: Cleanup of __alloc_pages

@@ -707,9 +707,7 @@
 		}
 		local_irq_restore(flags);
 		put_cpu();
-	}
-
-	if (page == NULL) {
+	} else {
 		spin_lock_irqsave(&zone->lock, flags);
 		page = __rmqueue(zone, order);
 		spin_unlock_irqrestore(&zone->lock, flags);

@@ -770,6 +768,45 @@
 	return 1;
 }
 
+/* get_page_from_freeliest loops through all the possible zones
+ * to find out if it can allocate a page.  can_try_harder can have following
+ * values:
+ * -1 => No need to check for the watermarks.
+ *  0 => Don't go too low down in deeps below the low watermark (GFP_HIGH)
+ *  1 => Go far below the low watermark.  See zone_watermark_ok (RT TASK)
+ *
+ * cpuset check is not performed when the skip_cpuset_chk flag is set.
+ */
+
+static struct page *
+get_page_from_freelist(gfp_t gfp_mask, unsigned int order, struct zone **zones, 
+			int can_try_harder, int skip_cpuset_chk)
+{
+	struct zone *z;
+	struct page *page = NULL;
+	int classzone_idx = zone_idx(zones[0]);
+	int i;
+
+	/*
+	 * Go through the zonelist once, looking for a zone with enough free.
+	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+	 */
+	for (i = 0; (z = zones[i]) != NULL; i++) {
+		if (!skip_cpuset_chk && (!cpuset_zone_allowed(z, gfp_mask)))
+			continue;
+		if ((can_try_harder >= 0) &&
+			(!zone_watermark_ok(z, order, z->pages_low,
+				       classzone_idx, can_try_harder,
+				       gfp_mask & __GFP_HIGH)))
+			continue;
+
+		page = buffered_rmqueue(z, order, gfp_mask);
+		if (page)
+			break;
+	}
+	return page;
+}
+
 /*
  * This is the 'heart' of the zoned buddy allocator.
  */

@@ -778,15 +815,13 @@
 		struct zonelist *zonelist)
 {
 	const int wait = gfp_mask & __GFP_WAIT;
-	struct zone **zones, *z;
+	struct zone **zones, *z = NULL;
 	struct page *page;
 	struct reclaim_state reclaim_state;
 	struct task_struct *p = current;
 	int i;
-	int classzone_idx;
 	int do_retry;
 	int can_try_harder;
-	int did_some_progress;
 
 	might_sleep_if(wait);
 

@@ -803,42 +838,10 @@
 		/* Should this ever happen?? */
 		return NULL;
 	}
-
-	classzone_idx = zone_idx(zones[0]);
-
 restart:
-	/*
-	 * Go through the zonelist once, looking for a zone with enough free.
-	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
-	 */
-	for (i = 0; (z = zones[i]) != NULL; i++) {
-		int do_reclaim = should_reclaim_zone(z, gfp_mask);
-
-		if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
-			continue;
-
-		/*
-		 * If the zone is to attempt early page reclaim then this loop
-		 * will try to reclaim pages and check the watermark a second
-		 * time before giving up and falling back to the next zone.
-		 */
-zone_reclaim_retry:
-		if (!zone_watermark_ok(z, order, z->pages_low,
-				       classzone_idx, 0, 0)) {
-			if (!do_reclaim)
-				continue;
-			else {
-				zone_reclaim(z, gfp_mask, order);
-				/* Only try reclaim once */
-				do_reclaim = 0;
-				goto zone_reclaim_retry;
-			}
-		}
-
-		page = buffered_rmqueue(z, order, gfp_mask);
-		if (page)
-			goto got_pg;
-	}
+	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order, zones, 0, 0);
+	if (page)
+		goto got_pg;
 
 	for (i = 0; (z = zones[i]) != NULL; i++)
 		wakeup_kswapd(z, order);

@@ -851,19 +854,11 @@
 	 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
 	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
 	 */
-	for (i = 0; (z = zones[i]) != NULL; i++) {
-		if (!zone_watermark_ok(z, order, z->pages_min,
-				       classzone_idx, can_try_harder,
-				       gfp_mask & __GFP_HIGH))
-			continue;
-
-		if (wait && !cpuset_zone_allowed(z, gfp_mask))
-			continue;
-
-		page = buffered_rmqueue(z, order, gfp_mask);
-		if (page)
-			goto got_pg;
-	}
+	if (!wait)
+		page = get_page_from_freelist(gfp_mask, order, zones,
+						can_try_harder, 1);
+	if (page)
+		goto got_pg;
 
 	/* This allocation should allow future memory freeing. */
 

@@ -871,13 +866,9 @@
 			&& !in_interrupt()) {
 		if (!(gfp_mask & __GFP_NOMEMALLOC)) {
 			/* go through the zonelist yet again, ignoring mins */
-			for (i = 0; (z = zones[i]) != NULL; i++) {
-				if (!cpuset_zone_allowed(z, gfp_mask))
-					continue;
-				page = buffered_rmqueue(z, order, gfp_mask);
-				if (page)
-					goto got_pg;
-			}
+			page = get_page_from_freelist(gfp_mask, order, zones, -1, 1);
+			if (page)
+				goto got_pg;
 		}
 		goto nopage;
 	}

@@ -894,47 +885,20 @@
 	reclaim_state.reclaimed_slab = 0;
 	p->reclaim_state = &reclaim_state;
 
-	did_some_progress = try_to_free_pages(zones, gfp_mask);
+	try_to_free_pages(zones, gfp_mask);
 
 	p->reclaim_state = NULL;
 	p->flags &= ~PF_MEMALLOC;
 
 	cond_resched();
 
-	if (likely(did_some_progress)) {
-		for (i = 0; (z = zones[i]) != NULL; i++) {
-			if (!zone_watermark_ok(z, order, z->pages_min,
-					       classzone_idx, can_try_harder,
-					       gfp_mask & __GFP_HIGH))
-				continue;
-
-			if (!cpuset_zone_allowed(z, gfp_mask))
-				continue;
-
-			page = buffered_rmqueue(z, order, gfp_mask);
-			if (page)
-				goto got_pg;
-		}
-	} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
+	page = get_page_from_freelist(gfp_mask, order, zones, can_try_harder, 0);
+	if (page)
+		goto got_pg;
+	if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
 		/*
-		 * Go through the zonelist yet one more time, keep
-		 * very high watermark here, this is only to catch
-		 * a parallel oom killing, we must fail if we're still
-		 * under heavy pressure.
+		 * Start the OOM here.
 		 */
-		for (i = 0; (z = zones[i]) != NULL; i++) {
-			if (!zone_watermark_ok(z, order, z->pages_high,
-					       classzone_idx, 0, 0))
-				continue;
-
-			if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
-				continue;
-
-			page = buffered_rmqueue(z, order, gfp_mask);
-			if (page)
-				goto got_pg;
-		}
-
 		out_of_memory(gfp_mask, order);
 		goto restart;
 	}

@@ -968,7 +932,7 @@
 	}
 	return NULL;
 got_pg:
-	zone_statistics(zonelist, z);
+	zone_statistics(zonelist, page_zone(page));
 	return page;
 }
 

Index: linux-2.6/mm/page_alloc.c
===================================================================
@@ -707,9 +707,7 @@ buffered_rmqueue(struct zone *zone, int 
 		}
 		local_irq_restore(flags);
 		put_cpu();
-	}
-
-	if (page == NULL) {
+	} else {
 		spin_lock_irqsave(&zone->lock, flags);
 		page = __rmqueue(zone, order);
 		spin_unlock_irqrestore(&zone->lock, flags);

@@ -729,20 +727,25 @@ buffered_rmqueue(struct zone *zone, int 
 	return page;
 }
 
+#define ALLOC_WATERMARKS	0x01 /* check watermarks */
+#define ALLOC_HARDER		0x02 /* try to alloc harder */
+#define ALLOC_HIGH		0x04 /* __GFP_HIGH set */
+#define ALLOC_CPUSET		0x08 /* check for correct cpuset */
+
 /*
  * Return 1 if free pages are above 'mark'. This takes into account the order
  * of the allocation.
  */
 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
-		      int classzone_idx, int can_try_harder, int gfp_high)
+		      int classzone_idx, int alloc_flags)
 {
 	/* free_pages my go negative - that's OK */
 	long min = mark, free_pages = z->free_pages - (1 << order) + 1;
 	int o;
 
-	if (gfp_high)
+	if (alloc_flags & ALLOC_HIGH)
 		min -= min / 2;
-	if (can_try_harder)
+	if (alloc_flags & ALLOC_HARDER)
 		min -= min / 4;
 
 	if (free_pages <= min + z->lowmem_reserve[classzone_idx])

@@ -760,14 +763,41 @@ int zone_watermark_ok(struct zone *z, in
 	return 1;
 }
 
-static inline int
-should_reclaim_zone(struct zone *z, gfp_t gfp_mask)
-{
-	if (!z->reclaim_pages)
-		return 0;
-	if (gfp_mask & __GFP_NORECLAIM)
-		return 0;
-	return 1;
+/*
+ * get_page_from_freeliest goes through the zonelist trying to allocate
+ * a page.
+ */
+static struct page *
+get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
+		struct zonelist *zonelist, int alloc_flags)
+{
+	struct zone **z = zonelist->zones;
+	struct page *page = NULL;
+	int classzone_idx = zone_idx(*z);
+
+	/*
+	 * Go through the zonelist once, looking for a zone with enough free.
+	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+	 */
+	do {
+		if ((alloc_flags & ALLOC_CPUSET) &&
+				!cpuset_zone_allowed(*z, gfp_mask))
+			continue;
+
+		if (alloc_flags & ALLOC_WATERMARKS) {
+			if (!zone_watermark_ok(*z, order, (*z)->pages_low,
+				    classzone_idx, alloc_flags))
+				continue;
+		}
+
+		page = buffered_rmqueue(*z, order, gfp_mask);
+		if (page) {
+			zone_statistics(zonelist, *z);
+			break;
+		}
+		z++;
+	} while (*z != NULL);
+	return page;
 }
 
 /*

@@ -778,70 +808,49 @@ __alloc_pages(gfp_t gfp_mask, unsigned i
 		struct zonelist *zonelist)
 {
 	const int wait = gfp_mask & __GFP_WAIT;
-	struct zone **zones, *z;
+	struct zone **z;
 	struct page *page;
 	struct reclaim_state reclaim_state;
 	struct task_struct *p = current;
-	int i;
-	int classzone_idx;
 	int do_retry;
-	int can_try_harder;
+	int alloc_flags;
 	int did_some_progress;
 
 	might_sleep_if(wait);
 
-	/*
-	 * The caller may dip into page reserves a bit more if the caller
-	 * cannot run direct reclaim, or is the caller has realtime scheduling
-	 * policy
-	 */
-	can_try_harder = (unlikely(rt_task(p)) && !in_interrupt()) || !wait;
-
-	zones = zonelist->zones;  /* the list of zones suitable for gfp_mask */
+	z = zonelist->zones;  /* the list of zones suitable for gfp_mask */
 
-	if (unlikely(zones[0] == NULL)) {
+	if (unlikely(*z == NULL)) {
 		/* Should this ever happen?? */
 		return NULL;
 	}
+restart:
+	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
+				zonelist, ALLOC_WATERMARKS|ALLOC_CPUSET);
+	if (page)
+		goto got_pg;
 
-	classzone_idx = zone_idx(zones[0]);
+	do {
+		wakeup_kswapd(*z, order);
+		z++;
+	} while (*z != NULL);
 
-restart:
 	/*
-	 * Go through the zonelist once, looking for a zone with enough free.
-	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+	 * OK, we're below the kswapd watermark and have kicked background
+	 * reclaim. Now things get more complex, so st up alloc_flags according
+	 * to how we want to proceed.
+	 *
+	 * The caller may dip into page reserves a bit more if the caller
+	 * cannot run direct reclaim, or is the caller has realtime scheduling
+	 * policy.
 	 */
-	for (i = 0; (z = zones[i]) != NULL; i++) {
-		int do_reclaim = should_reclaim_zone(z, gfp_mask);
-
-		if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
-			continue;
-
-		/*
-		 * If the zone is to attempt early page reclaim then this loop
-		 * will try to reclaim pages and check the watermark a second
-		 * time before giving up and falling back to the next zone.
-		 */
-zone_reclaim_retry:
-		if (!zone_watermark_ok(z, order, z->pages_low,
-				       classzone_idx, 0, 0)) {
-			if (!do_reclaim)
-				continue;
-			else {
-				zone_reclaim(z, gfp_mask, order);
-				/* Only try reclaim once */
-				do_reclaim = 0;
-				goto zone_reclaim_retry;
-			}
-		}
-
-		page = buffered_rmqueue(z, order, gfp_mask);
-		if (page)
-			goto got_pg;
-	}
-
-	for (i = 0; (z = zones[i]) != NULL; i++)
-		wakeup_kswapd(z, order);
+	alloc_flags = 0;
+	if ((unlikely(rt_task(p)) && !in_interrupt()) || !wait)
+		alloc_flags |= ALLOC_HARDER;
+	if (gfp_mask & __GFP_HIGH)
+		alloc_flags |= ALLOC_HIGH;
+	if (wait)
+		alloc_flags |= ALLOC_CPUSET;
 
 	/*
 	 * Go through the zonelist again. Let __GFP_HIGH and allocations

@@ -851,19 +860,9 @@ zone_reclaim_retry:
 	 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
 	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
 	 */
-	for (i = 0; (z = zones[i]) != NULL; i++) {
-		if (!zone_watermark_ok(z, order, z->pages_min,
-				       classzone_idx, can_try_harder,
-				       gfp_mask & __GFP_HIGH))
-			continue;
-
-		if (wait && !cpuset_zone_allowed(z, gfp_mask))
-			continue;
-
-		page = buffered_rmqueue(z, order, gfp_mask);
-		if (page)
-			goto got_pg;
-	}
+	page = get_page_from_freelist(gfp_mask, order, zonelist, alloc_flags);
+	if (page)
+		goto got_pg;
 
 	/* This allocation should allow future memory freeing. */
 

@@ -871,13 +870,10 @@ zone_reclaim_retry:
 			&& !in_interrupt()) {
 		if (!(gfp_mask & __GFP_NOMEMALLOC)) {
 			/* go through the zonelist yet again, ignoring mins */
-			for (i = 0; (z = zones[i]) != NULL; i++) {
-				if (!cpuset_zone_allowed(z, gfp_mask))
-					continue;
-				page = buffered_rmqueue(z, order, gfp_mask);
-				if (page)
-					goto got_pg;
-			}
+			page = get_page_from_freelist(gfp_mask, order,
+						zonelist, ALLOC_CPUSET);
+			if (page)
+				goto got_pg;
 		}
 		goto nopage;
 	}

@@ -894,7 +890,7 @@ rebalance:
 	reclaim_state.reclaimed_slab = 0;
 	p->reclaim_state = &reclaim_state;
 
-	did_some_progress = try_to_free_pages(zones, gfp_mask);
+	did_some_progress = try_to_free_pages(zonelist->zones, gfp_mask);
 
 	p->reclaim_state = NULL;
 	p->flags &= ~PF_MEMALLOC;

@@ -902,19 +898,10 @@ rebalance:
 	cond_resched();
 
 	if (likely(did_some_progress)) {
-		for (i = 0; (z = zones[i]) != NULL; i++) {
-			if (!zone_watermark_ok(z, order, z->pages_min,
-					       classzone_idx, can_try_harder,
-					       gfp_mask & __GFP_HIGH))
-				continue;
-
-			if (!cpuset_zone_allowed(z, gfp_mask))
-				continue;
-
-			page = buffered_rmqueue(z, order, gfp_mask);
-			if (page)
-				goto got_pg;
-		}
+		page = get_page_from_freelist(gfp_mask, order,
+						zonelist, alloc_flags);
+		if (page)
+			goto got_pg;
 	} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
 		/*
 		 * Go through the zonelist yet one more time, keep

@@ -922,18 +909,10 @@ rebalance:
 		 * a parallel oom killing, we must fail if we're still
 		 * under heavy pressure.
 		 */
-		for (i = 0; (z = zones[i]) != NULL; i++) {
-			if (!zone_watermark_ok(z, order, z->pages_high,
-					       classzone_idx, 0, 0))
-				continue;
-
-			if (!cpuset_zone_allowed(z, __GFP_HARDWALL))
-				continue;
-
-			page = buffered_rmqueue(z, order, gfp_mask);
-			if (page)
-				goto got_pg;
-		}
+		page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, order,
+				zonelist, ALLOC_WATERMARKS|ALLOC_CPUSET);
+		if (page)
+			goto got_pg;
 
 		out_of_memory(gfp_mask, order);
 		goto restart;

@@ -966,9 +945,7 @@ nopage:
 		dump_stack();
 		show_mem();
 	}
-	return NULL;
 got_pg:
-	zone_statistics(zonelist, z);
 	return page;
 }
 

Index: linux-2.6/include/linux/mmzone.h
===================================================================
@@ -302,7 +302,7 @@ void get_zone_counts(unsigned long *acti
 void build_all_zonelists(void);
 void wakeup_kswapd(struct zone *zone, int order);
 int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
-		int alloc_type, int can_try_harder, int gfp_high);
+		int classzone_idx, int alloc_flags);
 
 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 void memory_present(int nid, unsigned long start, unsigned long end);

Index: linux-2.6/mm/vmscan.c
===================================================================
@@ -1069,7 +1069,7 @@ loop_again:
 
 			if (nr_pages == 0) {	/* Not software suspend */
 				if (zone_watermark_ok(zone, order,
-					zone->pages_high, first_low_zone, 0, 0))
+					zone->pages_high, first_low_zone, 0))
 					continue;
 
 				all_zones_ok = 0;

@@ -1222,7 +1222,7 @@ void wakeup_kswapd(struct zone *zone, in
 		return;
 
 	pgdat = zone->zone_pgdat;
-	if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0, 0))
+	if (zone_watermark_ok(zone, order, zone->pages_low, 0, 0))
 		return;
 	if (pgdat->kswapd_max_order < order)
 		pgdat->kswapd_max_order = order;

@@ -58,6 +58,7 @@ struct vm_area_struct;
 			__GFP_NOFAIL|__GFP_NORETRY|__GFP_NO_GROW|__GFP_COMP| \
 			__GFP_NOMEMALLOC|__GFP_HARDWALL)
 
+/* GFP_ATOMIC means both !wait (__GFP_WAIT not set) and use emergency pool */
 #define GFP_ATOMIC	(__GFP_VALID | __GFP_HIGH)
 #define GFP_NOIO	(__GFP_VALID | __GFP_WAIT)
 #define GFP_NOFS	(__GFP_VALID | __GFP_WAIT | __GFP_IO)