linux-kernel - Re: [RFC 2/3] PM / Hibernate : do not count debug pages as savable

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Date:	Tue, 18 Oct 2011 00:16:26 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Mel Gorman <mgorman@...e.de>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [RFC 2/3] PM / Hibernate : do not count debug pages as savable

On Monday, October 17, 2011, Stanislaw Gruszka wrote:
> When debugging memory corruption with CONFIG_DEBUG_PAGEALLOC and
> corrupt_dbg > 0, we have lot of free pages that are not marked so.
> Snapshot code account them as savable, what cause hibernate memory
> preallocation failure.
> 
> It is pretty hard to make hibernate allocation succeed with
> corrupt_dbg=1. This change at least make it possible when system has
> relatively big amount of RAM.
> 
> Signed-off-by: Stanislaw Gruszka <sgruszka@...hat.com>

Acked-by: Rafael J. Wysocki <rjw@...k.pl>

> ---
>  include/linux/mm.h      |    7 ++++++-
>  kernel/power/snapshot.c |    6 ++++++
>  mm/page_alloc.c         |    6 ------
>  3 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 17e3658..651785b 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1630,13 +1630,18 @@ extern void copy_user_huge_page(struct page *dst, struct page *src,
>  #ifdef CONFIG_DEBUG_PAGEALLOC
>  extern unsigned int _corrupt_dbg;
>  
> -
>  static inline unsigned int corrupt_dbg(void)
>  {
>  	return _corrupt_dbg;
>  }
> +
> +static inline bool page_is_corrupt_dbg(struct page *page)
> +{
> +	return test_bit(PAGE_DEBUG_FLAG_CORRUPT, &page->debug_flags);
> +}
>  #else
>  static inline unsigned int corrupt_dbg(void) { return 0; }
> +static inline bool page_is_corrupt_dbg(struct page *page) { return false; }
>  #endif /* CONFIG_DEBUG_PAGEALLOC */
>  
>  #endif /* __KERNEL__ */
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 06efa54..45cf1b1 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -858,6 +858,9 @@ static struct page *saveable_highmem_page(struct zone *zone, unsigned long pfn)
>  	    PageReserved(page))
>  		return NULL;
>  
> +	if (page_is_corrupt_dbg(page))
> +		return NULL;
> +
>  	return page;
>  }
>  
> @@ -920,6 +923,9 @@ static struct page *saveable_page(struct zone *zone, unsigned long pfn)
>  	    && (!kernel_page_present(page) || pfn_is_nosave(pfn)))
>  		return NULL;
>  
> +	if (page_is_corrupt_dbg(page))
> +		return NULL;
> +
>  	return page;
>  }
>  
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8d18ae4..8a7770a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -425,15 +425,9 @@ static inline void clear_page_corrupt_dbg(struct page *page)
>  	__clear_bit(PAGE_DEBUG_FLAG_CORRUPT, &page->debug_flags);
>  }
>  
> -static inline bool page_is_corrupt_dbg(struct page *page)
> -{
> -	return test_bit(PAGE_DEBUG_FLAG_CORRUPT, &page->debug_flags);
> -}
> -
>  #else
>  static inline void set_page_corrupt_dbg(struct page *page) { }
>  static inline void clear_page_corrupt_dbg(struct page *page) { }
> -static inline bool page_is_corrupt_dbg(struct page *page) { return false; }
>  #endif
>  
>  static inline void set_page_order(struct page *page, int order)
> 

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