linux-kernel - Re: [PATCH] hugetlb: call arch_prepare

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Message-Id: <200808060136.17277.nickpiggin@yahoo.com.au>
Date:	Wed, 6 Aug 2008 01:36:16 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Gerald Schaefer <gerald.schaefer@...ibm.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-s390@...r.kernel.org, schwidefsky@...ibm.com,
	heiko.carstens@...ibm.com, Nishanth Aravamudan <nacc@...ibm.com>,
	Adam Litke <agl@...ibm.com>
Subject: Re: [PATCH] hugetlb: call arch_prepare_hugepage() for surplus pages

On Wednesday 06 August 2008 01:29, Gerald Schaefer wrote:
> From: Gerald Schaefer <gerald.schaefer@...ibm.com>
>
> The s390 software large page emulation implements shared page tables
> by using page->index of the first tail page from a compound large page
> to store page table information. This is set up in arch_prepare_hugepage(),
> which is called from alloc_fresh_huge_page_node().
>
> A similar call to arch_prepare_hugepage() is missing for surplus large
> pages that are allocated in alloc_buddy_huge_page(), which breaks the
> software emulation mode for (surplus) large pages on s390. This patch
> adds the missing call to arch_prepare_hugepage(). It will have no effect
> on other architectures where arch_prepare_hugepage() is a nop.
>
> Acked-by: Martin Schwidefsky <schwidefsky@...ibm.com>
> Signed-off-by: Gerald Schaefer <gerald.schaefer@...ibm.com>
> ---
>
>  mm/hugetlb.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> Index: linux/mm/hugetlb.c
> ===================================================================
> --- linux.orig/mm/hugetlb.c
> +++ linux/mm/hugetlb.c
> @@ -565,7 +565,7 @@ static struct page *alloc_fresh_huge_pag
>  		huge_page_order(h));
>  	if (page) {
>  		if (arch_prepare_hugepage(page)) {
> -			__free_pages(page, HUGETLB_PAGE_ORDER);
> +			__free_pages(page, huge_page_order(h));
>  			return NULL;
>  		}
>  		prep_new_huge_page(h, page, nid);

This looks like a seperate bugfix?


> @@ -665,6 +665,11 @@ static struct page *alloc_buddy_huge_pag
>  					__GFP_REPEAT|__GFP_NOWARN,
>  					huge_page_order(h));
>
> +	if (page && arch_prepare_hugepage(page)) {
> +		__free_pages(page, huge_page_order(h));
> +		return NULL;
> +	}
> +
>  	spin_lock(&hugetlb_lock);
>  	if (page) {
>  		/*

Acked-by: Nick Piggin <npiggin@...e.de>
--
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