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

To: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH] MIPS: fix pfn_valid() for FLAGMEM
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Thu, 08 Oct 2009 18:33:39 +0800
Cc: linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>, "Rafael J. Wysocki" <rjw@sisk.pl>
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In-reply-to: <20091008092903.GA27054@elf.ucw.cz>
Organization: DSLab, Lanzhou University, China
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1254992252-15923-1-git-send-email-wuzhangjin@gmail.com> <20091008092903.GA27054@elf.ucw.cz>
Reply-to: wuzhangjin@gmail.com
Sender: linux-mips-bounce@linux-mips.org
Hi,

On Thu, 2009-10-08 at 11:29 +0200, Pavel Machek wrote:
> 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?
> 

Perhaps need to move the whole "#ifdef CONFIG_FLATMEM" to #ifndef
ASSEMBLY, otherwise,

"arch/mips/include/asm/page.h:170: Error: unrecognized opcode `extern
int pfn_valid(unsigned long)'". 

Regards,
        Wu Zhangjin


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