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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 12:36:14 +0200
Cc: linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>, "Rafael J. Wysocki" <rjw@sisk.pl>
In-reply-to: <1254998019.14496.21.camel@falcon>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1254992252-15923-1-git-send-email-wuzhangjin@gmail.com> <20091008092903.GA27054@elf.ucw.cz> <1254998019.14496.21.camel@falcon>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.5.18 (2008-05-17)
On Thu 2009-10-08 18:33:39, Wu Zhangjin wrote:
> 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)'". 

I guess so. pfn_valid() will not work from assembly, anywa, so...
                                                                        Pavel

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