[PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

[PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

[Hillf Danton]

From: Hillf Danton <dhillf@gmail.com>
Subject: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

If we have to hand back the newly allocated huge page to page allocator,
for any reason, the changed counter should be recovered.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Hillf Danton <dhillf@gmail.com>
---

--- a/mm/hugetlb.c	Tue Dec 20 21:26:30 2011
+++ b/mm/hugetlb.c	Fri Dec 23 21:18:06 2011
@@ -800,7 +800,7 @@ static struct page *alloc_buddy_huge_pag

 	if (page && arch_prepare_hugepage(page)) {
 		__free_pages(page, huge_page_order(h));
-		return NULL;
+		page = NULL;
 	}

 	spin_lock(&hugetlb_lock);

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Re: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

[KAMEZAWA Hiroyuki]

On Fri, 23 Dec 2011 21:38:38 +0800
Hillf Danton <dhillf@gmail.com> wrote:

> From: Hillf Danton <dhillf@gmail.com>
> Subject: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page
> 
> If we have to hand back the newly allocated huge page to page allocator,
> for any reason, the changed counter should be recovered.
> 
> Cc: Michal Hocko <mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

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Re: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

[Michal Hocko]

On Fri 23-12-11 21:38:38, Hillf Danton wrote:
> From: Hillf Danton <dhillf@gmail.com>
> Subject: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page
> 
> If we have to hand back the newly allocated huge page to page allocator,
> for any reason, the changed counter should be recovered.
> 
> Cc: Michal Hocko <mhocko@suse.cz>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>

Broken since 2.6.27 (caff3a2c: hugetlb: call arch_prepare_hugepage() for
surplus pages) so a stable material

Reviewed-by: Michal Hocko <mhocko@suse.cz>

Thanks
> ---
> 
> --- a/mm/hugetlb.c	Tue Dec 20 21:26:30 2011
> +++ b/mm/hugetlb.c	Fri Dec 23 21:18:06 2011
> @@ -800,7 +800,7 @@ static struct page *alloc_buddy_huge_pag
> 
>  	if (page && arch_prepare_hugepage(page)) {
>  		__free_pages(page, huge_page_order(h));
> -		return NULL;
> +		page = NULL;
>  	}
> 
>  	spin_lock(&hugetlb_lock);
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-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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Re: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page

[Andrew Morton]

On Tue, 27 Dec 2011 13:57:01 +0100
Michal Hocko <mhocko@suse.cz> wrote:

> On Fri 23-12-11 21:38:38, Hillf Danton wrote:
> > From: Hillf Danton <dhillf@gmail.com>
> > Subject: [PATCH] mm: hugetlb: avoid bogus counter of surplus huge page
> > 
> > If we have to hand back the newly allocated huge page to page allocator,
> > for any reason, the changed counter should be recovered.
> > 
> > Cc: Michal Hocko <mhocko@suse.cz>
> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Signed-off-by: Hillf Danton <dhillf@gmail.com>
> 
> Broken since 2.6.27 (caff3a2c: hugetlb: call arch_prepare_hugepage() for
> surplus pages) so a stable material

afacit only s390 is affected, and s390's page_table_alloc() is fairly
immortal, using GFP_KERNEL|__GFP_REPEAT.

So unless Martin and Heiko disagree, I think we can merge this in 3.3-rc1.

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