[PATCH] testSigned-off-by: MinChan Kim <minchan.kim@gmail.com>

[MinChan Kim]

---
 include/linux/pagemap.h |    9 ---------
 include/linux/swap.h    |    9 ++-------
 2 files changed, 2 insertions(+), 16 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 4d27bf8..0cf024c 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -32,7 +32,6 @@ static inline void mapping_set_error(struct address_space *mapping, int error)
 	}
 }
 
-#ifdef CONFIG_UNEVICTABLE_LRU
 #define AS_UNEVICTABLE	(__GFP_BITS_SHIFT + 2)	/* e.g., ramdisk, SHM_LOCK */
 
 static inline void mapping_set_unevictable(struct address_space *mapping)
@@ -51,14 +50,6 @@ static inline int mapping_unevictable(struct address_space *mapping)
 		return test_bit(AS_UNEVICTABLE, &mapping->flags);
 	return !!mapping;
 }
-#else
-static inline void mapping_set_unevictable(struct address_space *mapping) { }
-static inline void mapping_clear_unevictable(struct address_space *mapping) { }
-static inline int mapping_unevictable(struct address_space *mapping)
-{
-	return 0;
-}
-#endif
 
 static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
 {
diff --git a/include/linux/swap.h b/include/linux/swap.h
index a3af95b..18c639b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -233,8 +233,9 @@ static inline int zone_reclaim(struct zone *z, gfp_t mask, unsigned int order)
 }
 #endif
 
-#ifdef CONFIG_UNEVICTABLE_LRU
 extern int page_evictable(struct page *page, struct vm_area_struct *vma);
+
+#ifdef CONFIG_UNEVICTABLE_LRU
 extern void scan_mapping_unevictable_pages(struct address_space *);
 
 extern unsigned long scan_unevictable_pages;
@@ -243,12 +244,6 @@ extern int scan_unevictable_handler(struct ctl_table *, int, struct file *,
 extern int scan_unevictable_register_node(struct node *node);
 extern void scan_unevictable_unregister_node(struct node *node);
 #else
-static inline int page_evictable(struct page *page,
-						struct vm_area_struct *vma)
-{
-	return 1;
-}
-
 static inline void scan_mapping_unevictable_pages(struct address_space *mapping)
 {
 }
-- 
1.5.4.3



> On Thu, 12 Mar 2009 10:04:41 +0900 (JST)
> KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>
> Hi
> 
> > >> Page reclaim shouldn't be even attempting to reclaim or write back
> > >> ramfs pagecache pages - reclaim can't possibly do anything with these
> > >> pages!
> > >>
> > >> Arguably those pages shouldn't be on the LRU at all, but we haven't
> > >> done that yet.
> > >>
> > >> Now, my problem is that I can't 100% be sure that we _ever_ implemented
> > >> this properly. ?I _think_ we did, in which case we later broke it. ?If
> > >> we've always been (stupidly) trying to pageout these pages then OK, I
> > >> guess your patch is a suitable 2.6.29 stopgap.
> > >
> > > OK, I can't find any code anywhere in which we excluded ramfs pages
> > > from consideration by page reclaim. ?How dumb.
> > 
> > The ramfs  considers it in just CONFIG_UNEVICTABLE_LRU case
> > It that case, ramfs_get_inode calls mapping_set_unevictable.
> > So,  page reclaim can exclude ramfs pages by page_evictable.
> > It's problem .
> 
> Currently, CONFIG_UNEVICTABLE_LRU can't use on nommu machine
> because nobody of vmscan folk havbe nommu machine.
> 
> Yes, it is very stupid reason. _very_ welcome to tester! :)
> 
> 
> 
> David, Could you please try following patch if you have NOMMU machine?
> it is straightforward porting to nommu.
> 
> 
> ==
> Subject: [PATCH] remove to depend on MMU from CONFIG_UNEVICTABLE_LRU
> 
> logically, CONFIG_UNEVICTABLE_LRU doesn't depend on MMU.
> but current code does by mistake. fix it.
> 
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> ---
>  mm/Kconfig |    1 -
>  mm/nommu.c |   24 ++++++++++++++++++++++++
>  2 files changed, 24 insertions(+), 1 deletion(-)
> 
> Index: b/mm/Kconfig
> ===================================================================
> --- a/mm/Kconfig	2008-12-28 20:55:23.000000000 +0900
> +++ b/mm/Kconfig	2008-12-28 21:24:08.000000000 +0900
> @@ -212,7 +212,6 @@ config VIRT_TO_BUS
>  config UNEVICTABLE_LRU
>  	bool "Add LRU list to track non-evictable pages"
>  	default y
> -	depends on MMU
>  	help
>  	  Keeps unevictable pages off of the active and inactive pageout
>  	  lists, so kswapd will not waste CPU time or have its balancing
> Index: b/mm/nommu.c
> ===================================================================
> --- a/mm/nommu.c	2008-12-25 08:26:37.000000000 +0900
> +++ b/mm/nommu.c	2008-12-28 21:29:36.000000000 +0900
> @@ -1521,3 +1521,27 @@ int access_process_vm(struct task_struct
>  	mmput(mm);
>  	return len;
>  }
> +
> +/*
> + *  LRU accounting for clear_page_mlock()
> + */
> +void __clear_page_mlock(struct page *page)
> +{
> +	VM_BUG_ON(!PageLocked(page));
> +
> +	if (!page->mapping) {	/* truncated ? */
> +		return;
> +	}
> +
> +	dec_zone_page_state(page, NR_MLOCK);
> +	count_vm_event(UNEVICTABLE_PGCLEARED);
> +	if (!isolate_lru_page(page)) {
> +		putback_lru_page(page);
> +	} else {
> +		/*
> +		 * We lost the race. the page already moved to evictable list.
> +		 */
> +		if (PageUnevictable(page))
> +			count_vm_event(UNEVICTABLE_PGSTRANDED);
> +	}
> +}
> 
> 
> 
> 


-- 
Kinds Regards
Minchan Kim
--
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