linux-kernel - Re: [PATCH 6/8] HWPOISON, hugetlb: soft offlining for hugepage

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Message-ID: <20100825030202.GB15129@localhost>
Date:	Wed, 25 Aug 2010 11:02:02 +0800
From:	Wu Fengguang <fengguang.wu@...el.com>
To:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	Jun'ichi Nomura <j-nomura@...jp.nec.com>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/8] HWPOISON, hugetlb: soft offlining for hugepage

> +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
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