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Re: [PATCH] MIPS: fix pfn_valid() for FLAGMEM

To: Wu Zhangjin <wuzhangjin@gmail.com>
Subject: Re: [PATCH] MIPS: fix pfn_valid() for FLAGMEM
From: Pavel Machek <pavel@ucw.cz>
Date: Thu, 8 Oct 2009 11:29:03 +0200
Cc: linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>, "Rafael J. Wysocki" <rjw@sisk.pl>
In-reply-to: <1254992252-15923-1-git-send-email-wuzhangjin@gmail.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1254992252-15923-1-git-send-email-wuzhangjin@gmail.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
On Thu 2009-10-08 16:57:32, Wu Zhangjin wrote:
> When CONFIG_FLAGMEM enabled, STD/Hiberation will fail on YeeLoong
> laptop, This patch fix it:
> 
> if pfn is between min_low_pfn and max_mapnr, the old pfn_valid() will
> return TRUE, but in reality, if the memory is not continuous, it should
> be false. for example:
> 
> $ cat /proc/iomem | grep "System RAM"
> 00000000-0fffffff : System RAM
> 90000000-bfffffff : System RAM
> 
> as we can see, it is not continuous, so, some of the memory is not valid
> but regarded as valid by pfn_valid(), and at last make STD/Hibernate
> fail when shrinking a too large number of invalid memory.
> 
> Here, we fix it via checking pfn is in the "System RAM" or not, if yes,
> return TRUE.

"return FALSE"?

> Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>

Looks mostly ok, small comments below. 

> @@ -168,13 +168,10 @@ typedef struct { unsigned long pgprot; } pgprot_t;
>  
>  #ifdef CONFIG_FLATMEM
>  
> -#define pfn_valid(pfn)                                                       
> \
> -({                                                                   \
> -     unsigned long __pfn = (pfn);                                    \
> -     /* avoid <linux/bootmem.h> include hell */                      \
> -     extern unsigned long min_low_pfn;                               \
> -                                                                     \
> -     __pfn >= min_low_pfn && __pfn < max_mapnr;                      \
> +#define pfn_valid(pfn)                               \
> +({                                           \
> +     extern int is_pfn_valid(unsigned long); \
> +     is_pfn_valid(pfn);                      \
>  })

"extern int pfn_valid here"

...and get away without the ugly macro?

>  #elif defined(CONFIG_SPARSEMEM)
> diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c
> index f5c7375..48a4d2a 100644
> --- a/arch/mips/mm/page.c
> +++ b/arch/mips/mm/page.c
> @@ -689,3 +689,20 @@ void copy_page(void *to, void *from)
>  }
>  
>  #endif /* CONFIG_SIBYTE_DMA_PAGEOPS */
> +
> +#ifdef CONFIG_FLATMEM
> +int is_pfn_valid(unsigned long pfn)

...with simple function rename?
                                                                        Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) 
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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