From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 26 Feb 2008 10:48:34 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 14/15] memcg: simplify force_empty and move_lists
Message-Id: <20080226104834.5bbd7f20.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <Pine.LNX.4.64.0802252349100.27067@blonde.site>
References: <Pine.LNX.4.64.0802252327490.27067@blonde.site>
	<Pine.LNX.4.64.0802252349100.27067@blonde.site>
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To: Hugh Dickins <hugh@veritas.com>, Hirokazu Takahashi <taka@valinux.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, YAMAMOTO Takashi <yamamoto@valinux.co.jp>, linux-mm@kvack.org
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Claim again ;)
On Mon, 25 Feb 2008 23:50:27 +0000 (GMT)
Hugh Dickins <hugh@veritas.com>, Hirokazu Takahashi <taka@valinux.co.jp> wrote:

> +		get_page(page);
How about this?
> +		spin_unlock_irqrestore(&mz->lru_lock, flags);
		local_irq_save(flags):
		if (TestSetPageLocked(page)) {
	> +		mem_cgroup_uncharge_page(page);
	> +		put_page(page);
	> +		if (--count <= 0) {
	> +			count = FORCE_UNCHARGE_BATCH;
	> +			cond_resched();
	>  		}
	> +		spin_lock_irqsave(&mz->lru_lock, flags);
			unlock_page(page);
		}
		local_irq_restore(flags);

page's lock bit guarantees 100% safe against page migration.
(And most of other charging/uncharging callers.)

Thanks,
-Kame

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