From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932631AbbBBFJQ (ORCPT <rfc822;w@1wt.eu>);
	Mon, 2 Feb 2015 00:09:16 -0500
Received: from mail-pa0-f41.google.com ([209.85.220.41]:62367 "EHLO
	mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751240AbbBBFJP (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 2 Feb 2015 00:09:15 -0500
Date: Mon, 2 Feb 2015 14:09:12 +0900
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>, Nitin Gupta <ngupta@vflare.org>,
        Jerome Marchand <jmarchan@redhat.com>,
        Ganesh Mahendran <opensource.ganesh@gmail.com>
Subject: Re: [PATCH v1 2/2] zram: remove init_lock in zram_make_request
Message-ID: <20150202050912.GA443@swordfish>
References: <20150129060604.GC2555@swordfish>
 <20150129063505.GA32331@blaptop>
 <20150129070835.GD2555@swordfish>
 <20150130144145.GA2840@blaptop>
 <20150201145036.GA1290@swordfish>
 <20150202013028.GB6402@blaptop>
 <20150202014800.GA6977@swordfish>
 <20150202024405.GD6402@blaptop>
 <20150202040124.GE6977@swordfish>
 <20150202042847.GG6402@blaptop>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20150202042847.GG6402@blaptop>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


the patch mosly looks good, except for one place:

On (02/02/15 13:28), Minchan Kim wrote:
> @@ -783,6 +812,8 @@ static ssize_t disksize_store(struct device *dev,
>  		goto out_destroy_comp;
>  	}
>  
> +	init_waitqueue_head(&zram->io_done);
> +	zram_meta_get(zram);

it was
+       init_completion(&zram->io_done);
+       atomic_set(&zram->refcount, 1);

I think we need to replace zram_meta_get(zram) with atomic_set(&zram->refcount, 1).

->refcount is 0 by default and atomic_inc_not_zero(&zram->refcount) will not
increment it here, nor anywhere else.


>  	zram->meta = meta;
>  	zram->comp = comp;
>  	zram->disksize = disksize;
> @@ -838,8 +869,8 @@ static ssize_t reset_store(struct device *dev,
>  	/* Make sure all pending I/O is finished */
>  	fsync_bdev(bdev);
>  	bdput(bdev);
> -

[..]

> @@ -1041,6 +1075,7 @@ static int create_device(struct zram *zram, int device_id)
>  	int ret = -ENOMEM;
>  
>  	init_rwsem(&zram->init_lock);
> +	atomic_set(&zram->refcount, 0);

sorry, I forgot that zram is kzalloc()-ated. so we can drop

	atomic_set(&zram->refcount, 0)

>  	zram->queue = blk_alloc_queue(GFP_KERNEL);
>  	if (!zram->queue) {


	-ss