Merge branch 'develop' of 10.10.10.29:/home/rockchip/kernel into develop

[firefly-linux-kernel-4.4.55.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index babb991fb02ba69bdfec04347a14dc2e81d9a836..53c1da0d04a68d02bd1fd9eba8c925ceda59fec8 100644 (file)
--- 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;
 }