linux-kernel - Re: [PATCH 0/3] ramzswap: Eliminate stale data from compressed memory (v2 resend)

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Message-ID: <4BF1022F.2030307@vflare.org>
Date:	Mon, 17 May 2010 14:15:35 +0530
From:	Nitin Gupta <ngupta@...are.org>
To:	Pekka Enberg <penberg@...helsinki.fi>
CC:	Greg KH <greg@...ah.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Nigel Cunningham <nigel@...onice.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>,
	Cyp <cyp561@...il.com>, driverdev <devel@...verdev.osuosl.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, hughd@...gle.com
Subject: Re: [PATCH 0/3] ramzswap: Eliminate stale data from compressed memory
 	(v2 resend)

On 05/17/2010 11:40 AM, Pekka Enberg wrote:
> On Mon, May 17, 2010 at 8:32 AM, Nitin Gupta <ngupta@...are.org> wrote:
>> Resending as Greg wanted.
>>
>> (tested on mainline but should apply to linux-next cleanly)
>>
>>
>>  * Changelog: v2 vs initial patches
>>   - directly add swap free callback to block_device_operations
>>     instead of using 'notifiers' for various swap events.
>>
>> ramzswap driver creates RAM based block devices which can be
>> used (only) as swap disks. Pages swapped to these disks are
>> compressed and stored in memory itself.
>>
>> However, these devices do not get any notification when a swap
>> slot is freed (swap_map[i] reaches 0). So, we cannot free memory
>> allocated corresponding to this swap slot. Such stale data can
>> quickly accumulate in (compressed) memory defeating the whole
>> purpose of such devices.
>>
>> To overcome this problem, we now add a callback in struct
>> block_device_operations which is called as soon as a swap
>> slot is freed.
>>
>> Nitin Gupta (3):
>>  Add flag to identify block swap devices
>>  Add swap slot free callback to block_device_operations
>>  ramzswap: Handler for swap slot free callback
>>
>>  drivers/staging/ramzswap/TODO           |    5 -----
>>  drivers/staging/ramzswap/ramzswap_drv.c |   22 +++++++++++++---------
>>  include/linux/blkdev.h                  |    2 ++
>>  include/linux/swap.h                    |    1 +
>>  mm/swapfile.c                           |    5 +++++
>>  5 files changed, 21 insertions(+), 14 deletions(-)
>>  delete mode 100644 drivers/staging/ramzswap/TODO
> 
> Nitin, please retain ACKs when resending patches.
> 
> Acked-by: Pekka Enberg <penberg@...helsinki.fi>
> 
> for the whole series.

Sorry, I forgot to include Ack lines. Here are the remaining Acks:

Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Acked-by: Nigel Cunningham <nigel@...onice.net>

Thanks you all for reviews.
Nitin
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