Export swapper_space

Export swapper_space

[Russell King]

swapper_space appears to be needed by modules:

  Building modules, stage 2.
  MODPOST
*** Warning: "swapper_space" [drivers/block/loop.ko] undefined!
*** Warning: "swapper_space" [drivers/scsi/st.ko] undefined!
*** Warning: "swapper_space" [drivers/scsi/sg.ko] undefined!

--- orig/mm/swap_state.c	Mon May 24 11:26:25 2004
+++ linux/mm/swap_state.c	Thu Jun  3 16:11:58 2004
@@ -6,7 +6,7 @@
  *
  *  Rewritten to use page cache, (C) 1998 Stephen Tweedie
  */
-
+#include <linux/module.h>
 #include <linux/mm.h>
 #include <linux/kernel_stat.h>
 #include <linux/swap.h>
@@ -38,6 +38,7 @@ struct address_space swapper_space = {
 	.a_ops		= &swap_aops,
 	.backing_dev_info = &swap_backing_dev_info,
 };
+EXPORT_SYMBOL(swapper_space);
 
 #define INC_CACHE_INFO(x)	do { swap_cache_info.x++; } while (0)
 

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

Re: Export swapper_space

[Christoph Hellwig]

On Thu, Jun 03, 2004 at 04:19:10PM +0100, Russell King wrote:
> swapper_space appears to be needed by modules:
> 
>   Building modules, stage 2.
>   MODPOST
> *** Warning: "swapper_space" [drivers/block/loop.ko] undefined!
> *** Warning: "swapper_space" [drivers/scsi/st.ko] undefined!
> *** Warning: "swapper_space" [drivers/scsi/sg.ko] undefined!

Please not.  This seems to be some cache-flushing magic on the stranger
architectures again :)  Can you check how they're using it in the end
and hopefully fix it by uninlining something?

Re: Export swapper_space

[Russell King]

On Thu, Jun 03, 2004 at 04:37:27PM +0100, Christoph Hellwig wrote:
> On Thu, Jun 03, 2004 at 04:19:10PM +0100, Russell King wrote:
> > swapper_space appears to be needed by modules:
> > 
> >   Building modules, stage 2.
> >   MODPOST
> > *** Warning: "swapper_space" [drivers/block/loop.ko] undefined!
> > *** Warning: "swapper_space" [drivers/scsi/st.ko] undefined!
> > *** Warning: "swapper_space" [drivers/scsi/sg.ko] undefined!
> 
> Please not.  This seems to be some cache-flushing magic on the stranger
> architectures again :)  Can you check how they're using it in the end
> and hopefully fix it by uninlining something?

extern struct address_space swapper_space;
static inline struct address_space *page_mapping(struct page *page)
{
        struct address_space *mapping = NULL;
 
        if (unlikely(PageSwapCache(page)))
                mapping = &swapper_space;
        else if (likely(!PageAnon(page)))
                mapping = page->mapping;
        return mapping;
}

I'll leave that for someone else to sort out.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core

Re: Export swapper_space

[Andrew Morton]

Russell King <rmk+lkml@arm.linux.org.uk> wrote:
>
> > Please not.  This seems to be some cache-flushing magic on the stranger
>  > architectures again :)  Can you check how they're using it in the end
>  > and hopefully fix it by uninlining something?
> 
>  extern struct address_space swapper_space;
>  static inline struct address_space *page_mapping(struct page *page)
>  {
>          struct address_space *mapping = NULL;
>   
>          if (unlikely(PageSwapCache(page)))
>                  mapping = &swapper_space;
>          else if (likely(!PageAnon(page)))
>                  mapping = page->mapping;
>          return mapping;
>  }

Christoph means "can arm uninline flush_dcache_page()"?

It looks like that would be the best approach - it's quite a large function.

Re: Export swapper_space

[Russell King]

On Thu, Jun 03, 2004 at 10:08:26AM -0700, Andrew Morton wrote:
> Christoph means "can arm uninline flush_dcache_page()"?
> 
> It looks like that would be the best approach - it's quite a large function.

Grumble.  We could, though I didn't expect it to become a large
function...  I guess the bloat monster has been fed again. ;(

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                 2.6 Serial core