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Message-ID: <4BE3C4CC.8050307@cs.helsinki.fi>
Date: Fri, 07 May 2010 10:44:12 +0300
From: Pekka Enberg <penberg@cs.helsinki.fi>
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To: Nitin Gupta <ngupta@vflare.org>
CC: Greg KH <greg@kroah.com>, Linus Torvalds <torvalds@linux-foundation.org>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>, Cyp <cyp561@gmail.com>,
       Minchan Kim <minchan.kim@gmail.com>, Al Viro <viro@ZenIV.linux.org.uk>,
       Christoph Hellwig <hch@infradead.org>,
       Jens Axboe <jens.axboe@oracle.com>, Andi Kleen <andi@firstfloor.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       driverdev <devel@driverdev.osuosl.org>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/3] ramzswap: Eliminate stale data from compressed memory
 (v2)
References: <1273217107-2023-1-git-send-email-ngupta@vflare.org>
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Nitin Gupta kirjoitti:
> (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

The series looks good to me:

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>