages_high)) {
- page = buffered_rmqueue(z, order, cold);
+ page = buffered_rmqueue(z, order, gfp_mask);
if (page)
goto got_pg;
}
@@ -620,7 +620,7 @@ rebalance:
for (i = 0; zones[i] != NULL; i++) {
struct zone *z = zones[i];
- page = buffered_rmqueue(z, order, cold);
+ page = buffered_rmqueue(z, order, gfp_mask);
if (page)
goto got_pg;
}
@@ -648,7 +648,7 @@ rebalance:
if (z->free_pages >= min ||
(!wait && z->free_pages >= z->pages_high)) {
- page = buffered_rmqueue(z, order, cold);
+ page = buffered_rmqueue(z, order, gfp_mask);
if (page)
goto got_pg;
}
diff -puN arch/i386/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only arch/i386/mm/hugetlbpage.c
--- 25/arch/i386/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/arch/i386/mm/hugetlbpage.c Thu Apr 8 15:01:26 2004
@@ -54,7 +54,8 @@ static struct page *alloc_fresh_huge_pag
{
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER, HUGETLB_PAGE_ORDER);
+ page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP,
+ HUGETLB_PAGE_ORDER);
nid = (nid + 1) % numnodes;
return page;
}
diff -puN arch/ia64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only arch/ia64/mm/hugetlbpage.c
--- 25/arch/ia64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/arch/ia64/mm/hugetlbpage.c Thu Apr 8 15:01:26 2004
@@ -58,7 +58,8 @@ static struct page *alloc_fresh_huge_pag
{
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER, HUGETLB_PAGE_ORDER);
+ page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP,
+ HUGETLB_PAGE_ORDER);
nid = (nid + 1) % numnodes;
return page;
}
diff -puN arch/ppc64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only arch/ppc64/mm/hugetlbpage.c
--- 25/arch/ppc64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/arch/ppc64/mm/hugetlbpage.c Thu Apr 8 15:01:26 2004
@@ -78,7 +78,8 @@ static struct page *alloc_fresh_huge_pag
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER, HUGETLB_PAGE_ORDER);
+ page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP,
+ HUGETLB_PAGE_ORDER);
if (!page)
return NULL;
diff -puN arch/sh/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only arch/sh/mm/hugetlbpage.c
--- 25/arch/sh/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/arch/sh/mm/hugetlbpage.c Thu Apr 8 15:01:26 2004
@@ -60,7 +60,8 @@ static struct page *alloc_fresh_huge_pag
{
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER, HUGETLB_PAGE_ORDER);
+ page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP,
+ HUGETLB_PAGE_ORDER);
nid = (nid + 1) % numnodes;
return page;
}
diff -puN arch/sparc64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only arch/sparc64/mm/hugetlbpage.c
--- 25/arch/sparc64/mm/hugetlbpage.c~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/arch/sparc64/mm/hugetlbpage.c Thu Apr 8 15:01:34 2004
@@ -56,7 +56,8 @@ static struct page *alloc_fresh_huge_pag
{
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER, HUGETLB_PAGE_ORDER);
+ page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP,
+ HUGETLB_PAGE_ORDER);
nid = (nid + 1) % numnodes;
return page;
}
diff -puN include/linux/gfp.h~use-compound-pages-for-hugetlb-only include/linux/gfp.h
--- 25/include/linux/gfp.h~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/include/linux/gfp.h Thu Apr 8 15:01:40 2004
@@ -32,10 +32,16 @@
#define __GFP_NOFAIL 0x800 /* Retry for ever. Cannot fail */
#define __GFP_NORETRY 0x1000 /* Do not retry. Might fail */
#define __GFP_NO_GROW 0x2000 /* Slab internal usage */
+#define __GFP_COMP 0x4000 /* Add compound page metadata */
#define __GFP_BITS_SHIFT 16 /* Room for 16 __GFP_FOO bits */
#define __GFP_BITS_MASK ((1 << __GFP_BITS_SHIFT) - 1)
+/* if you forget to add the bitmask here kernel will crash, period */
+#define GFP_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS| \
+ __GFP_COLD|__GFP_NOWARN|__GFP_REPEAT| \
+ __GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP)
+
#define GFP_ATOMIC (__GFP_HIGH)
#define GFP_NOIO (__GFP_WAIT)
#define GFP_NOFS (__GFP_WAIT | __GFP_IO)
diff -puN include/linux/mm.h~use-compound-pages-for-hugetlb-only include/linux/mm.h
--- 25/include/linux/mm.h~use-compound-pages-for-hugetlb-only Thu Apr 8 14:28:32 2004
+++ 25-akpm/include/linux/mm.h Thu Apr 8 15:01:35 2004
@@ -247,14 +247,14 @@ static inline int page_count(struct page
static inline void get_page(struct page *page)
{
- if (PageCompound(page))
+ if (unlikely(PageCompound(page)))
page = (struct page *)page->private;
atomic_inc(&page->count);
}
static inline void put_page(struct page *page)
{
- if (PageCompound(page)) {
+ if (unlikely(PageCompound(page))) {
page = (struct page *)page->private;
if (put_page_testzero(page)) {
if (page[1].mapping) { /* destructor? */
diff -puN include/linux/slab.h~use-compound-pages-for-hugetlb-only include/linux/slab.h
--- 25/include/linux/slab.h~use-compound-pages-for-hugetlb-only Thu Apr 8 15:01:40 2004
+++ 25-akpm/include/linux/slab.h Thu Apr 8 15:01:40 2004
@@ -25,9 +25,7 @@ typedef struct kmem_cache_s kmem_cache_t
#define SLAB_KERNEL GFP_KERNEL
#define SLAB_DMA GFP_DMA
-#define SLAB_LEVEL_MASK (__GFP_WAIT|__GFP_HIGH|__GFP_IO|__GFP_FS|\
- __GFP_COLD|__GFP_NOWARN|__GFP_REPEAT|\
- __GFP_NOFAIL|__GFP_NORETRY)
+#define SLAB_LEVEL_MASK GFP_LEVEL_MASK
#define SLAB_NO_GROW __GFP_NO_GROW /* don't grow a cache */
_