X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=mm%2Fmemory.c;h=53c1da0d04a68d02bd1fd9eba8c925ceda59fec8;hb=3332f84e0b969bd699d783e00e72a9110929eeed;hp=babb991fb02ba69bdfec04347a14dc2e81d9a836;hpb=058daedc8311ab42702dfe29d3ff16dff7e7eaf8;p=firefly-linux-kernel-4.4.55.git

diff --git a/mm/memory.c b/mm/memory.c
index babb991fb02b..53c1da0d04a6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2630,21 +2630,35 @@ out_release:
 }
 
 /*
- * This is like a special single-page "expand_downwards()",
- * except we must first make sure that 'address-PAGE_SIZE'
+ * 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.
- *
- * The "find_vma()" will do the right thing even if we wrap
  */
 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) {
-		address -= PAGE_SIZE;
-		if (find_vma(vma->vm_mm, address) != vma)
-			return -ENOMEM;
+		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_stack(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_stack(vma, address);
+		expand_upwards(vma, address + PAGE_SIZE);
 	}
 	return 0;
 }