mm: migration: avoid race between shift_arg_pages() and rmap_walk() during migration...
[linux-2.6.git] / fs / exec.c
index e6e94c6..9badbc0 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -242,9 +242,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
         * use STACK_TOP because that can depend on attributes which aren't
         * configured yet.
         */
+       BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
        vma->vm_end = STACK_TOP_MAX;
        vma->vm_start = vma->vm_end - PAGE_SIZE;
-       vma->vm_flags = VM_STACK_FLAGS;
+       vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        INIT_LIST_HEAD(&vma->anon_vma_chain);
        err = insert_vm_struct(mm, vma);
@@ -616,6 +617,7 @@ int setup_arg_pages(struct linux_binprm *bprm,
        else if (executable_stack == EXSTACK_DISABLE_X)
                vm_flags &= ~VM_EXEC;
        vm_flags |= mm->def_flags;
+       vm_flags |= VM_STACK_INCOMPLETE_SETUP;
 
        ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
                        vm_flags);
@@ -630,6 +632,9 @@ int setup_arg_pages(struct linux_binprm *bprm,
                        goto out_unlock;
        }
 
+       /* mprotect_fixup is overkill to remove the temporary stack flags */
+       vma->vm_flags &= ~VM_STACK_INCOMPLETE_SETUP;
+
        stack_expand = 131072UL; /* randomly 32*4k (or 2*64k) pages */
        stack_size = vma->vm_end - vma->vm_start;
        /*