fix checks for expand-in-place mremap

Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/mm/mremap.c b/mm/mremap.c
index 90e422c9f410462652ca06d56b19f404752dd515..9d0753983dcba6db53bbf540ecc8f50e24bdb9a8 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -27,6 +27,10 @@
 
 #include "internal.h"
 
+#ifndef arch_mmap_check
+#define arch_mmap_check(addr, len, flags)      (0)
+#endif
+
 static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
 {
        pgd_t *pgd;
@@ -368,12 +372,17 @@ out:
 
 static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
 {
+       unsigned long end = vma->vm_end + delta;
        unsigned long max_addr = TASK_SIZE;
        if (vma->vm_next)
                max_addr = vma->vm_next->vm_start;
-       if (max_addr - vma->vm_end < delta)
+       if (max_addr < end || end < vma->vm_end)
+               return 0;
+       if (arch_mmap_check(vma->vm_start, end - vma->vm_start, MAP_FIXED))
+               return 0;
+       if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
+                             0, MAP_FIXED) & ~PAGE_MASK)
                return 0;
-       /* we need to do arch-specific checks here */
        return 1;
 }