From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH] shmem: init on stack vmas
Date: Mon, 13 Jan 2014 12:32:21 -0800
Message-ID: <52D44D55.2090709@intel.com>
References: <1389638777-31891-1-git-send-email-jbacik@fb.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
To: Josef Bacik <jbacik@fb.com>, linux-mm@kvack.org,
	linux-fsdevel@vger.kernel.org
Return-path: <linux-fsdevel-owner@vger.kernel.org>
Received: from mga02.intel.com ([134.134.136.20]:28863 "EHLO mga02.intel.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751395AbaAMUdu (ORCPT <rfc822;linux-fsdevel@vger.kernel.org>);
	Mon, 13 Jan 2014 15:33:50 -0500
In-Reply-To: <1389638777-31891-1-git-send-email-jbacik@fb.com>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On 01/13/2014 10:46 AM, Josef Bacik wrote:
> We were hitting a weird bug with our cgroup stuff because shmem uses on stack
> vmas.  These aren't properly init'ed so we'd have garbage in vma->mm and bad
> things would happen.  Fix this by just init'ing to empty structs.  Thanks,
...
>  static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
>  			struct shmem_inode_info *info, pgoff_t index)
>  {
> -	struct vm_area_struct pvma;
> +	struct vm_area_struct pvma = {};

What does that code do if it needs an mm and doesn't find one?