[PATCH] Add __GFP_THISNODE to avoid fallback to other nodes and ignore cpuset/memory policy restrictions

Add a new gfp flag __GFP_THISNODE to avoid fallback to other nodes.  This
flag is essential if a kernel component requires memory to be located on a
certain node.  It will be needed for alloc_pages_node() to force allocation
on the indicated node and for alloc_pages() to force allocation on the
current node.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/gfp.h

@@ -45,6 +45,7 @@ struct vm_area_struct;
 #define __GFP_ZERO	((__force gfp_t)0x8000u)/* Return zeroed page on success */
 #define __GFP_NOMEMALLOC ((__force gfp_t)0x10000u) /* Don't use emergency reserves */
 #define __GFP_HARDWALL   ((__force gfp_t)0x20000u) /* Enforce hardwall cpuset memory allocs */
+#define __GFP_THISNODE	((__force gfp_t)0x40000u)/* No fallback, no policies */
 
 #define __GFP_BITS_SHIFT 20	/* Room for 20 __GFP_FOO bits */
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
@@ -53,7 +54,7 @@ struct vm_area_struct;
 #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| \
-			__GFP_NOMEMALLOC|__GFP_HARDWALL)
+			__GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_THISNODE)
 
 /* This equals 0, but use constants in case they ever change */
 #define GFP_NOWAIT	(GFP_ATOMIC & ~__GFP_HIGH)

kernel/cpuset.c

@@ -2316,7 +2316,7 @@ int __cpuset_zone_allowed(struct zone *z, gfp_t gfp_mask)
 	const struct cpuset *cs;	/* current cpuset ancestors */
 	int allowed;			/* is allocation in zone z allowed? */
 
-	if (in_interrupt())
+	if (in_interrupt() || (gfp_mask & __GFP_THISNODE))
 		return 1;
 	node = z->zone_pgdat->node_id;
 	might_sleep_if(!(gfp_mask & __GFP_HARDWALL));

mm/mempolicy.c

@@ -1290,7 +1290,7 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
 
 	if ((gfp & __GFP_WAIT) && !in_interrupt())
 		cpuset_update_task_memory_state();
-	if (!pol || in_interrupt())
+	if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
 		pol = &default_policy;
 	if (pol->policy == MPOL_INTERLEAVE)
 		return alloc_page_interleave(gfp, order, interleave_nodes(pol));

mm/page_alloc.c

@@ -893,6 +893,9 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
 	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
 	 */
 	do {
+		if (unlikely((gfp_mask & __GFP_THISNODE) &&
+			(*z)->zone_pgdat != zonelist->zones[0]->zone_pgdat))
+				break;
 		if ((alloc_flags & ALLOC_CPUSET) &&
 				!cpuset_zone_allowed(*z, gfp_mask))
 			continue;