Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index 9b3b73f..6b2ab10 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2760,21 +2760,35 @@ 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;
 }
@@ -2792,24 +2806,23 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
        spinlock_t *ptl;
        pte_t entry;
 
-       if (check_stack_guard_page(vma, address) < 0) {
-               pte_unmap(page_table);
+       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),
                                                vma->vm_page_prot));
-               ptl = pte_lockptr(mm, pmd);
-               spin_lock(ptl);
+               page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
                if (!pte_none(*page_table))
                        goto unlock;
                goto setpte;
        }
 
        /* Allocate our own private page. */
-       pte_unmap(page_table);
-
        if (unlikely(anon_vma_prepare(vma)))
                goto oom;
        page = alloc_zeroed_user_highpage_movable(vma, address);