Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753841AbcDTF4F (ORCPT <rfc822;w@1wt.eu>);
	Wed, 20 Apr 2016 01:56:05 -0400
Received: from mail.linuxfoundation.org ([140.211.169.12]:37821 "EHLO
	mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751279AbcDTF4D (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 20 Apr 2016 01:56:03 -0400
Date: Wed, 20 Apr 2016 14:55:58 +0900
From: Greg KH <gregkh@linuxfoundation.org>
To: Nikhilesh Reddy <reddyn@codeaurora.org>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Umount failing due to a file leak on 3.18 Android
Message-ID: <20160420055558.GB6031@kroah.com>
References: <5716DAC3.4070404@codeaurora.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5716DAC3.4070404@codeaurora.org>
User-Agent: Mutt/1.6.0 (2016-04-01)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1287
Lines: 31

On Tue, Apr 19, 2016 at 06:26:27PM -0700, Nikhilesh Reddy wrote:
> Hi
> 
> I am looking into a bug that results in umount failures ( since there is a mount ref from the leaked file that is never freed on the mount )
> 
> The issue seems to be a result of the following callstack
> 
>     39.958104:   <6> Call trace:
>     39.958108:   <2> [<ffffffc0001baa58>] fput+0x1e0/0x1f8
>     39.958113:   <2> [<ffffffc0001b6ce8>] filp_close+0xa0/0xb8
>     39.958119:   <2> [<ffffffc0001d3ca8>] put_files_struct+0x88/0xf0
>     39.958123:   <2> [<ffffffc000973c40>] binder_deferred_func+0x6a8/0x704
>     39.958129:   <2> [<ffffffc0000ba32c>] process_one_work+0x238/0x3f0
>     39.958133:   <2> [<ffffffc0000bb160>] worker_thread+0x2f8/0x418
> 
> What seems to occur is that once in a while a file ( say a.txt) is fput in the above stack 
> right as the task is being killed
> 
> And then we see that the  fput schedules a delayed_fput_work on this file
> 
> But when the function delayed_fput() is actually run :
> 	the file that was put i.e this a.txt is not in the delayed_fput_list
> 
> Any chance you can help me get to the bottom of this leak?
> I dont understand why the delayed_fput_list is missing the file.

3.18 is very old, can you duplicate this on 4.5 or newer?

thanks,

greg k-h