Re: [PATCH] [MIPS] Hibernation: only save pages in system ram

[Wu Zhangjin <wuzhangjin@gmail.com>]

On Fri, 2009-07-03 at 00:22 +0100, Ralf Baechle wrote:
> On Tue, Jun 30, 2009 at 10:52:50PM +0800, Wu Zhangjin wrote:
> 
> > From: Wu Zhangjin <wuzj@lemote.com>
> > 
> > when using hibernation(STD) with CONFIG_FLATMEM in linux-mips-64bit, it
> > fails for the current mips-specific hibernation implementation save the
> > pages in all of the memory space(except the nosave section) and make
> > there will be not enough memory left to the STD task itself, and then
> > fail. in reality, we only need to save the pages in system rams.
> > 
> > here is the reason why it fail:
> > 
> > kernel/power/snapshot.c:
> > 
> > static void mark_nosave_pages(struct memory_bitmap *bm)
> > {
> > 		...
> > 		if (pfn_valid(pfn)) {
> > 			...
> > 		}
> > }
> > 
> > arch/mips/include/asm/page.h:
> > 
> > 	...
> > 	#ifdef CONFIG_FLATMEM
> > 
> > 	#define pfn_valid(pfn)		((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
> > 
> > 	#elif defined(CONFIG_SPARSEMEM)
> > 
> > 	/* pfn_valid is defined in linux/mmzone.h */
> > 	...
> > 
> > we can rewrite pfn_valid(pfn) to fix this problem, but I really do not
> > want to touch such a widely-used macro, so, I used another solution:
> > 
> > static struct page *saveable_page(struct zone *zone, unsigned long pfn)
> > {
> > 	...
> > 	if ( .... pfn_is_nosave(pfn)
> > 		return NULL;
> > 	...
> > }
> > 
> > and pfn_is_nosave is implemented in arch/mips/power/cpu.c, so, hacking
> > this one is better.
> 
> No - pfn_valid() is broken, so it should be fixed.  Commit
> 752fbeb2e3555c0d236e992f1195fd7ce30e728d introduced the breakage.  It
> seemed to assume that the valid range for PFNs doesn't start at 0 but
> some higher number but got that entirely wrong..
> 
> #define ARCH_PFN_OFFSET         PFN_UP(PHYS_OFFSET)
> #define pfn_valid(pfn)         ((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
> 
> works nicely when PHYS_OFFSET is 0 - as for most MIPS systems and goes
> horribly wrong otherwise.  So I suggest below patch.

Just test it with the latest master branch of linux-mips on fulong2e,
Your patch works well, thanks!

(BTW: of course, the ide-relative bug is also there even with Bart's
patch, so, currently, I just revert this part of the ide patch: "ide:
improve handling of Power Management requests" to test your patch: 

diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index d5f3c77..8c4608c 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -468,12 +468,12 @@ void do_ide_request(struct request_queue *q)
                ide_hwif_t *prev_port;
 repeat:
                prev_port = hwif->host->cur_port;
-
+/*
                if (drive->dev_flags & IDE_DFLAG_BLOCKED)
                        rq = hwif->rq;
                else
                        WARN_ON_ONCE(hwif->rq);
-
+*/
                if (drive->dev_flags & IDE_DFLAG_SLEEPING &&
                    time_after(drive->sleep, jiffies)) {
                        ide_unlock_port(hwif);

So, I will try to test Bart's patch with linux-next, I'm cloning it
currently! perhaps there is something missing in my git repo or the
linux-mips git repo? because i can not apply bart's patch neither to my
git repo nor to the master branch of linux-mips git repo directly, even
if pulled linux-next and Davie's ide-2.6 in.
)

Regards,
Wu Zhangjin

> 
>   Ralf
> 
> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
> 
>  arch/mips/include/asm/page.h |    9 ++++++++-
>  1 files changed, 8 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
> index dc0eaa7..96a14a4 100644
> --- a/arch/mips/include/asm/page.h
> +++ b/arch/mips/include/asm/page.h
> @@ -165,7 +165,14 @@ typedef struct { unsigned long pgprot; } pgprot_t;
>  
>  #ifdef CONFIG_FLATMEM
>  
> -#define pfn_valid(pfn)		((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
> +#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;			\
> +})
>  
>  #elif defined(CONFIG_SPARSEMEM)
>