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From: Christoph Lameter <clameter@engr.sgi.com>
To: Andy Whitcroft <apw@shadowen.org>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH 1/5] Lumpy Reclaim V3
Date: Wed, 28 Feb 2007 10:14:30 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0702281008330.21257@schroedinger.engr.sgi.com> (raw)
In-Reply-To: <96f80944962593738d72a803797dbddc@kernel>

On Tue, 27 Feb 2007, Andy Whitcroft wrote:

> +static int __isolate_lru_page(struct page *page, int active)
> +{
> +	int ret = -EINVAL;
> +
> +	if (PageLRU(page) && (PageActive(page) == active)) {
> +		ret = -EBUSY;
> +		if (likely(get_page_unless_zero(page))) {
> +			/*
> +			 * Be careful not to clear PageLRU until after we're
> +			 * sure the page is not being freed elsewhere -- the
> +			 * page release code relies on it.
> +			 */
> +			ClearPageLRU(page);
> +			ret = 0;

Is that really necessary? PageLRU is clear when a page is freed right? 
And clearing PageLRU requires the zone->lru_lock since we have to move it 
off the LRU.

> -			ClearPageLRU(page);
> -			target = dst;
> +		active = PageActive(page);

Why are we saving the active state? Page cannot be moved between LRUs 
while we hold the lru lock anyways.

  reply	other threads:[~2007-02-28 18:14 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-27 19:33 [PATCH 0/5] Lumpy Reclaim V4 Andy Whitcroft
2007-02-27 19:34 ` [PATCH 1/5] Lumpy Reclaim V3 Andy Whitcroft
2007-02-28 18:14   ` Christoph Lameter [this message]
2007-03-02 15:45     ` Andy Whitcroft
2007-02-27 19:34 ` [PATCH 2/5] lumpy: isolate_lru_pages wants to specifically take active or inactive pages Andy Whitcroft
2007-02-28 18:17   ` Christoph Lameter
2007-03-02 15:57     ` Andy Whitcroft
2007-02-27 19:35 ` [PATCH 3/5] lumpy: ensure that we compare PageActive and active safely Andy Whitcroft
2007-02-27 19:35 ` [PATCH 4/5] lumpy: update commentry on subtle comparisons and rounding assumptions Andy Whitcroft
2007-02-27 19:36 ` [PATCH 5/5] lumpy: only check for valid pages when holes are present Andy Whitcroft

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