linux-kernel - Re: [patch 11/17] hugetlbfs: support larger than MAX

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Message-ID: <20080411081317.GQ10019@one.firstfloor.org>
Date:	Fri, 11 Apr 2008 10:13:17 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	npiggin@...e.de
Cc:	akpm@...ux-foundation.org, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org, pj@....com,
	andi@...stfloor.org, kniht@...ux.vnet.ibm.com
Subject: Re: [patch 11/17] hugetlbfs: support larger than MAX_ORDER

>  	spin_lock(&hugetlb_lock);
> -	if (h->surplus_huge_pages_node[nid]) {
> +	if (h->surplus_huge_pages_node[nid] && h->order <= MAX_ORDER) {

As Andrew Hastings pointed out earlier this all needs to be h->order < MAX_ORDER
[got pretty much all the checks wrong off by one]. It won't affect anything
on x86-64 but might cause problems on archs which have exactly MAX_ORDER
sized huge pages.

>  		update_and_free_page(h, page);
>  		h->surplus_huge_pages--;
>  		h->surplus_huge_pages_node[nid]--;
> @@ -220,6 +221,9 @@ static struct page *alloc_fresh_huge_pag
>  {
>  	struct page *page;
>  
> +	if (h->order > MAX_ORDER)

>= etc.

-Andi
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