diff --git a/arch/powerpc/mm/hugetlbpage-radix.c b/arch/powerpc/mm/hugetlbpage-radix.c
index 558e9d3891bf..bd022d16745c 100644
--- a/arch/powerpc/mm/hugetlbpage-radix.c
+++ b/arch/powerpc/mm/hugetlbpage-radix.c
@@ -49,17 +49,28 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	struct hstate *h = hstate_file(file);
+	int fixed = (flags & MAP_FIXED);
+	unsigned long high_limit;
 	struct vm_unmapped_area_info info;
 
-	if (unlikely(addr > mm->context.addr_limit && addr < TASK_SIZE))
-		mm->context.addr_limit = TASK_SIZE;
+	high_limit = DEFAULT_MAP_WINDOW;
+	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
+		high_limit = TASK_SIZE;
 
 	if (len & ~huge_page_mask(h))
 		return -EINVAL;
-	if (len > mm->task_size)
+	if (len > high_limit)
 		return -ENOMEM;
+	if (fixed) {
+		if (addr > high_limit - len)
+			return -ENOMEM;
+	}
 
-	if (flags & MAP_FIXED) {
+	if (unlikely(addr > mm->context.addr_limit &&
+		     mm->context.addr_limit != TASK_SIZE))
+		mm->context.addr_limit = TASK_SIZE;
+
+	if (fixed) {
 		if (prepare_hugepage_range(file, addr, len))
 			return -EINVAL;
 		return addr;
@@ -68,7 +79,7 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	if (addr) {
 		addr = ALIGN(addr, huge_page_size(h));
 		vma = find_vma(mm, addr);
-		if (mm->task_size - len >= addr &&
+		if (high_limit - len >= addr &&
 		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
@@ -79,12 +90,9 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = PAGE_SIZE;
-	info.high_limit = current->mm->mmap_base;
+	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 	info.align_offset = 0;
 
-	if (addr > DEFAULT_MAP_WINDOW)
-		info.high_limit += mm->context.addr_limit - DEFAULT_MAP_WINDOW;
-
 	return vm_unmapped_area(&info);
 }
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c
index 5d78b193fec4..6d476a7b5611 100644
--- a/arch/powerpc/mm/mmap.c
+++ b/arch/powerpc/mm/mmap.c
@@ -106,22 +106,32 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
+	int fixed = (flags & MAP_FIXED);
+	unsigned long high_limit;
 	struct vm_unmapped_area_info info;
 
+	high_limit = DEFAULT_MAP_WINDOW;
+	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
+		high_limit = TASK_SIZE;
+
+	if (len > high_limit)
+		return -ENOMEM;
+	if (fixed) {
+		if (addr > high_limit - len)
+			return -ENOMEM;
+	}
+
 	if (unlikely(addr > mm->context.addr_limit &&
 		     mm->context.addr_limit != TASK_SIZE))
 		mm->context.addr_limit = TASK_SIZE;
 
-	if (len > mm->task_size - mmap_min_addr)
-		return -ENOMEM;
-
-	if (flags & MAP_FIXED)
+	if (fixed)
 		return addr;
 
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
+		if (high_limit - len >= addr && addr >= mmap_min_addr &&
 		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
@@ -129,13 +139,9 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.flags = 0;
 	info.length = len;
 	info.low_limit = mm->mmap_base;
+	info.high_limit = high_limit;
 	info.align_mask = 0;
 
-	if (unlikely(addr > DEFAULT_MAP_WINDOW))
-		info.high_limit = mm->context.addr_limit;
-	else
-		info.high_limit = DEFAULT_MAP_WINDOW;
-
 	return vm_unmapped_area(&info);
 }
 
@@ -149,37 +155,42 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
+	int fixed = (flags & MAP_FIXED);
+	unsigned long high_limit;
 	struct vm_unmapped_area_info info;
 
+	high_limit = DEFAULT_MAP_WINDOW;
+	if (addr >= high_limit || (fixed && (addr + len > high_limit)))
+		high_limit = TASK_SIZE;
+
+	if (len > high_limit)
+		return -ENOMEM;
+	if (fixed) {
+		if (addr > high_limit - len)
+			return -ENOMEM;
+	}
+
 	if (unlikely(addr > mm->context.addr_limit &&
 		     mm->context.addr_limit != TASK_SIZE))
 		mm->context.addr_limit = TASK_SIZE;
 
-	/* requested length too big for entire address space */
-	if (len > mm->task_size - mmap_min_addr)
-		return -ENOMEM;
-
-	if (flags & MAP_FIXED)
+	if (fixed)
 		return addr;
 
-	/* requesting a specific address */
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
-				(!vma || addr + len <= vm_start_gap(vma)))
+		if (high_limit - len >= addr && addr >= mmap_min_addr &&
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
 	info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 	info.length = len;
 	info.low_limit = max(PAGE_SIZE, mmap_min_addr);
-	info.high_limit = mm->mmap_base;
+	info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW);
 	info.align_mask = 0;
 
-	if (addr > DEFAULT_MAP_WINDOW)
-		info.high_limit += mm->context.addr_limit - DEFAULT_MAP_WINDOW;
-
 	addr = vm_unmapped_area(&info);
 	if (!(addr & ~PAGE_MASK))
 		return addr;
