[PATCH] swiotlb: make sure initial DMA allocations really are in DMA memory

This introduces a limit parameter to the core bootmem allocator; The new
parameter indicates that physical memory allocated by the bootmem
allocator should be within the requested limit.

We also introduce alloc_bootmem_low_pages_limit, alloc_bootmem_node_limit,
alloc_bootmem_low_pages_node_limit apis, but alloc_bootmem_low_pages_limit
is the only api used for swiotlb.

The existing alloc_bootmem_low_pages() api could instead have been
changed and made to pass right limit to the core allocator.  But that
would make the patch more intrusive for 2.6.14, as other arches use
alloc_bootmem_low_pages().  We may be done that post 2.6.14 as a
cleanup.

With this, swiotlb gets memory within 4G for both x86_64 and ia64
arches.

Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Ravikiran G Thirumalai <kiran@scalex86.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 21 insertions, 10 deletions

diff --git a/mm/bootmem.c b/mm/bootmem.c
index c1330cc1978..a58699b6579 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -154,10 +154,10 @@ static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
  */
 static void * __init
 __alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
-		unsigned long align, unsigned long goal)
+	      unsigned long align, unsigned long goal, unsigned long limit)
 {
 	unsigned long offset, remaining_size, areasize, preferred;
-	unsigned long i, start = 0, incr, eidx;
+	unsigned long i, start = 0, incr, eidx, end_pfn = bdata->node_low_pfn;
 	void *ret;
 
 	if(!size) {
@@ -166,7 +166,14 @@ __alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
 	}
 	BUG_ON(align & (align-1));
 
-	eidx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
+	if (limit && bdata->node_boot_start >= limit)
+		return NULL;
+
+        limit >>=PAGE_SHIFT;
+	if (limit && end_pfn > limit)
+		end_pfn = limit;
+
+	eidx = end_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
 	offset = 0;
 	if (align &&
 	    (bdata->node_boot_start & (align - 1UL)) != 0)
@@ -178,11 +185,12 @@ __alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
 	 * first, then we try to allocate lower pages.
 	 */
 	if (goal && (goal >= bdata->node_boot_start) && 
-	    ((goal >> PAGE_SHIFT) < bdata->node_low_pfn)) {
+	    ((goal >> PAGE_SHIFT) < end_pfn)) {
 		preferred = goal - bdata->node_boot_start;
 
 		if (bdata->last_success >= preferred)
-			preferred = bdata->last_success;
+			if (!limit || (limit && limit > bdata->last_success))
+				preferred = bdata->last_success;
 	} else
 		preferred = 0;
 
@@ -382,14 +390,15 @@ unsigned long __init free_all_bootmem (void)
 	return(free_all_bootmem_core(NODE_DATA(0)));
 }
 
-void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned long goal)
+void * __init __alloc_bootmem_limit (unsigned long size, unsigned long align, unsigned long goal,
+				unsigned long limit)
 {
 	pg_data_t *pgdat = pgdat_list;
 	void *ptr;
 
 	for_each_pgdat(pgdat)
 		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
-						align, goal)))
+						 align, goal, limit)))
 			return(ptr);
 
 	/*
@@ -400,14 +409,16 @@ void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned
 	return NULL;
 }
 
-void * __init __alloc_bootmem_node (pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal)
+
+void * __init __alloc_bootmem_node_limit (pg_data_t *pgdat, unsigned long size, unsigned long align,
+				     unsigned long goal, unsigned long limit)
 {
 	void *ptr;
 
-	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal);
+	ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, limit);
 	if (ptr)
 		return (ptr);
 
-	return __alloc_bootmem(size, align, goal);
+	return __alloc_bootmem_limit(size, align, goal, limit);
 }