return ret;
}
+/*
+ * This is like a special single-page "expand_downwards()",
+ * 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;
+
+ expand_stack(vma, address);
+ }
+ return 0;
+}
+
/*
* We enter with non-exclusive mmap_sem (to exclude vma changes,
* but allow concurrent faults), and pte mapped but not yet locked.
spinlock_t *ptl;
pte_t entry;
+ 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);