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Date: Wed, 25 Aug 2010 11:02:02 +0800
From: Wu Fengguang <fengguang.wu@intel.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux-foundation.org>,
        Mel Gorman <mel@csn.ul.ie>, "Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>,
        linux-mm <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/8] HWPOISON, hugetlb: soft offlining for hugepage
Message-ID: <20100825030202.GB15129@localhost>
References: <1282694127-14609-1-git-send-email-n-horiguchi@ah.jp.nec.com>
 <1282694127-14609-7-git-send-email-n-horiguchi@ah.jp.nec.com>
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> +static int is_hugepage_on_freelist(struct page *hpage)
> +{
> +	struct page *page;
> +	struct page *tmp;
> +	struct hstate *h = page_hstate(hpage);
> +	int nid = page_to_nid(hpage);
> +
> +	spin_lock(&hugetlb_lock);
> +	list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru) {
> +		if (page == hpage) {
> +			spin_unlock(&hugetlb_lock);
> +			return 1;
> +		}
> +	}
> +	spin_unlock(&hugetlb_lock);
> +	return 0;
> +}

Ha! That looks better than the page_count test in my previous email.

> +void isolate_hwpoisoned_huge_page(struct page *hpage)
> +{
> +	lock_page(hpage);
> +	if (is_hugepage_on_freelist(hpage))
> +		__isolate_hwpoisoned_huge_page(hpage);
> +	unlock_page(hpage);
> +}

However it should still be racy if the test/isolate actions are
not performed in the same hugetlb_lock.

Thanks,
Fengguang