30 files changed, 1836 insertions, 1052 deletions

diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index af7cfb43d2f..8b1a477162d 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -1,27 +1,24 @@
 config DEBUG_PAGEALLOC
 	bool "Debug page memory allocations"
-	depends on DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on !HIBERNATION || !PPC && !SPARC
+	depends on DEBUG_KERNEL
+	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
 	depends on !KMEMCHECK
+	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	---help---
 	  Unmap pages from the kernel linear mapping after free_pages().
 	  This results in a large slowdown, but helps to find certain types
 	  of memory corruption.
 
+	  For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
+	  fill the pages with poison patterns after free_pages() and verify
+	  the patterns before alloc_pages().  Additionally,
+	  this option cannot be enabled in combination with hibernation as
+	  that would result in incorrect warnings of memory corruption after
+	  a resume because free pages are not saved to the suspend image.
+
 config WANT_PAGE_DEBUG_FLAGS
 	bool
 
 config PAGE_POISONING
-	bool "Debug page memory allocations"
-	depends on DEBUG_KERNEL && !ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on !HIBERNATION
-	select DEBUG_PAGEALLOC
+	bool
 	select WANT_PAGE_DEBUG_FLAGS
-	---help---
-	   Fill the pages with poison patterns after free_pages() and verify
-	   the patterns before alloc_pages(). This results in a large slowdown,
-	   but helps to find certain types of memory corruption.
-
-	   This option cannot be enabled in combination with hibernation as
-	   that would result in incorrect warnings of memory corruption after
-	   a resume because free pages are not saved to the suspend image.
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 07aeb89e396..01d5a4b3dd0 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -34,14 +34,6 @@ unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
 
-#ifdef CONFIG_CRASH_DUMP
-/*
- * If we have booted due to a crash, max_pfn will be a very low value. We need
- * to know the amount of memory that the previous kernel used.
- */
-unsigned long saved_max_pfn;
-#endif
-
 bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
 
 static struct list_head bdata_list __initdata = LIST_HEAD_INIT(bdata_list);
diff --git a/mm/compaction.c b/mm/compaction.c
index 8be430b812d..021a2960ef9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -42,8 +42,6 @@ struct compact_control {
 	unsigned int order;		/* order a direct compactor needs */
 	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
 	struct zone *zone;
-
-	int compact_mode;
 };
 
 static unsigned long release_freepages(struct list_head *freelist)
@@ -155,7 +153,6 @@ static void isolate_freepages(struct zone *zone,
 	 * pages on cc->migratepages. We stop searching if the migrate
 	 * and free page scanners meet or enough free pages are isolated.
 	 */
-	spin_lock_irqsave(&zone->lock, flags);
 	for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
 					pfn -= pageblock_nr_pages) {
 		unsigned long isolated;
@@ -178,9 +175,19 @@ static void isolate_freepages(struct zone *zone,
 		if (!suitable_migration_target(page))
 			continue;
 
-		/* Found a block suitable for isolating free pages from */
-		isolated = isolate_freepages_block(zone, pfn, freelist);
-		nr_freepages += isolated;
+		/*
+		 * Found a block suitable for isolating free pages from. Now
+		 * we disabled interrupts, double check things are ok and
+		 * isolate the pages. This is to minimise the time IRQs
+		 * are disabled
+		 */
+		isolated = 0;
+		spin_lock_irqsave(&zone->lock, flags);
+		if (suitable_migration_target(page)) {
+			isolated = isolate_freepages_block(zone, pfn, freelist);
+			nr_freepages += isolated;
+		}
+		spin_unlock_irqrestore(&zone->lock, flags);
 
 		/*
 		 * Record the highest PFN we isolated pages from. When next
@@ -190,7 +197,6 @@ static void isolate_freepages(struct zone *zone,
 		if (isolated)
 			high_pfn = max(high_pfn, pfn);
 	}
-	spin_unlock_irqrestore(&zone->lock, flags);
 
 	/* split_free_page does not map the pages */
 	list_for_each_entry(page, freelist, lru) {
@@ -271,9 +277,27 @@ static unsigned long isolate_migratepages(struct zone *zone,
 	}
 
 	/* Time to isolate some pages for migration */
+	cond_resched();
 	spin_lock_irq(&zone->lru_lock);
 	for (; low_pfn < end_pfn; low_pfn++) {
 		struct page *page;
+		bool locked = true;
+
+		/* give a chance to irqs before checking need_resched() */
+		if (!((low_pfn+1) % SWAP_CLUSTER_MAX)) {
+			spin_unlock_irq(&zone->lru_lock);
+			locked = false;
+		}
+		if (need_resched() || spin_is_contended(&zone->lru_lock)) {
+			if (locked)
+				spin_unlock_irq(&zone->lru_lock);
+			cond_resched();
+			spin_lock_irq(&zone->lru_lock);
+			if (fatal_signal_pending(current))
+				break;
+		} else if (!locked)
+			spin_lock_irq(&zone->lru_lock);
+
 		if (!pfn_valid_within(low_pfn))
 			continue;
 		nr_scanned++;
@@ -397,10 +421,7 @@ static int compact_finished(struct zone *zone,
 		return COMPACT_COMPLETE;
 
 	/* Compaction run is not finished if the watermark is not met */
-	if (cc->compact_mode != COMPACT_MODE_KSWAPD)
-		watermark = low_wmark_pages(zone);
-	else
-		watermark = high_wmark_pages(zone);
+	watermark = low_wmark_pages(zone);
 	watermark += (1 << cc->order);
 
 	if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
@@ -413,15 +434,6 @@ static int compact_finished(struct zone *zone,
 	if (cc->order == -1)
 		return COMPACT_CONTINUE;
 
-	/*
-	 * Generating only one page of the right order is not enough
-	 * for kswapd, we must continue until we're above the high
-	 * watermark as a pool for high order GFP_ATOMIC allocations
-	 * too.
-	 */
-	if (cc->compact_mode == COMPACT_MODE_KSWAPD)
-		return COMPACT_CONTINUE;
-
 	/* Direct compactor: Is a suitable page free? */
 	for (order = cc->order; order < MAX_ORDER; order++) {
 		/* Job done if page is free of the right migratetype */
@@ -508,12 +520,13 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 
 	while ((ret = compact_finished(zone, cc)) == COMPACT_CONTINUE) {
 		unsigned long nr_migrate, nr_remaining;
+		int err;
 
 		if (!isolate_migratepages(zone, cc))
 			continue;
 
 		nr_migrate = cc->nr_migratepages;
-		migrate_pages(&cc->migratepages, compaction_alloc,
+		err = migrate_pages(&cc->migratepages, compaction_alloc,
 				(unsigned long)cc, false,
 				cc->sync);
 		update_nr_listpages(cc);
@@ -527,7 +540,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 						nr_remaining);
 
 		/* Release LRU pages not migrated */
-		if (!list_empty(&cc->migratepages)) {
+		if (err) {
 			putback_lru_pages(&cc->migratepages);
 			cc->nr_migratepages = 0;
 		}
@@ -543,8 +556,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 
 unsigned long compact_zone_order(struct zone *zone,
 				 int order, gfp_t gfp_mask,
-				 bool sync,
-				 int compact_mode)
+				 bool sync)
 {
 	struct compact_control cc = {
 		.nr_freepages = 0,
@@ -553,7 +565,6 @@ unsigned long compact_zone_order(struct zone *zone,
 		.migratetype = allocflags_to_migratetype(gfp_mask),
 		.zone = zone,
 		.sync = sync,
-		.compact_mode = compact_mode,
 	};
 	INIT_LIST_HEAD(&cc.freepages);
 	INIT_LIST_HEAD(&cc.migratepages);
@@ -599,8 +610,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist,
 								nodemask) {
 		int status;
 
-		status = compact_zone_order(zone, order, gfp_mask, sync,
-					    COMPACT_MODE_DIRECT_RECLAIM);
+		status = compact_zone_order(zone, order, gfp_mask, sync);
 		rc = max(status, rc);
 
 		/* If a normal allocation would succeed, stop compacting */
@@ -631,7 +641,6 @@ static int compact_node(int nid)
 			.nr_freepages = 0,
 			.nr_migratepages = 0,
 			.order = -1,
-			.compact_mode = COMPACT_MODE_DIRECT_RECLAIM,
 		};
 
 		zone = &pgdat->node_zones[zoneid];
diff --git a/mm/filemap.c b/mm/filemap.c
index 83a45d35468..f807afda86f 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -108,11 +108,11 @@
  */
 
 /*
- * Remove a page from the page cache and free it. Caller has to make
+ * Delete a page from the page cache and free it. Caller has to make
  * sure the page is locked and that nobody else uses it - or that usage
  * is safe.  The caller must hold the mapping's tree_lock.
  */
-void __remove_from_page_cache(struct page *page)
+void __delete_from_page_cache(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 
@@ -137,7 +137,15 @@ void __remove_from_page_cache(struct page *page)
 	}
 }
 
-void remove_from_page_cache(struct page *page)
+/**
+ * delete_from_page_cache - delete page from page cache
+ * @page: the page which the kernel is trying to remove from page cache
+ *
+ * This must be called only on pages that have been verified to be in the page
+ * cache and locked.  It will never put the page into the free list, the caller
+ * has a reference on the page.
+ */
+void delete_from_page_cache(struct page *page)
 {
 	struct address_space *mapping = page->mapping;
 	void (*freepage)(struct page *);
@@ -146,14 +154,15 @@ void remove_from_page_cache(struct page *page)
 
 	freepage = mapping->a_ops->freepage;
 	spin_lock_irq(&mapping->tree_lock);
-	__remove_from_page_cache(page);
+	__delete_from_page_cache(page);
 	spin_unlock_irq(&mapping->tree_lock);
 	mem_cgroup_uncharge_cache_page(page);
 
 	if (freepage)
 		freepage(page);
+	page_cache_release(page);
 }
-EXPORT_SYMBOL(remove_from_page_cache);
+EXPORT_SYMBOL(delete_from_page_cache);
 
 static int sync_page(void *word)
 {
@@ -387,6 +396,76 @@ int filemap_write_and_wait_range(struct address_space *mapping,
 EXPORT_SYMBOL(filemap_write_and_wait_range);
 
 /**
+ * replace_page_cache_page - replace a pagecache page with a new one
+ * @old:	page to be replaced
+ * @new:	page to replace with
+ * @gfp_mask:	allocation mode
+ *
+ * This function replaces a page in the pagecache with a new one.  On
+ * success it acquires the pagecache reference for the new page and
+ * drops it for the old page.  Both the old and new pages must be
+ * locked.  This function does not add the new page to the LRU, the
+ * caller must do that.
+ *
+ * The remove + add is atomic.  The only way this function can fail is
+ * memory allocation failure.
+ */
+int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
+{
+	int error;
+	struct mem_cgroup *memcg = NULL;
+
+	VM_BUG_ON(!PageLocked(old));
+	VM_BUG_ON(!PageLocked(new));
+	VM_BUG_ON(new->mapping);
+
+	/*
+	 * This is not page migration, but prepare_migration and
+	 * end_migration does enough work for charge replacement.
+	 *
+	 * In the longer term we probably want a specialized function
+	 * for moving the charge from old to new in a more efficient
+	 * manner.
+	 */
+	error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask);
+	if (error)
+		return error;
+
+	error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
+	if (!error) {
+		struct address_space *mapping = old->mapping;
+		void (*freepage)(struct page *);
+
+		pgoff_t offset = old->index;
+		freepage = mapping->a_ops->freepage;
+
+		page_cache_get(new);
+		new->mapping = mapping;
+		new->index = offset;
+
+		spin_lock_irq(&mapping->tree_lock);
+		__delete_from_page_cache(old);
+		error = radix_tree_insert(&mapping->page_tree, offset, new);
+		BUG_ON(error);
+		mapping->nrpages++;
+		__inc_zone_page_state(new, NR_FILE_PAGES);
+		if (PageSwapBacked(new))
+			__inc_zone_page_state(new, NR_SHMEM);
+		spin_unlock_irq(&mapping->tree_lock);
+		radix_tree_preload_end();
+		if (freepage)
+			freepage(old);
+		page_cache_release(old);
+		mem_cgroup_end_migration(memcg, old, new, true);
+	} else {
+		mem_cgroup_end_migration(memcg, old, new, false);
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(replace_page_cache_page);
+
+/**
  * add_to_page_cache_locked - add a locked page to the pagecache
  * @page:	page to add
  * @mapping:	the page's address_space
@@ -621,8 +700,10 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 		__lock_page(page);
 		return 1;
 	} else {
-		up_read(&mm->mmap_sem);
-		wait_on_page_locked(page);
+		if (!(flags & FAULT_FLAG_RETRY_NOWAIT)) {
+			up_read(&mm->mmap_sem);
+			wait_on_page_locked(page);
+		}
 		return 0;
 	}
 }
@@ -782,9 +863,13 @@ repeat:
 		page = radix_tree_deref_slot((void **)pages[i]);
 		if (unlikely(!page))
 			continue;
+
+		/*
+		 * This can only trigger when the entry at index 0 moves out
+		 * of or back to the root: none yet gotten, safe to restart.
+		 */
 		if (radix_tree_deref_retry(page)) {
-			if (ret)
-				start = pages[ret-1]->index;
+			WARN_ON(start | i);
 			goto restart;
 		}
 
@@ -800,6 +885,13 @@ repeat:
 		pages[ret] = page;
 		ret++;
 	}
+
+	/*
+	 * If all entries were removed before we could secure them,
+	 * try again, because callers stop trying once 0 is returned.
+	 */
+	if (unlikely(!ret && nr_found))
+		goto restart;
 	rcu_read_unlock();
 	return ret;
 }
@@ -834,6 +926,11 @@ repeat:
 		page = radix_tree_deref_slot((void **)pages[i]);
 		if (unlikely(!page))
 			continue;
+
+		/*
+		 * This can only trigger when the entry at index 0 moves out
+		 * of or back to the root: none yet gotten, safe to restart.
+		 */
 		if (radix_tree_deref_retry(page))
 			goto restart;
 
@@ -894,6 +991,11 @@ repeat:
 		page = radix_tree_deref_slot((void **)pages[i]);
 		if (unlikely(!page))
 			continue;
+
+		/*
+		 * This can only trigger when the entry at index 0 moves out
+		 * of or back to the root: none yet gotten, safe to restart.
+		 */
 		if (radix_tree_deref_retry(page))
 			goto restart;
 
@@ -909,6 +1011,13 @@ repeat:
 		pages[ret] = page;
 		ret++;
 	}
+
+	/*
+	 * If all entries were removed before we could secure them,
+	 * try again, because callers stop trying once 0 is returned.
+	 */
+	if (unlikely(!ret && nr_found))
+		goto restart;
 	rcu_read_unlock();
 
 	if (ret)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 113e35c4750..0a619e0e2e0 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -643,23 +643,24 @@ static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
 	return ret;
 }
 
-static inline gfp_t alloc_hugepage_gfpmask(int defrag)
+static inline gfp_t alloc_hugepage_gfpmask(int defrag, gfp_t extra_gfp)
 {
-	return GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT);
+	return (GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT)) | extra_gfp;
 }
 
 static inline struct page *alloc_hugepage_vma(int defrag,
 					      struct vm_area_struct *vma,
-					      unsigned long haddr, int nd)
+					      unsigned long haddr, int nd,
+					      gfp_t extra_gfp)
 {
-	return alloc_pages_vma(alloc_hugepage_gfpmask(defrag),
+	return alloc_pages_vma(alloc_hugepage_gfpmask(defrag, extra_gfp),
 			       HPAGE_PMD_ORDER, vma, haddr, nd);
 }
 
 #ifndef CONFIG_NUMA
 static inline struct page *alloc_hugepage(int defrag)
 {
-	return alloc_pages(alloc_hugepage_gfpmask(defrag),
+	return alloc_pages(alloc_hugepage_gfpmask(defrag, 0),
 			   HPAGE_PMD_ORDER);
 }
 #endif
@@ -678,7 +679,7 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		if (unlikely(khugepaged_enter(vma)))
 			return VM_FAULT_OOM;
 		page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
-					  vma, haddr, numa_node_id());
+					  vma, haddr, numa_node_id(), 0);
 		if (unlikely(!page))
 			goto out;
 		if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
@@ -799,7 +800,8 @@ static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
 	}
 
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
-		pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE,
+		pages[i] = alloc_page_vma_node(GFP_HIGHUSER_MOVABLE |
+					       __GFP_OTHER_NODE,
 					       vma, address, page_to_nid(page));
 		if (unlikely(!pages[i] ||
 			     mem_cgroup_newpage_charge(pages[i], mm,
@@ -902,7 +904,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	if (transparent_hugepage_enabled(vma) &&
 	    !transparent_hugepage_debug_cow())
 		new_page = alloc_hugepage_vma(transparent_hugepage_defrag(vma),
-					      vma, haddr, numa_node_id());
+					      vma, haddr, numa_node_id(), 0);
 	else
 		new_page = NULL;
 
@@ -1779,7 +1781,7 @@ static void collapse_huge_page(struct mm_struct *mm,
 	 * scalability.
 	 */
 	new_page = alloc_hugepage_vma(khugepaged_defrag(), vma, address,
-				      node);
+				      node, __GFP_OTHER_NODE);
 	if (unlikely(!new_page)) {
 		up_read(&mm->mmap_sem);
 		*hpage = ERR_PTR(-ENOMEM);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bb0b7c12801..06de5aa4d64 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1872,8 +1872,7 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy,
 	unsigned long tmp;
 	int ret;
 
-	if (!write)
-		tmp = h->max_huge_pages;
+	tmp = h->max_huge_pages;
 
 	if (write && h->order >= MAX_ORDER)
 		return -EINVAL;
@@ -1938,8 +1937,7 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
 	unsigned long tmp;
 	int ret;
 
-	if (!write)
-		tmp = h->nr_overcommit_huge_pages;
+	tmp = h->nr_overcommit_huge_pages;
 
 	if (write && h->order >= MAX_ORDER)
 		return -EINVAL;
diff --git a/mm/ksm.c b/mm/ksm.c
index c2b2a94f9d6..1bbe785aa55 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -301,20 +301,6 @@ static inline int in_stable_tree(struct rmap_item *rmap_item)
 	return rmap_item->address & STABLE_FLAG;
 }
 
-static void hold_anon_vma(struct rmap_item *rmap_item,
-			  struct anon_vma *anon_vma)
-{
-	rmap_item->anon_vma = anon_vma;
-	get_anon_vma(anon_vma);
-}
-
-static void ksm_drop_anon_vma(struct rmap_item *rmap_item)
-{
-	struct anon_vma *anon_vma = rmap_item->anon_vma;
-
-	drop_anon_vma(anon_vma);
-}
-
 /*
  * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's
  * page tables after it has passed through ksm_exit() - which, if necessary,
@@ -397,7 +383,7 @@ static void break_cow(struct rmap_item *rmap_item)
 	 * It is not an accident that whenever we want to break COW
 	 * to undo, we also need to drop a reference to the anon_vma.
 	 */
-	ksm_drop_anon_vma(rmap_item);
+	put_anon_vma(rmap_item->anon_vma);
 
 	down_read(&mm->mmap_sem);
 	if (ksm_test_exit(mm))
@@ -466,7 +452,7 @@ static void remove_node_from_stable_tree(struct stable_node *stable_node)
 			ksm_pages_sharing--;
 		else
 			ksm_pages_shared--;
-		ksm_drop_anon_vma(rmap_item);
+		put_anon_vma(rmap_item->anon_vma);
 		rmap_item->address &= PAGE_MASK;
 		cond_resched();
 	}
@@ -554,7 +540,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
 		else
 			ksm_pages_shared--;
 
-		ksm_drop_anon_vma(rmap_item);
+		put_anon_vma(rmap_item->anon_vma);
 		rmap_item->address &= PAGE_MASK;
 
 	} else if (rmap_item->address & UNSTABLE_FLAG) {
@@ -949,7 +935,8 @@ static int try_to_merge_with_ksm_page(struct rmap_item *rmap_item,
 		goto out;
 
 	/* Must get reference to anon_vma while still holding mmap_sem */
-	hold_anon_vma(rmap_item, vma->anon_vma);
+	rmap_item->anon_vma = vma->anon_vma;
+	get_anon_vma(vma->anon_vma);
 out:
 	up_read(&mm->mmap_sem);
 	return err;
diff --git a/mm/memblock.c b/mm/memblock.c
index 4618fda975a..a0562d1a6ad 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -58,28 +58,6 @@ static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, p
 	return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
 }
 
-static long __init_memblock memblock_addrs_adjacent(phys_addr_t base1, phys_addr_t size1,
-			       phys_addr_t base2, phys_addr_t size2)
-{
-	if (base2 == base1 + size1)
-		return 1;
-	else if (base1 == base2 + size2)
-		return -1;
-
-	return 0;
-}
-
-static long __init_memblock memblock_regions_adjacent(struct memblock_type *type,
-				 unsigned long r1, unsigned long r2)
-{
-	phys_addr_t base1 = type->regions[r1].base;
-	phys_addr_t size1 = type->regions[r1].size;
-	phys_addr_t base2 = type->regions[r2].base;
-	phys_addr_t size2 = type->regions[r2].size;
-
-	return memblock_addrs_adjacent(base1, size1, base2, size2);
-}
-
 long __init_memblock memblock_overlaps_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
 {
 	unsigned long i;
@@ -206,14 +184,13 @@ static void __init_memblock memblock_remove_region(struct memblock_type *type, u
 		type->regions[i].size = type->regions[i + 1].size;
 	}
 	type->cnt--;
-}
 
-/* Assumption: base addr of region 1 < base addr of region 2 */
-static void __init_memblock memblock_coalesce_regions(struct memblock_type *type,
-		unsigned long r1, unsigned long r2)
-{
-	type->regions[r1].size += type->regions[r2].size;
-	memblock_remove_region(type, r2);
+	/* Special case for empty arrays */
+	if (type->cnt == 0) {
+		type->cnt = 1;
+		type->regions[0].base = 0;
+		type->regions[0].size = 0;
+	}
 }
 
 /* Defined below but needed now */
@@ -276,7 +253,7 @@ static int __init_memblock memblock_double_array(struct memblock_type *type)
 		return 0;
 
 	/* Add the new reserved region now. Should not fail ! */
-	BUG_ON(memblock_add_region(&memblock.reserved, addr, new_size) < 0);
+	BUG_ON(memblock_add_region(&memblock.reserved, addr, new_size));
 
 	/* If the array wasn't our static init one, then free it. We only do
 	 * that before SLAB is available as later on, we don't know whether
@@ -296,58 +273,99 @@ extern int __init_memblock __weak memblock_memory_can_coalesce(phys_addr_t addr1
 	return 1;
 }
 
-static long __init_memblock memblock_add_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
+static long __init_memblock memblock_add_region(struct memblock_type *type,
+						phys_addr_t base, phys_addr_t size)
 {
-	unsigned long coalesced = 0;
-	long adjacent, i;
-
-	if ((type->cnt == 1) && (type->regions[0].size == 0)) {
-		type->regions[0].base = base;
-		type->regions[0].size = size;
-		return 0;
-	}
+	phys_addr_t end = base + size;
+	int i, slot = -1;
 
-	/* First try and coalesce this MEMBLOCK with another. */
+	/* First try and coalesce this MEMBLOCK with others */
 	for (i = 0; i < type->cnt; i++) {
-		phys_addr_t rgnbase = type->regions[i].base;
-		phys_addr_t rgnsize = type->regions[i].size;
+		struct memblock_region *rgn = &type->regions[i];
+		phys_addr_t rend = rgn->base + rgn->size;
+
+		/* Exit if there's no possible hits */
+		if (rgn->base > end || rgn->size == 0)
+			break;
 
-		if ((rgnbase == base) && (rgnsize == size))
-			/* Already have this region, so we're done */
+		/* Check if we are fully enclosed within an existing
+		 * block
+		 */
+		if (rgn->base <= base && rend >= end)
 			return 0;
 
-		adjacent = memblock_addrs_adjacent(base, size, rgnbase, rgnsize);
-		/* Check if arch allows coalescing */
-		if (adjacent != 0 && type == &memblock.memory &&
-		    !memblock_memory_can_coalesce(base, size, rgnbase, rgnsize))
-			break;
-		if (adjacent > 0) {
-			type->regions[i].base -= size;
-			type->regions[i].size += size;
-			coalesced++;
-			break;
-		} else if (adjacent < 0) {
-			type->regions[i].size += size;
-			coalesced++;
-			break;
+		/* Check if we overlap or are adjacent with the bottom
+		 * of a block.
+		 */
+		if (base < rgn->base && end >= rgn->base) {
+			/* If we can't coalesce, create a new block */
+			if (!memblock_memory_can_coalesce(base, size,
+							  rgn->base,
+							  rgn->size)) {
+				/* Overlap & can't coalesce are mutually
+				 * exclusive, if you do that, be prepared
+				 * for trouble
+				 */
+				WARN_ON(end != rgn->base);
+				goto new_block;
+			}
+			/* We extend the bottom of the block down to our
+			 * base
+			 */
+			rgn->base = base;
+			rgn->size = rend - base;
+
+			/* Return if we have nothing else to allocate
+			 * (fully coalesced)
+			 */
+			if (rend >= end)
+				return 0;
+
+			/* We continue processing from the end of the
+			 * coalesced block.
+			 */
+			base = rend;
+			size = end - base;
+		}
+
+		/* Now check if we overlap or are adjacent with the
+		 * top of a block
+		 */
+		if (base <= rend && end >= rend) {
+			/* If we can't coalesce, create a new block */
+			if (!memblock_memory_can_coalesce(rgn->base,
+							  rgn->size,
+							  base, size)) {
+				/* Overlap & can't coalesce are mutually
+				 * exclusive, if you do that, be prepared
+				 * for trouble
+				 */
+				WARN_ON(rend != base);
+				goto new_block;
+			}
+			/* We adjust our base down to enclose the
+			 * original block and destroy it. It will be
+			 * part of our new allocation. Since we've
+			 * freed an entry, we know we won't fail
+			 * to allocate one later, so we won't risk
+			 * losing the original block allocation.
+			 */
+			size += (base - rgn->base);
+			base = rgn->base;
+			memblock_remove_region(type, i--);
 		}
 	}
 
-	/* If we plugged a hole, we may want to also coalesce with the
-	 * next region
+	/* If the array is empty, special case, replace the fake
+	 * filler region and return
 	 */
-	if ((i < type->cnt - 1) && memblock_regions_adjacent(type, i, i+1) &&
-	    ((type != &memblock.memory || memblock_memory_can_coalesce(type->regions[i].base,
-							     type->regions[i].size,
-							     type->regions[i+1].base,
-							     type->regions[i+1].size)))) {
-		memblock_coalesce_regions(type, i, i+1);
-		coalesced++;
+	if ((type->cnt == 1) && (type->regions[0].size == 0)) {
+		type->regions[0].base = base;
+		type->regions[0].size = size;
+		return 0;
 	}
 
-	if (coalesced)
-		return coalesced;
-
+ new_block:
 	/* If we are out of space, we fail. It's too late to resize the array
 	 * but then this shouldn't have happened in the first place.
 	 */
@@ -362,13 +380,14 @@ static long __init_memblock memblock_add_region(struct memblock_type *type, phys
 		} else {
 			type->regions[i+1].base = base;
 			type->regions[i+1].size = size;
+			slot = i + 1;
 			break;
 		}
 	}
-
 	if (base < type->regions[0].base) {
 		type->regions[0].base = base;
 		type->regions[0].size = size;
+		slot = 0;
 	}
 	type->cnt++;
 
@@ -376,7 +395,8 @@ static long __init_memblock memblock_add_region(struct memblock_type *type, phys
 	 * our allocation and return an error
 	 */
 	if (type->cnt == type->max && memblock_double_array(type)) {
-		type->cnt--;
+		BUG_ON(slot < 0);
+		memblock_remove_region(type, slot);
 		return -1;
 	}
 
@@ -389,52 +409,55 @@ long __init_memblock memblock_add(phys_addr_t base, phys_addr_t size)
 
 }
 
-static long __init_memblock __memblock_remove(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
+static long __init_memblock __memblock_remove(struct memblock_type *type,
+					      phys_addr_t base, phys_addr_t size)
 {
-	phys_addr_t rgnbegin, rgnend;
 	phys_addr_t end = base + size;
 	int i;
 
-	rgnbegin = rgnend = 0; /* supress gcc warnings */
-
-	/* Find the region where (base, size) belongs to */
-	for (i=0; i < type->cnt; i++) {
-		rgnbegin = type->r