diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index ecc11482506e..2ac007a726dc 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2550,6 +2550,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 	spia_pedr=
 	spia_peddr=
 
+	stack_guard_gap=	[MM]
+			override the default stack gap protection. The value
+			is in page units and it defines how many pages prior
+			to (for stacks growing down) resp. after (for stacks
+			growing up) the main stack are reserved for no other
+			mapping. Default value is 256 pages.
+
 	stacktrace	[FTRACE]
 			Enabled the stack tracer on boot up.
 
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 49ee3193477a..16f903f19980 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1146,7 +1146,7 @@ arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
 		/* At this point:  (!vma || addr < vma->vm_end). */
 		if (limit - len < addr)
 			return -ENOMEM;
-		if (!vma || addr + len <= vma->vm_start)
+		if (!vma || addr + len <= vm_start_gap(vma))
 			return addr;
 		addr = vma->vm_end;
 		vma = vma->vm_next;
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index a26960a562ac..fcacb87ff104 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -69,7 +69,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 	int do_align = 0;
 	int aliasing = cache_is_vipt_aliasing();
 
@@ -101,7 +101,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 	if (len > mm->cached_hole_size) {
@@ -131,15 +131,17 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 		addr = vma->vm_end;
 		if (do_align)
 			addr = COLOUR_ALIGN(addr, pgoff);
diff --git a/arch/frv/mm/elf-fdpic.c b/arch/frv/mm/elf-fdpic.c
index 385fd30b142f..96eca58b9679 100644
--- a/arch/frv/mm/elf-fdpic.c
+++ b/arch/frv/mm/elf-fdpic.c
@@ -74,7 +74,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(current->mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			goto success;
 	}
 
@@ -89,7 +89,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 			for (; vma; vma = vma->vm_next) {
 				if (addr > limit)
 					break;
-				if (addr + len <= vma->vm_start)
+				if (addr + len <= vm_start_gap(vma))
 					goto success;
 				addr = vma->vm_end;
 			}
@@ -104,7 +104,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 		for (; vma; vma = vma->vm_next) {
 			if (addr > limit)
 				break;
-			if (addr + len <= vma->vm_start)
+			if (addr + len <= vm_start_gap(vma))
 				goto success;
 			addr = vma->vm_end;
 		}
diff --git a/arch/ia64/kernel/sys_ia64.c b/arch/ia64/kernel/sys_ia64.c
index 609d50056a6c..77c0aff5aaf0 100644
--- a/arch/ia64/kernel/sys_ia64.c
+++ b/arch/ia64/kernel/sys_ia64.c
@@ -27,7 +27,8 @@ arch_get_unmapped_area (struct file *filp, unsigned long addr, unsigned long len
 	long map_shared = (flags & MAP_SHARED);
 	unsigned long start_addr, align_mask = PAGE_SIZE - 1;
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma, *prev;
+	unsigned long prev_end;
 
 	if (len > RGN_MAP_LIMIT)
 		return -ENOMEM;
@@ -58,7 +59,17 @@ arch_get_unmapped_area (struct file *filp, unsigned long addr, unsigned long len
   full_search:
 	start_addr = addr = (addr + align_mask) & ~align_mask;
 
-	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+	for (vma = find_vma_prev(mm, addr, &prev); ; prev = vma,
+						vma = vma->vm_next) {
+		if (prev) {
+			prev_end = vm_end_gap(prev);
+			if (addr < prev_end) {
+				addr = (prev_end + align_mask) & ~align_mask;
+				/* If vma already violates gap, forget it */
+				if (vma && addr > vma->vm_start)
+					addr = vma->vm_start;
+			}
+		}
 		/* At this point:  (!vma || addr < vma->vm_end). */
 		if (TASK_SIZE - len < addr || RGN_MAP_LIMIT - len < REGION_OFFSET(addr)) {
 			if (start_addr != TASK_UNMAPPED_BASE) {
@@ -68,12 +79,11 @@ arch_get_unmapped_area (struct file *filp, unsigned long addr, unsigned long len
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (!vma || addr + len <= vm_start_gap(vma)) {
 			/* Remember the address where we stopped this search:  */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		addr = (vma->vm_end + align_mask) & ~align_mask;
 	}
 }
 
diff --git a/arch/ia64/mm/hugetlbpage.c b/arch/ia64/mm/hugetlbpage.c
index 5ca674b74737..66a1ec0a2467 100644
--- a/arch/ia64/mm/hugetlbpage.c
+++ b/arch/ia64/mm/hugetlbpage.c
@@ -171,9 +171,9 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, u
 		/* At this point:  (!vmm || addr < vmm->vm_end). */
 		if (REGION_OFFSET(addr) + len > RGN_MAP_LIMIT)
 			return -ENOMEM;
-		if (!vmm || (addr + len) <= vmm->vm_start)
+		if (!vmm || (addr + len) <= vm_start_gap(vmm))
 			return addr;
-		addr = ALIGN(vmm->vm_end, HPAGE_SIZE);
+		addr = ALIGN(vm_end_gap(vmm), HPAGE_SIZE);
 	}
 }
 
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index 302d779d5b0d..a79ddcfec1c7 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -70,6 +70,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned long addr = addr0;
+	unsigned long vm_start;
 	int do_color_align;
 
 	if (unlikely(len > TASK_SIZE))
@@ -103,7 +104,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -118,7 +119,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 			/* At this point:  (!vma || addr < vma->vm_end). */
 			if (TASK_SIZE - len < addr)
 				return -ENOMEM;
-			if (!vma || addr + len <= vma->vm_start)
+			if (!vma || addr + len <= vm_start_gap(vma))
 				return addr;
 			addr = vma->vm_end;
 			if (do_color_align)
@@ -145,7 +146,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 		/* make sure it can fit in the remaining address space */
 		if (likely(addr > len)) {
 			vma = find_vma(mm, addr - len);
-			if (!vma || addr <= vma->vm_start) {
+			if (!vma || addr <= vm_start_gap(vma)) {
 				/* cache the address as a hint for next time */
 				return mm->free_area_cache = addr - len;
 			}
@@ -165,20 +166,22 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
 			 * return with success:
 			 */
 			vma = find_vma(mm, addr);
-			if (likely(!vma || addr + len <= vma->vm_start)) {
+			if (vma)
+				vm_start = vm_start_gap(vma);
+			if (likely(!vma || addr + len <= vm_start)) {
 				/* cache the address as a hint for next time */
 				return mm->free_area_cache = addr;
 			}
 
 			/* remember the largest hole we saw so far */
-			if (addr + mm->cached_hole_size < vma->vm_start)
-				mm->cached_hole_size = vma->vm_start - addr;
+			if (addr + mm->cached_hole_size < vm_start)
+				mm->cached_hole_size = vm_start - addr;
 
 			/* try just below the current vma->vm_start */
-			addr = vma->vm_start - len;
+			addr = vm_start - len;
 			if (do_color_align)
 				addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-		} while (likely(len < vma->vm_start));
+		} while (likely(len < vm_start));
 
 bottomup:
 		/*
diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index c9b932260f47..0bb0ac47e855 100644
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -35,17 +35,27 @@
 
 static unsigned long get_unshared_area(unsigned long addr, unsigned long len)
 {
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma, *prev;
+	unsigned long prev_end;
 
 	addr = PAGE_ALIGN(addr);
 
-	for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
+	for (vma = find_vma_prev(current->mm, addr, &prev); ; prev = vma,
+							vma = vma->vm_next) {
+		if (prev) {
+			prev_end = vm_end_gap(prev);
+			if (addr < prev_end) {
+				addr = prev_end;
+				/* If vma already violates gap, forget it */
+				if (vma && addr > vma->vm_start)
+					addr = vma->vm_start;
+			}
+		}
 		/* At this point:  (!vma || addr < vma->vm_end). */
 		if (TASK_SIZE - len < addr)
 			return -ENOMEM;
-		if (!vma || addr + len <= vma->vm_start)
+		if (!vma || addr + len <= vm_start_gap(vma))
 			return addr;
-		addr = vma->vm_end;
 	}
 }
 
@@ -70,20 +80,30 @@ static int get_offset(struct address_space *mapping)
 static unsigned long get_shared_area(struct address_space *mapping,
 		unsigned long addr, unsigned long len, unsigned long pgoff)
 {
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma, *prev;
+	unsigned long prev_end;
 	int offset = mapping ? get_offset(mapping) : 0;
 
 	addr = DCACHE_ALIGN(addr - offset) + offset;
 
-	for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
+	for (vma = find_vma_prev(current->mm, addr, &prev); ; prev = vma,
+							vma = vma->vm_next) {
+		if (prev) {
+			prev_end = vm_end_gap(prev);
+			if (addr < prev_end) {
+				addr = DCACHE_ALIGN(prev_end - offset) + offset;
+				if (addr < prev_end)	/* handle wraparound */
+					return -ENOMEM;
+				/* If vma already violates gap, forget it */
+				if (vma && addr > vma->vm_start)
+					addr = vma->vm_start;
+			}
+		}
 		/* At this point:  (!vma || addr < vma->vm_end). */
 		if (TASK_SIZE - len < addr)
 			return -ENOMEM;
-		if (!vma || addr + len <= vma->vm_start)
+		if (!vma || addr + len <= vm_start_gap(vma))
 			return addr;
-		addr = DCACHE_ALIGN(vma->vm_end - offset) + offset;
-		if (addr < vma->vm_end) /* handle wraparound */
-			return -ENOMEM;
 	}
 }
 
diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
index 73709f7ce92c..57654c9b70f8 100644
--- a/arch/powerpc/mm/slice.c
+++ b/arch/powerpc/mm/slice.c
@@ -98,7 +98,7 @@ static int slice_area_is_free(struct mm_struct *mm, unsigned long addr,
 	if ((mm->task_size - len) < addr)
 		return 0;
 	vma = find_vma(mm, addr);
-	return (!vma || (addr + len) <= vma->vm_start);
+	return (!vma || (addr + len) <= vm_start_gap(vma));
 }
 
 static int slice_low_has_vma(struct mm_struct *mm, unsigned long slice)
@@ -227,7 +227,7 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 					      int psize, int use_cache)
 {
 	struct vm_area_struct *vma;
-	unsigned long start_addr, addr;
+	unsigned long start_addr, addr, vm_start;
 	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
 
@@ -256,7 +256,9 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 				addr = _ALIGN_UP(addr + 1,  1ul << SLICE_HIGH_SHIFT);
 			continue;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
@@ -264,8 +266,8 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 				mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (use_cache && (addr + mm->cached_hole_size) < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 		addr = vma->vm_end;
 	}
 
@@ -284,7 +286,7 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 					     int psize, int use_cache)
 {
 	struct vm_area_struct *vma;
-	unsigned long addr;
+	unsigned long addr, vm_start;
 	struct slice_mask mask;
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
 
@@ -336,7 +338,9 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
-		if (!vma || (addr + len) <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || (addr + len) <= vm_start) {
 			/* remember the address as a hint for next time */
 			if (use_cache)
 				mm->free_area_cache = addr;
@@ -344,11 +348,11 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 		}
 
 		/* remember the largest hole we saw so far */
-		if (use_cache && (addr + mm->cached_hole_size) < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (use_cache && (addr + mm->cached_hole_size) < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = vma->vm_start;
+		addr = vm_start;
 	}
 
 	/*
diff --git a/arch/sh/mm/mmap.c b/arch/sh/mm/mmap.c
index afeb710ec5c3..22eff46d8ef5 100644
--- a/arch/sh/mm/mmap.c
+++ b/arch/sh/mm/mmap.c
@@ -47,7 +47,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 	int do_colour_align;
 
 	if (flags & MAP_FIXED) {
@@ -75,7 +75,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -106,15 +106,17 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			}
 			return -ENOMEM;
 		}
-		if (likely(!vma || addr + len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		addr = vma->vm_end;
 		if (do_colour_align)
@@ -130,6 +132,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
+	unsigned long vm_start;
 	int do_colour_align;
 
 	if (flags & MAP_FIXED) {
@@ -158,7 +161,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -179,7 +182,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	/* make sure it can fit in the remaining address space */
 	if (likely(addr > len)) {
 		vma = find_vma(mm, addr-len);
-		if (!vma || addr <= vma->vm_start) {
+		if (!vma || addr <= vm_start_gap(vma)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr-len);
 		}
@@ -199,20 +202,22 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
-		if (likely(!vma || addr+len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr);
 		}
 
 		/* remember the largest hole we saw so far */
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = vma->vm_start-len;
+		addr = vm_start-len;
 		if (do_colour_align)
 			addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-	} while (likely(len < vma->vm_start));
+	} while (likely(len < vm_start));
 
 bottomup:
 	/*
diff --git a/arch/sparc/kernel/sys_sparc_32.c b/arch/sparc/kernel/sys_sparc_32.c
index 42b282fa6112..eeae89bada55 100644
--- a/arch/sparc/kernel/sys_sparc_32.c
+++ b/arch/sparc/kernel/sys_sparc_32.c
@@ -71,7 +71,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 		}
 		if (TASK_SIZE - PAGE_SIZE - len < addr)
 			return -ENOMEM;
-		if (!vmm || addr + len <= vmm->vm_start)
+		if (!vmm || addr + len <= vm_start_gap(vmm))
 			return addr;
 		addr = vmm->vm_end;
 		if (flags & MAP_SHARED)
diff --git a/arch/sparc/kernel/sys_sparc_64.c b/arch/sparc/kernel/sys_sparc_64.c
index 3ee51f189a55..7c98f167f2ff 100644
--- a/arch/sparc/kernel/sys_sparc_64.c
+++ b/arch/sparc/kernel/sys_sparc_64.c
@@ -117,7 +117,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct * vma;
 	unsigned long task_size = TASK_SIZE;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 	int do_color_align;
 
 	if (flags & MAP_FIXED) {
@@ -147,7 +147,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 
 		vma = find_vma(mm, addr);
 		if (task_size - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -181,15 +181,17 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, unsi
 			}
 			return -ENOMEM;
 		}
-		if (likely(!vma || addr + len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		addr = vma->vm_end;
 		if (do_color_align)
@@ -205,7 +207,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long task_size = STACK_TOP32;
-	unsigned long addr = addr0;
+	unsigned long addr = addr0, vm_start;
 	int do_color_align;
 
 	/* This should only ever run for 32-bit processes.  */
@@ -237,7 +239,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 
 		vma = find_vma(mm, addr);
 		if (task_size - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -258,7 +260,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	/* make sure it can fit in the remaining address space */
 	if (likely(addr > len)) {
 		vma = find_vma(mm, addr-len);
-		if (!vma || addr <= vma->vm_start) {
+		if (!vma || addr <= vm_start_gap(vma)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr-len);
 		}
@@ -278,20 +280,22 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
-		if (likely(!vma || addr+len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr);
 		}
 
  		/* remember the largest hole we saw so far */
- 		if (addr + mm->cached_hole_size < vma->vm_start)
- 		        mm->cached_hole_size = vma->vm_start - addr;
+ 		if (addr + mm->cached_hole_size < vm_start)
+ 		        mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = vma->vm_start-len;
+		addr = vm_start - len;
 		if (do_color_align)
 			addr = COLOUR_ALIGN_DOWN(addr, pgoff);
-	} while (likely(len < vma->vm_start));
+	} while (likely(len < vm_start));
 
 bottomup:
 	/*
diff --git a/arch/sparc/mm/hugetlbpage.c b/arch/sparc/mm/hugetlbpage.c
index 07e14535375c..e13e85dbfcd9 100644
--- a/arch/sparc/mm/hugetlbpage.c
+++ b/arch/sparc/mm/hugetlbpage.c
@@ -33,7 +33,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct * vma;
 	unsigned long task_size = TASK_SIZE;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 
 	if (test_thread_flag(TIF_32BIT))
 		task_size = STACK_TOP32;
@@ -67,15 +67,17 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *filp,
 			}
 			return -ENOMEM;
 		}
-		if (likely(!vma || addr + len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 	}
@@ -90,6 +92,7 @@ hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0;
+	unsigned long vm_start;
 
 	/* This should only ever run for 32-bit processes.  */
 	BUG_ON(!test_thread_flag(TIF_32BIT));
@@ -106,7 +109,7 @@ hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	/* make sure it can fit in the remaining address space */
 	if (likely(addr > len)) {
 		vma = find_vma(mm, addr-len);
-		if (!vma || addr <= vma->vm_start) {
+		if (!vma || addr <= vm_start_gap(vma)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr-len);
 		}
@@ -124,18 +127,20 @@ hugetlb_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
-		if (likely(!vma || addr+len <= vma->vm_start)) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (likely(!vma || addr + len <= vm_start)) {
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr);
 		}
 
  		/* remember the largest hole we saw so far */
- 		if (addr + mm->cached_hole_size < vma->vm_start)
- 		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = (vma->vm_start-len) & HPAGE_MASK;
-	} while (likely(len < vma->vm_start));
+		addr = (vm_start - len) & HPAGE_MASK;
+	} while (likely(len < vm_start));
 
 bottomup:
 	/*
@@ -182,7 +187,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 		addr = ALIGN(addr, HPAGE_SIZE);
 		vma = find_vma(mm, addr);
 		if (task_size - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 	if (mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/arch/tile/mm/hugetlbpage.c b/arch/tile/mm/hugetlbpage.c
index 42cfcba4e1ef..184e0339c056 100644
--- a/arch/tile/mm/hugetlbpage.c
+++ b/arch/tile/mm/hugetlbpage.c
@@ -159,7 +159,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 	struct hstate *h = hstate_file(file);
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 
 	if (len > mm->cached_hole_size) {
 		start_addr = mm->free_area_cache;
@@ -185,12 +185,14 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start) {
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-			mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 		addr = ALIGN(vma->vm_end, huge_page_size(h));
 	}
 }
@@ -204,6 +206,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	struct vm_area_struct *vma, *prev_vma;
 	unsigned long base = mm->mmap_base, addr = addr0;
 	unsigned long largest_hole = mm->cached_hole_size;
+	unsigned long vm_start;
 	int first_time = 1;
 
 	/* don't allow allocations above current base */
@@ -234,9 +237,10 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 
 		/*
 		 * new region fits between prev_vma->vm_end and
-		 * vma->vm_start, use it:
+		 * vm_start, use it:
 		 */
-		if (addr + len <= vma->vm_start &&
+		vm_start = vm_start_gap(vma);
+		if (addr + len <= vm_start &&
 			    (!prev_vma || (addr >= prev_vma->vm_end))) {
 			/* remember the address as a hint for next time */
 			mm->cached_hole_size = largest_hole;
@@ -251,13 +255,13 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		}
 
 		/* remember the largest hole we saw so far */
-		if (addr + largest_hole < vma->vm_start)
-			largest_hole = vma->vm_start - addr;
+		if (addr + largest_hole < vm_start)
+			largest_hole = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = (vma->vm_start - len) & huge_page_mask(h);
+		addr = (vm_start - len) & huge_page_mask(h);
 
-	} while (len <= vma->vm_start);
+	} while (len <= vm_start);
 
 fail:
 	/*
@@ -312,7 +316,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 		addr = ALIGN(addr, huge_page_size(h));
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 	if (current->mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index b4d3c3927dd8..6c941b646b82 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -126,7 +126,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 	unsigned long begin, end;
 
 	if (flags & MAP_FIXED)
@@ -141,7 +141,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
 		if (end - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 	if (((flags & MAP_32BIT) || test_thread_flag(TIF_ADDR32))
@@ -172,15 +172,17 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-			mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		addr = vma->vm_end;
 		addr = align_addr(addr, filp, 0);
@@ -196,6 +198,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct vm_area_struct *vma;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0, start_addr;
+	unsigned long vm_start;
 
 	/* requested length too big for entire address space */
 	if (len > TASK_SIZE)
@@ -213,7 +216,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-				(!vma || addr + len <= vma->vm_start))
+				(!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -240,17 +243,19 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		 * return with success:
 		 */
 		vma = find_vma(mm, addr);
-		if (!vma || addr+len <= vma->vm_start)
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start)
 			/* remember the address as a hint for next time */
 			return mm->free_area_cache = addr;
 
 		/* remember the largest hole we saw so far */
-		if (addr + mm->cached_hole_size < vma->vm_start)
-			mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = vma->vm_start-len;
-	} while (len < vma->vm_start);
+		addr = vm_start - len;
+	} while (len < vm_start);
 
 fail:
 	/*
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index f6679a7fb8ca..715459d1849a 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -266,7 +266,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 	struct hstate *h = hstate_file(file);
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	unsigned long start_addr, vm_start;
 
 	if (len > mm->cached_hole_size) {
 	        start_addr = mm->free_area_cache;
@@ -292,12 +292,14 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		if (vma)
+			vm_start = vm_start_gap(vma);
+		if (!vma || addr + len <= vm_start) {
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 		addr = ALIGN(vma->vm_end, huge_page_size(h));
 	}
 }
@@ -313,6 +315,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	unsigned long addr = addr0;
 	unsigned long largest_hole = mm->cached_hole_size;
 	unsigned long start_addr;
+	unsigned long vm_start;
 
 	/* don't allow allocations above current base */
 	if (mm->free_area_cache > base)
@@ -340,7 +343,8 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		if (!vma)
 			return addr;
 
-		if (addr + len <= vma->vm_start) {
+		vm_start = vm_start_gap(vma);
+		if (addr + len <= vm_start) {
 			/* remember the address as a hint for next time */
 		        mm->cached_hole_size = largest_hole;
 		        return (mm->free_area_cache = addr);
@@ -351,12 +355,12 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		}
 
 		/* remember the largest hole we saw so far */
-		if (addr + largest_hole < vma->vm_start)
-		        largest_hole = vma->vm_start - addr;
+		if (addr + largest_hole < vm_start)
+			largest_hole = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = (vma->vm_start - len) & huge_page_mask(h);
-	} while (len <= vma->vm_start);
+		addr = (vm_start - len) & huge_page_mask(h);
+	} while (len <= vm_start);
 
 fail:
 	/*
@@ -411,7 +415,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 		addr = ALIGN(addr, huge_page_size(h));
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 	if (mm->get_unmapped_area == arch_get_unmapped_area)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 001ef01d2fe2..b82ac06a5859 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -169,7 +169,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 		addr = ALIGN(addr, huge_page_size(h));
 		vma = find_vma(mm, addr);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)))
 			return addr;
 	}
 
@@ -198,7 +198,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 			return -ENOMEM;
 		}
 
-		if (!vma || addr + len <= vma->vm_start) {
+		if (!vma || addr + len <= vm_start_gap(vma)) {
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 4ff475066ca9..ce58c9866908 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -283,11 +283,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 
 	/* We don't show the stack guard page in /proc/maps */
 	start = vma->vm_start;
-	if (stack_guard_page_start(vma, start))
-		start += PAGE_SIZE;
 	end = vma->vm_end;
-	if (stack_guard_page_end(vma, end))
-		end -= PAGE_SIZE;
 
 	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
 			start,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5df691eb555f..94ebf38b0447 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1032,34 +1032,6 @@ int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
 
-/* Is the vma a continuation of the stack vma above it? */
-static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)
-{
-	return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
-}
-
-static inline int stack_guard_page_start(struct vm_area_struct *vma,
-					     unsigned long addr)
-{
-	return (vma->vm_flags & VM_GROWSDOWN) &&
-		(vma->vm_start == addr) &&
-		!vma_growsdown(vma->vm_prev, addr);
-}
-
-/* Is the vma a continuation of the stack vma below it? */
-static inline int vma_growsup(struct vm_area_struct *vma, unsigned long addr)
-{
-	return vma && (vma->vm_start == addr) && (vma->vm_flags & VM_GROWSUP);
-}
-
-static inline int stack_guard_page_end(struct vm_area_struct *vma,
-					   unsigned long addr)
-{
-	return (vma->vm_flags & VM_GROWSUP) &&
-		(vma->vm_end == addr) &&
-		!vma_growsup(vma->vm_next, addr);
-}
-
 extern pid_t
 vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group);
 
@@ -1469,6 +1441,7 @@ unsigned long ra_submit(struct file_ra_state *ra,
 			struct address_space *mapping,
 			struct file *filp);
 
+extern unsigned long stack_guard_gap;
 /* Generic expand stack which grows the stack according to GROWS{UP,DOWN} */
 extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
 
@@ -1497,6 +1470,30 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
 	return vma;
 }
 
+static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
+{
+	unsigned long vm_start = vma->vm_start;
+
+	if (vma->vm_flags & VM_GROWSDOWN) {
+		vm_start -= stack_guard_gap;
+		if (vm_start > vma->vm_start)
+			vm_start = 0;
+	}
+	return vm_start;
+}
+
+static inline unsigned long vm_end_gap(struct vm_area_struct *vma)
+{
+	unsigned long vm_end = vma->vm_end;
+
+	if (vma->vm_flags & VM_GROWSUP) {
+		vm_end += stack_guard_gap;
+		if (vm_end < vma->vm_end)
+			vm_end = -PAGE_SIZE;
+	}
+	return vm_end;
+}
+
 static inline unsigned long vma_pages(struct vm_area_struct *vma)
 {
 	return (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
diff --git a/mm/memory.c b/mm/memory.c
index 93347cbecf07..863110ffa1e7 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1623,12 +1623,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 	return page;
 }
 
-static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
-{
-	return stack_guard_page_start(vma, addr) ||
-	       stack_guard_page_end(vma, addr+PAGE_SIZE);
-}
-
 /**
  * __get_user_pages() - pin user pages in memory
  * @tsk:	task_struct of target task
@@ -1792,11 +1786,6 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				int ret;
 				unsigned int fault_flags = 0;
 
-				/* For mlock, just skip the stack guard page. */
-				if (foll_flags & FOLL_MLOCK) {
-					if (stack_guard_page(vma, start))
-						goto next_page;
-				}
 				if (foll_flags & FOLL_WRITE)
 					fault_flags |= FAULT_FLAG_WRITE;
 				if (nonblocking)
@@ -3103,40 +3092,6 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	return ret;
 }
 
-/*
- * This is like a special single-page "expand_{down|up}wards()",
- * except we must first make sure that 'address{-|+}PAGE_SIZE'
- * doesn't hit another vma.
- */
-static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
-{
-	address &= PAGE_MASK;
-	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
-		struct vm_area_struct *prev = vma->vm_prev;
-
-		/*
-		 * Is there a mapping abutting this one below?
-		 *
-		 * That's only ok if it's the same stack mapping
-		 * that has gotten split..
-		 */
-		if (prev && prev->vm_end == address)
-			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
-
-		expand_downwards(vma, address - PAGE_SIZE);
-	}
-	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
-		struct vm_area_struct *next = vma->vm_next;
-
-		/* As VM_GROWSDOWN but s/below/above/ */
-		if (next && next->vm_start == address + PAGE_SIZE)
-			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
-
-		expand_upwards(vma, address + PAGE_SIZE);
-	}
-	return 0;
-}
-
 /*
  * We enter with non-exclusive mmap_sem (to exclude vma changes,
  * but allow concurrent faults), and pte mapped but not yet locked.
@@ -3152,10 +3107,6 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	pte_unmap(page_table);
 
-	/* Check if we need to add a guard page to the stack */
-	if (check_stack_guard_page(vma, address) < 0)
-		return VM_FAULT_SIGBUS;
-
 	/* Use the zero-page for reads */
 	if (!(flags & FAULT_FLAG_WRITE)) {
 		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
diff --git a/mm/mmap.c b/mm/mmap.c
index 16231bc57335..d295e7f5fcbb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -259,6 +259,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	unsigned long rlim, retval;
 	unsigned long newbrk, oldbrk;
 	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *next;
 	unsigned long min_brk;
 
 	down_write(&mm->mmap_sem);
@@ -303,7 +304,8 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 	}
 
 	/* Check against existing mmap mappings. */
-	if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
+	next = find_vma(mm, oldbrk);
+	if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
 		goto out;
 
 	/* Ok, looks good - let it rip. */
@@ -1429,8 +1431,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma;
-	unsigned long start_addr;
+	struct vm_area_struct *vma, *prev;
+	unsigned long start_addr, vm_start, prev_end;
 
 	if (len > TASK_SIZE)
 		return -ENOMEM;
@@ -1440,9 +1442,10 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
-		vma = find_vma(mm, addr);
+		vma = find_vma_prev(mm, addr, &prev);
 		if (TASK_SIZE - len >= addr &&
-		    (!vma || addr + len <= vma->vm_start))
+		    (!vma || addr + len <= vm_start_gap(vma)) &&
+		    (!prev || addr >= vm_end_gap(prev)))
 			return addr;
 	}
 	if (len > mm->cached_hole_size) {
@@ -1453,7 +1456,17 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	}
 
 full_search:
-	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+	for (vma = find_vma_prev(mm, addr, &prev); ; prev = vma,
+						vma = vma->vm_next) {
+		if (prev) {
+			prev_end = vm_end_gap(prev);
+			if (addr < prev_end) {
+				addr = prev_end;
+				/* If vma already violates gap, forget it */
+				if (vma && addr > vma->vm_start)
+					addr = vma->vm_start;
+			}
+		}
 		/* At this point:  (!vma || addr < vma->vm_end). */
 		if (TASK_SIZE - len < addr) {
 			/*
@@ -1468,16 +1481,16 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 			}
 			return -ENOMEM;
 		}
-		if (!vma || addr + len <= vma->vm_start) {
+		vm_start = vma ? vm_start_gap(vma) : TASK_SIZE;
+		if (addr + len <= vm_start) {
 			/*
 			 * Remember the place where we stopped the search:
 			 */
 			mm->free_area_cache = addr + len;
 			return addr;
 		}
-		if (addr + mm->cached_hole_size < vma->vm_start)
-		        mm->cached_hole_size = vma->vm_start - addr;
-		addr = vma->vm_end;
+		if (addr + mm->cached_hole_size < vm_start)
+			mm->cached_hole_size = vm_start - addr;
 	}
 }
 #endif	
@@ -1501,9 +1514,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 			  const unsigned long len, const unsigned long pgoff,
 			  const unsigned long flags)
 {
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma, *prev;
 	struct mm_struct *mm = current->mm;
 	unsigned long addr = addr0, start_addr;
+	unsigned long vm_start, prev_end;
 
 	/* requested length too big for entire address space */
 	if (len > TASK_SIZE)
@@ -1515,9 +1529,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	/* requesting a specific address */
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
-		vma = find_vma(mm, addr);
+		vma = find_vma_prev(mm, addr, &prev);
 		if (TASK_SIZE - len >= addr &&
-				(!vma || addr + len <= vma->vm_start))
+				(!vma || addr + len <= vm_start_gap(vma)) &&
+				(!prev || addr >= vm_end_gap(prev)))
 			return addr;
 	}
 
@@ -1541,18 +1556,21 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		 * else if new region fits below vma->vm_start,
 		 * return with success:
 		 */
-		vma = find_vma(mm, addr);
-		if (!vma || addr+len <= vma->vm_start)
+		vma = find_vma_prev(mm, addr, &prev);
+		vm_start = vma ? vm_start_gap(vma) : mm->mmap_base;
+		prev_end = prev ? vm_end_gap(prev) : low_limit;
+
+		if (addr + len <= vm_start && addr >= prev_end)
 			/* remember the address as a hint for next time */
 			return (mm->free_area_cache = addr);
 
  		/* remember the largest hole we saw so far */
- 		if (addr + mm->cached_hole_size < vma->vm_start)
- 		        mm->cached_hole_size = vma->vm_start - addr;
+ 		if (addr + mm->cached_hole_size < vm_start)
+ 		        mm->cached_hole_size = vm_start - addr;
 
 		/* try just below the current vma->vm_start */
-		addr = vma->vm_start-len;
-	} while (len < vma->vm_start);
+		addr = vm_start-len;
+	} while (len < vm_start);
 
 fail:
 	/*
@@ -1699,7 +1717,8 @@ find_vma_prev(struct mm_struct *mm, unsigned long addr,
  * update accounting. This is shared with both the
  * grow-up and grow-down cases.
  */
-static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
+static int acct_stack_growth(struct vm_area_struct *vma,
+			     unsigned long size, unsigned long grow)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	struct rlimit *rlim = current->signal->rlim;
@@ -1752,32 +1771,40 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
  */
 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 {
-	int error;
+	struct vm_area_struct *next;
+	unsigned long gap_addr;
+	int error = 0;
 
 	if (!(vma->vm_flags & VM_GROWSUP))
 		return -EFAULT;
 
-	/*
-	 * We must make sure the anon_vma is allocated
-	 * so that the anon_vma locking is not a noop.
-	 */
+	/* Guard against wrapping around to address 0. */
+	address &= PAGE_MASK;
+	address += PAGE_SIZE;
+	if (!address)
+		return -ENOMEM;
+
+	/* Enforce stack_guard_gap */
+	gap_addr = address + stack_guard_gap;
+	if (gap_addr < address)
+		return -ENOMEM;
+	next = vma->vm_next;
+	if (next && next->vm_start < gap_addr) {
+		if (!(next->vm_flags & VM_GROWSUP))
+			return -ENOMEM;
+		/* Check that both stack segments have the same anon_vma? */
+	}
+
+	/* We must make sure the anon_vma is allocated. */
 	if (unlikely(anon_vma_prepare(vma)))
 		return -ENOMEM;
-	vma_lock_anon_vma(vma);
 
 	/*
 	 * vma->vm_start/vm_end cannot change under us because the caller
 	 * is required to hold the mmap_sem in read mode.  We need the
 	 * anon_vma lock to serialize against concurrent expand_stacks.
-	 * Also guard against wrapping around to address 0.
 	 */
-	if (address < PAGE_ALIGN(address+4))
-		address = PAGE_ALIGN(address+4);
-	else {
-		vma_unlock_anon_vma(vma);
-		return -ENOMEM;
-	}
-	error = 0;
+	vma_lock_anon_vma(vma);
 
 	/* Somebody else might have raced and expanded it already */
 	if (address > vma->vm_end) {
@@ -1807,27 +1834,36 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 int expand_downwards(struct vm_area_struct *vma,
 				   unsigned long address)
 {
+	struct vm_area_struct *prev;
+	unsigned long gap_addr;
 	int error;
 
-	/*
-	 * We must make sure the anon_vma is allocated
-	 * so that the anon_vma locking is not a noop.
-	 */
-	if (unlikely(anon_vma_prepare(vma)))
-		return -ENOMEM;
-
 	address &= PAGE_MASK;
 	error = security_file_mmap(NULL, 0, 0, 0, address, 1);
 	if (error)
 		return error;
 
-	vma_lock_anon_vma(vma);
+	/* Enforce stack_guard_gap */
+	gap_addr = address - stack_guard_gap;
+	if (gap_addr > address)
+		return -ENOMEM;
+	prev = vma->vm_prev;
+	if (prev && prev->vm_end > gap_addr) {
+		if (!(prev->vm_flags & VM_GROWSDOWN))
+			return -ENOMEM;
+		/* Check that both stack segments have the same anon_vma? */
+	}
+
+	/* We must make sure the anon_vma is allocated. */
+	if (unlikely(anon_vma_prepare(vma)))
+		return -ENOMEM;
 
 	/*
 	 * vma->vm_start/vm_end cannot change under us because the caller
 	 * is required to hold the mmap_sem in read mode.  We need the
 	 * anon_vma lock to serialize against concurrent expand_stacks.
 	 */
+	vma_lock_anon_vma(vma);
 
 	/* Somebody else might have raced and expanded it already */
 	if (address < vma->vm_start) {
@@ -1851,6 +1887,22 @@ int expand_downwards(struct vm_area_struct *vma,
 	return error;
 }
 
+/* enforced gap between the expanding stack and other mappings. */
+unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
+
+static int __init cmdline_parse_stack_guard_gap(char *p)
+{
+	unsigned long val;
+	char *endptr;
+
+	val = simple_strtoul(p, &endptr, 10);
+	if (!*endptr)
+		stack_guard_gap = val << PAGE_SHIFT;
+
+	return 0;
+}
+__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
+
 #ifdef CONFIG_STACK_GROWSUP
 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 {