[PATCH v1 00/10] make try_to_unmap simple

[PATCH v1 00/10] make try_to_unmap simple

[Minchan Kim]

Currently, try_to_unmap returns various return value(SWAP_SUCCESS,
SWAP_FAIL, SWAP_AGAIN, SWAP_DIRTY and SWAP_MLOCK). When I look into
that, it's unncessary complicated so this patch aims for cleaning
it up. Change ttu to boolean function so we can remove SWAP_AGAIN,
SWAP_DIRTY, SWAP_MLOCK.

* from RFC
- http://lkml.kernel.org/r/1488436765-32350-1-git-send-email-minchan@kernel.org
  * Remove RFC tag
  * add acked-by to some patches
  * some of minor fixes
  * based on mmotm-2017-03-09-16-19.

Minchan Kim (10):
  mm: remove unncessary ret in page_referenced
  mm: remove SWAP_DIRTY in ttu
  mm: remove SWAP_MLOCK check for SWAP_SUCCESS in ttu
  mm: make the try_to_munlock void function
  mm: remove SWAP_MLOCK in ttu
  mm: remove SWAP_AGAIN in ttu
  mm: make ttu's return boolean
  mm: make rmap_walk void function
  mm: make rmap_one boolean function
  mm: remove SWAP_[SUCCESS|AGAIN|FAIL]

 include/linux/ksm.h  |   5 ++-
 include/linux/rmap.h |  21 ++++-------
 mm/huge_memory.c     |   6 ++--
 mm/ksm.c             |  16 ++++-----
 mm/memory-failure.c  |  26 +++++++-------
 mm/migrate.c         |   4 +--
 mm/mlock.c           |   6 ++--
 mm/page_idle.c       |   4 +--
 mm/rmap.c            | 100 ++++++++++++++++++++-------------------------------
 mm/vmscan.c          |  32 +++++------------
 10 files changed, 82 insertions(+), 138 deletions(-)

-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 01/10] mm: remove unncessary ret in page_referenced

[Minchan Kim]

Anyone doesn't use ret variable. Remove it.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/rmap.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 7d24bb9..9dbfa6f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -807,7 +807,6 @@ int page_referenced(struct page *page,
 		    struct mem_cgroup *memcg,
 		    unsigned long *vm_flags)
 {
-	int ret;
 	int we_locked = 0;
 	struct page_referenced_arg pra = {
 		.mapcount = total_mapcount(page),
@@ -841,7 +840,7 @@ int page_referenced(struct page *page,
 		rwc.invalid_vma = invalid_page_referenced_vma;
 	}
 
-	ret = rmap_walk(page, &rwc);
+	rmap_walk(page, &rwc);
 	*vm_flags = pra.vm_flags;
 
 	if (we_locked)
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v1 01/10] mm: remove unncessary ret in page_referenced

[Hillf Danton]

On March 13, 2017 8:36 AM Minchan Kim wrote: 
> 
> Anyone doesn't use ret variable. Remove it.
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>


>  mm/rmap.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 7d24bb9..9dbfa6f 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -807,7 +807,6 @@ int page_referenced(struct page *page,
>  		    struct mem_cgroup *memcg,
>  		    unsigned long *vm_flags)
>  {
> -	int ret;
>  	int we_locked = 0;
>  	struct page_referenced_arg pra = {
>  		.mapcount = total_mapcount(page),
> @@ -841,7 +840,7 @@ int page_referenced(struct page *page,
>  		rwc.invalid_vma = invalid_page_referenced_vma;
>  	}
> 
> -	ret = rmap_walk(page, &rwc);
> +	rmap_walk(page, &rwc);
>  	*vm_flags = pra.vm_flags;
> 
>  	if (we_locked)
> --
> 2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 02/10] mm: remove SWAP_DIRTY in ttu

[Minchan Kim]

If we found lazyfree page is dirty, try_to_unmap_one can just
SetPageSwapBakced in there like PG_mlocked page and just return
with SWAP_FAIL which is very natural because the page is not
swappable right now so that vmscan can activate it.
There is no point to introduce new return value SWAP_DIRTY
in ttu at the moment.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h | 1 -
 mm/rmap.c            | 6 +++---
 mm/vmscan.c          | 3 ---
 3 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index fee10d7..b556eef 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -298,6 +298,5 @@ static inline int page_mkclean(struct page *page)
 #define SWAP_AGAIN	1
 #define SWAP_FAIL	2
 #define SWAP_MLOCK	3
-#define SWAP_DIRTY	4
 
 #endif	/* _LINUX_RMAP_H */
diff --git a/mm/rmap.c b/mm/rmap.c
index 9dbfa6f..d47af09 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1414,7 +1414,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 			 */
 			if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
 				WARN_ON_ONCE(1);
-				ret = SWAP_FAIL;
+				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1431,7 +1431,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				 * discarded. Remap the page to page table.
 				 */
 				set_pte_at(mm, address, pvmw.pte, pteval);
-				ret = SWAP_DIRTY;
+				SetPageSwapBacked(page);
+				ret = SWAP_FAIL;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1501,7 +1502,6 @@ static int page_mapcount_is_zero(struct page *page)
  * SWAP_AGAIN	- we missed a mapping, try again later
  * SWAP_FAIL	- the page is unswappable
  * SWAP_MLOCK	- page is mlocked.
- * SWAP_DIRTY	- page is dirty MADV_FREE page
  */
 int try_to_unmap(struct page *page, enum ttu_flags flags)
 {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index a3656f9..b8fd656 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1142,9 +1142,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		if (page_mapped(page)) {
 			switch (ret = try_to_unmap(page,
 				ttu_flags | TTU_BATCH_FLUSH)) {
-			case SWAP_DIRTY:
-				SetPageSwapBacked(page);
-				/* fall through */
 			case SWAP_FAIL:
 				nr_unmap_fail++;
 				goto activate_locked;
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v1 02/10] mm: remove SWAP_DIRTY in ttu

[Hillf Danton]

On March 13, 2017 8:36 AM Minchan Kim wrote: 
> 
> If we found lazyfree page is dirty, try_to_unmap_one can just
> SetPageSwapBakced in there like PG_mlocked page and just return
> with SWAP_FAIL which is very natural because the page is not
> swappable right now so that vmscan can activate it.
> There is no point to introduce new return value SWAP_DIRTY
> in ttu at the moment.
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

>  include/linux/rmap.h | 1 -
>  mm/rmap.c            | 6 +++---
>  mm/vmscan.c          | 3 ---
>  3 files changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index fee10d7..b556eef 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -298,6 +298,5 @@ static inline int page_mkclean(struct page *page)
>  #define SWAP_AGAIN	1
>  #define SWAP_FAIL	2
>  #define SWAP_MLOCK	3
> -#define SWAP_DIRTY	4
> 
>  #endif	/* _LINUX_RMAP_H */
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 9dbfa6f..d47af09 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1414,7 +1414,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  			 */
>  			if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
>  				WARN_ON_ONCE(1);
> -				ret = SWAP_FAIL;
> +				ret = false;
Nit:
Hm looks like stray merge.
Not sure it's really needed. 

>  				page_vma_mapped_walk_done(&pvmw);
>  				break;
>  			}
> @@ -1431,7 +1431,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  				 * discarded. Remap the page to page table.
>  				 */
>  				set_pte_at(mm, address, pvmw.pte, pteval);
> -				ret = SWAP_DIRTY;
> +				SetPageSwapBacked(page);
> +				ret = SWAP_FAIL;
>  				page_vma_mapped_walk_done(&pvmw);
>  				break;
>  			}
> @@ -1501,7 +1502,6 @@ static int page_mapcount_is_zero(struct page *page)
>   * SWAP_AGAIN	- we missed a mapping, try again later
>   * SWAP_FAIL	- the page is unswappable
>   * SWAP_MLOCK	- page is mlocked.
> - * SWAP_DIRTY	- page is dirty MADV_FREE page
>   */
>  int try_to_unmap(struct page *page, enum ttu_flags flags)
>  {
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a3656f9..b8fd656 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1142,9 +1142,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>  		if (page_mapped(page)) {
>  			switch (ret = try_to_unmap(page,
>  				ttu_flags | TTU_BATCH_FLUSH)) {
> -			case SWAP_DIRTY:
> -				SetPageSwapBacked(page);
> -				/* fall through */
>  			case SWAP_FAIL:
>  				nr_unmap_fail++;
>  				goto activate_locked;
> --
> 2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v1 02/10] mm: remove SWAP_DIRTY in ttu

[Minchan Kim]

Hello Hillf,

On Mon, Mar 13, 2017 at 02:34:37PM +0800, Hillf Danton wrote:
> 
> On March 13, 2017 8:36 AM Minchan Kim wrote: 
> > 
> > If we found lazyfree page is dirty, try_to_unmap_one can just
> > SetPageSwapBakced in there like PG_mlocked page and just return
> > with SWAP_FAIL which is very natural because the page is not
> > swappable right now so that vmscan can activate it.
> > There is no point to introduce new return value SWAP_DIRTY
> > in ttu at the moment.
> > 
> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> > ---
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> 
> >  include/linux/rmap.h | 1 -
> >  mm/rmap.c            | 6 +++---
> >  mm/vmscan.c          | 3 ---
> >  3 files changed, 3 insertions(+), 7 deletions(-)
> > 
> > diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> > index fee10d7..b556eef 100644
> > --- a/include/linux/rmap.h
> > +++ b/include/linux/rmap.h
> > @@ -298,6 +298,5 @@ static inline int page_mkclean(struct page *page)
> >  #define SWAP_AGAIN	1
> >  #define SWAP_FAIL	2
> >  #define SWAP_MLOCK	3
> > -#define SWAP_DIRTY	4
> > 
> >  #endif	/* _LINUX_RMAP_H */
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 9dbfa6f..d47af09 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -1414,7 +1414,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> >  			 */
> >  			if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
> >  				WARN_ON_ONCE(1);
> > -				ret = SWAP_FAIL;
> > +				ret = false;
> Nit:
> Hm looks like stray merge.
> Not sure it's really needed. 

rebase fail ;-O

Thanks!

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 03/10] mm: remove SWAP_MLOCK check for SWAP_SUCCESS in ttu

[Minchan Kim]

If the page is mapped and rescue in try_to_unmap_one,
page_mapcount(page) == 0 cannot be true so page_mapcount check
in try_to_unmap is enough to return SWAP_SUCCESS.
IOW, SWAP_MLOCK check is redundant so remove it.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/rmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index d47af09..1cfb3a3 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1530,7 +1530,7 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
 	else
 		ret = rmap_walk(page, &rwc);
 
-	if (ret != SWAP_MLOCK && !page_mapcount(page))
+	if (!page_mapcount(page))
 		ret = SWAP_SUCCESS;
 	return ret;
 }
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 04/10] mm: make the try_to_munlock void function

[Minchan Kim]

try_to_munlock returns SWAP_MLOCK if the one of VMAs mapped
the page has VM_LOCKED flag. In that time, VM set PG_mlocked to
the page if the page is not pte-mapped THP which cannot be
mlocked, either.

With that, __munlock_isolated_page can use PageMlocked to check
whether try_to_munlock is successful or not without relying on
try_to_munlock's retval. It helps to make try_to_unmap/try_to_unmap_one
simple with upcoming patches.

Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h |  2 +-
 mm/mlock.c           |  6 ++----
 mm/rmap.c            | 17 +++++------------
 3 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index b556eef..1b0cd4c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -235,7 +235,7 @@ int page_mkclean(struct page *);
  * called in munlock()/munmap() path to check for other vmas holding
  * the page mlocked.
  */
-int try_to_munlock(struct page *);
+void try_to_munlock(struct page *);
 
 void remove_migration_ptes(struct page *old, struct page *new, bool locked);
 
diff --git a/mm/mlock.c b/mm/mlock.c
index 02f1382..9660ee5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -123,17 +123,15 @@ static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
  */
 static void __munlock_isolated_page(struct page *page)
 {
-	int ret = SWAP_AGAIN;
-
 	/*
 	 * Optimization: if the page was mapped just once, that's our mapping
 	 * and we don't need to check all the other vmas.
 	 */
 	if (page_mapcount(page) > 1)
-		ret = try_to_munlock(page);
+		try_to_munlock(page);
 
 	/* Did try_to_unlock() succeed or punt? */
-	if (ret != SWAP_MLOCK)
+	if (!PageMlocked(page))
 		count_vm_event(UNEVICTABLE_PGMUNLOCKED);
 
 	putback_lru_page(page);
diff --git a/mm/rmap.c b/mm/rmap.c
index 1cfb3a3..9c51065 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1547,18 +1547,10 @@ static int page_not_mapped(struct page *page)
  * Called from munlock code.  Checks all of the VMAs mapping the page
  * to make sure nobody else has this page mlocked. The page will be
  * returned with PG_mlocked cleared if no other vmas have it mlocked.
- *
- * Return values are:
- *
- * SWAP_AGAIN	- no vma is holding page mlocked, or,
- * SWAP_AGAIN	- page mapped in mlocked vma -- couldn't acquire mmap sem
- * SWAP_FAIL	- page cannot be located at present
- * SWAP_MLOCK	- page is now mlocked.
  */
-int try_to_munlock(struct page *page)
-{
-	int ret;
 
+void try_to_munlock(struct page *page)
+{
 	struct rmap_walk_control rwc = {
 		.rmap_one = try_to_unmap_one,
 		.arg = (void *)TTU_MUNLOCK,
@@ -1568,9 +1560,10 @@ int try_to_munlock(struct page *page)
 	};
 
 	VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
+	VM_BUG_ON_PAGE(PageMlocked(page), page);
+	VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
 
-	ret = rmap_walk(page, &rwc);
-	return ret;
+	rmap_walk(page, &rwc);
 }
 
 void __put_anon_vma(struct anon_vma *anon_vma)
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 05/10] mm: remove SWAP_MLOCK in ttu

[Minchan Kim]

ttu don't need to return SWAP_MLOCK. Instead, just return SWAP_FAIL
because it means the page is not-swappable so it should move to
another LRU list(active or unevictable). putback friends will
move it to right list depending on the page's LRU flag.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h |  1 -
 mm/rmap.c            |  3 +--
 mm/vmscan.c          | 20 +++++++-------------
 3 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 1b0cd4c..3630d4d 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -297,6 +297,5 @@ static inline int page_mkclean(struct page *page)
 #define SWAP_SUCCESS	0
 #define SWAP_AGAIN	1
 #define SWAP_FAIL	2
-#define SWAP_MLOCK	3
 
 #endif	/* _LINUX_RMAP_H */
diff --git a/mm/rmap.c b/mm/rmap.c
index 9c51065..38e8ab1 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1324,7 +1324,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 					 */
 					mlock_vma_page(page);
 				}
-				ret = SWAP_MLOCK;
+				ret = SWAP_FAIL;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1501,7 +1501,6 @@ static int page_mapcount_is_zero(struct page *page)
  * SWAP_SUCCESS	- we succeeded in removing all mappings
  * SWAP_AGAIN	- we missed a mapping, try again later
  * SWAP_FAIL	- the page is unswappable
- * SWAP_MLOCK	- page is mlocked.
  */
 int try_to_unmap(struct page *page, enum ttu_flags flags)
 {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b8fd656..2a208f0 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -982,7 +982,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		sc->nr_scanned++;
 
 		if (unlikely(!page_evictable(page)))
-			goto cull_mlocked;
+			goto activate_locked;
 
 		if (!sc->may_unmap && page_mapped(page))
 			goto keep_locked;
@@ -1147,8 +1147,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 				goto activate_locked;
 			case SWAP_AGAIN:
 				goto keep_locked;
-			case SWAP_MLOCK:
-				goto cull_mlocked;
 			case SWAP_SUCCESS:
 				; /* try to free the page below */
 			}
@@ -1290,20 +1288,16 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		list_add(&page->lru, &free_pages);
 		continue;
 
-cull_mlocked:
-		if (PageSwapCache(page))
-			try_to_free_swap(page);
-		unlock_page(page);
-		list_add(&page->lru, &ret_pages);
-		continue;
-
 activate_locked:
 		/* Not a candidate for swapping, so reclaim swap space. */
-		if (PageSwapCache(page) && mem_cgroup_swap_full(page))
+		if (PageSwapCache(page) && (mem_cgroup_swap_full(page) ||
+						PageMlocked(page)))
 			try_to_free_swap(page);
 		VM_BUG_ON_PAGE(PageActive(page), page);
-		SetPageActive(page);
-		pgactivate++;
+		if (!PageMlocked(page)) {
+			SetPageActive(page);
+			pgactivate++;
+		}
 keep_locked:
 		unlock_page(page);
 keep:
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 06/10] mm: remove SWAP_AGAIN in ttu

[Minchan Kim]

In 2002, [1] introduced SWAP_AGAIN.
At that time, try_to_unmap_one used spin_trylock(&mm->page_table_lock)
so it's really easy to contend and fail to hold a lock so SWAP_AGAIN
to keep LRU status makes sense.

However, now we changed it to mutex-based lock and be able to block
without skip pte so there is few of small window to return SWAP_AGAIN
so remove SWAP_AGAIN and just return SWAP_FAIL.

[1] c48c43e, minimal rmap
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/rmap.c   | 11 +++--------
 mm/vmscan.c |  2 --
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 38e8ab1..2a5d854 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1499,13 +1499,10 @@ static int page_mapcount_is_zero(struct page *page)
  * Return values are:
  *
  * SWAP_SUCCESS	- we succeeded in removing all mappings
- * SWAP_AGAIN	- we missed a mapping, try again later
  * SWAP_FAIL	- the page is unswappable
  */
 int try_to_unmap(struct page *page, enum ttu_flags flags)
 {
-	int ret;
-
 	struct rmap_walk_control rwc = {
 		.rmap_one = try_to_unmap_one,
 		.arg = (void *)flags,
@@ -1525,13 +1522,11 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
 		rwc.invalid_vma = invalid_migration_vma;
 
 	if (flags & TTU_RMAP_LOCKED)
-		ret = rmap_walk_locked(page, &rwc);
+		rmap_walk_locked(page, &rwc);
 	else
-		ret = rmap_walk(page, &rwc);
+		rmap_walk(page, &rwc);
 
-	if (!page_mapcount(page))
-		ret = SWAP_SUCCESS;
-	return ret;
+	return !page_mapcount(page) ? SWAP_SUCCESS : SWAP_FAIL;
 }
 
 static int page_not_mapped(struct page *page)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2a208f0..7727fbe 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1145,8 +1145,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 			case SWAP_FAIL:
 				nr_unmap_fail++;
 				goto activate_locked;
-			case SWAP_AGAIN:
-				goto keep_locked;
 			case SWAP_SUCCESS:
 				; /* try to free the page below */
 			}
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 07/10] mm: make ttu's return boolean

[Minchan Kim]

try_to_unmap returns SWAP_SUCCESS or SWAP_FAIL so it's suitable for
boolean return. This patch changes it.

Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h |  4 ++--
 mm/huge_memory.c     |  6 +++---
 mm/memory-failure.c  | 26 ++++++++++++--------------
 mm/rmap.c            |  8 +++-----
 mm/vmscan.c          |  7 +------
 5 files changed, 21 insertions(+), 30 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 3630d4d..6028c38 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -191,7 +191,7 @@ static inline void page_dup_rmap(struct page *page, bool compound)
 int page_referenced(struct page *, int is_locked,
 			struct mem_cgroup *memcg, unsigned long *vm_flags);
 
-int try_to_unmap(struct page *, enum ttu_flags flags);
+bool try_to_unmap(struct page *, enum ttu_flags flags);
 
 /* Avoid racy checks */
 #define PVMW_SYNC		(1 << 0)
@@ -281,7 +281,7 @@ static inline int page_referenced(struct page *page, int is_locked,
 	return 0;
 }
 
-#define try_to_unmap(page, refs) SWAP_FAIL
+#define try_to_unmap(page, refs) false
 
 static inline int page_mkclean(struct page *page)
 {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 2b4120f..033ccee 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2139,15 +2139,15 @@ static void freeze_page(struct page *page)
 {
 	enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
 		TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
-	int ret;
+	bool unmap_success;
 
 	VM_BUG_ON_PAGE(!PageHead(page), page);
 
 	if (PageAnon(page))
 		ttu_flags |= TTU_MIGRATION;
 
-	ret = try_to_unmap(page, ttu_flags);
-	VM_BUG_ON_PAGE(ret, page);
+	unmap_success = try_to_unmap(page, ttu_flags);
+	VM_BUG_ON_PAGE(!unmap_success, page);
 }
 
 static void unfreeze_page(struct page *page)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index f85adfe5..3d3cf6a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -322,7 +322,7 @@ static void add_to_kill(struct task_struct *tsk, struct page *p,
  * wrong earlier.
  */
 static void kill_procs(struct list_head *to_kill, int forcekill, int trapno,
-			  int fail, struct page *page, unsigned long pfn,
+			  bool fail, struct page *page, unsigned long pfn,
 			  int flags)
 {
 	struct to_kill *tk, *next;
@@ -904,13 +904,13 @@ EXPORT_SYMBOL_GPL(get_hwpoison_page);
  * Do all that is necessary to remove user space mappings. Unmap
  * the pages and send SIGBUS to the processes if the data was dirty.
  */
-static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
+static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 				  int trapno, int flags, struct page **hpagep)
 {
 	enum ttu_flags ttu = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
 	struct address_space *mapping;
 	LIST_HEAD(tokill);
-	int ret;
+	bool unmap_success;
 	int kill = 1, forcekill;
 	struct page *hpage = *hpagep;
 
@@ -919,20 +919,20 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * other types of pages.
 	 */
 	if (PageReserved(p) || PageSlab(p))
-		return SWAP_SUCCESS;
+		return true;
 	if (!(PageLRU(hpage) || PageHuge(p)))
-		return SWAP_SUCCESS;
+		return true;
 
 	/*
 	 * This check implies we don't kill processes if their pages
 	 * are in the swap cache early. Those are always late kills.
 	 */
 	if (!page_mapped(hpage))
-		return SWAP_SUCCESS;
+		return true;
 
 	if (PageKsm(p)) {
 		pr_err("Memory failure: %#lx: can't handle KSM pages.\n", pfn);
-		return SWAP_FAIL;
+		return false;
 	}
 
 	if (PageSwapCache(p)) {
@@ -971,8 +971,8 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	if (kill)
 		collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
 
-	ret = try_to_unmap(hpage, ttu);
-	if (ret != SWAP_SUCCESS)
+	unmap_success = try_to_unmap(hpage, ttu);
+	if (!unmap_success)
 		pr_err("Memory failure: %#lx: failed to unmap page (mapcount=%d)\n",
 		       pfn, page_mapcount(hpage));
 
@@ -987,10 +987,9 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 	 * any accesses to the poisoned memory.
 	 */
 	forcekill = PageDirty(hpage) || (flags & MF_MUST_KILL);
-	kill_procs(&tokill, forcekill, trapno,
-		      ret != SWAP_SUCCESS, p, pfn, flags);
+	kill_procs(&tokill, forcekill, trapno, !unmap_success, p, pfn, flags);
 
-	return ret;
+	return unmap_success;
 }
 
 static void set_page_hwpoison_huge_page(struct page *hpage)
@@ -1230,8 +1229,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 	 * When the raw error page is thp tail page, hpage points to the raw
 	 * page after thp split.
 	 */
-	if (hwpoison_user_mappings(p, pfn, trapno, flags, &hpage)
-	    != SWAP_SUCCESS) {
+	if (!hwpoison_user_mappings(p, pfn, trapno, flags, &hpage)) {
 		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
 		res = -EBUSY;
 		goto out;
diff --git a/mm/rmap.c b/mm/rmap.c
index 2a5d854..50c2851 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1496,12 +1496,10 @@ static int page_mapcount_is_zero(struct page *page)
  *
  * Tries to remove all the page table entries which are mapping this
  * page, used in the pageout path.  Caller must hold the page lock.
- * Return values are:
  *
- * SWAP_SUCCESS	- we succeeded in removing all mappings
- * SWAP_FAIL	- the page is unswappable
+ * If unmap is successful, return true. Otherwise, false.
  */
-int try_to_unmap(struct page *page, enum ttu_flags flags)
+bool try_to_unmap(struct page *page, enum ttu_flags flags)
 {
 	struct rmap_walk_control rwc = {
 		.rmap_one = try_to_unmap_one,
@@ -1526,7 +1524,7 @@ int try_to_unmap(struct page *page, enum ttu_flags flags)
 	else
 		rmap_walk(page, &rwc);
 
-	return !page_mapcount(page) ? SWAP_SUCCESS : SWAP_FAIL;
+	return !page_mapcount(page) ? true : false;
 }
 
 static int page_not_mapped(struct page *page)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7727fbe..beffe79 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -967,7 +967,6 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		int may_enter_fs;
 		enum page_references references = PAGEREF_RECLAIM_CLEAN;
 		bool dirty, writeback;
-		int ret = SWAP_SUCCESS;
 
 		cond_resched();
 
@@ -1140,13 +1139,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
 		 * processes. Try to unmap it here.
 		 */
 		if (page_mapped(page)) {
-			switch (ret = try_to_unmap(page,
-				ttu_flags | TTU_BATCH_FLUSH)) {
-			case SWAP_FAIL:
+			if (!try_to_unmap(page, ttu_flags | TTU_BATCH_FLUSH)) {
 				nr_unmap_fail++;
 				goto activate_locked;
-			case SWAP_SUCCESS:
-				; /* try to free the page below */
 			}
 		}
 
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 08/10] mm: make rmap_walk void function

[Minchan Kim]

There is no user of return value from rmap_walk friend so this
patch makes them void function.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/ksm.h  |  5 ++---
 include/linux/rmap.h |  4 ++--
 mm/ksm.c             | 16 ++++++----------
 mm/rmap.c            | 32 +++++++++++++-------------------
 4 files changed, 23 insertions(+), 34 deletions(-)

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index e1cfda4..78b44a0 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -61,7 +61,7 @@ static inline void set_page_stable_node(struct page *page,
 struct page *ksm_might_need_to_copy(struct page *page,
 			struct vm_area_struct *vma, unsigned long address);
 
-int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
 void ksm_migrate_page(struct page *newpage, struct page *oldpage);
 
 #else  /* !CONFIG_KSM */
@@ -94,10 +94,9 @@ static inline int page_referenced_ksm(struct page *page,
 	return 0;
 }
 
-static inline int rmap_walk_ksm(struct page *page,
+static inline void rmap_walk_ksm(struct page *page,
 			struct rmap_walk_control *rwc)
 {
-	return 0;
 }
 
 static inline void ksm_migrate_page(struct page *newpage, struct page *oldpage)
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6028c38..1d7d457c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -264,8 +264,8 @@ struct rmap_walk_control {
 	bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
 };
 
-int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
-int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
+void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
 
 #else	/* !CONFIG_MMU */
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 19b4f2d..6edffb9 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1933,11 +1933,10 @@ struct page *ksm_might_need_to_copy(struct page *page,
 	return new_page;
 }
 
-int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
+void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 {
 	struct stable_node *stable_node;
 	struct rmap_item *rmap_item;
-	int ret = SWAP_AGAIN;
 	int search_new_forks = 0;
 
 	VM_BUG_ON_PAGE(!PageKsm(page), page);
@@ -1950,7 +1949,7 @@ int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 
 	stable_node = page_stable_node(page);
 	if (!stable_node)
-		return ret;
+		return;
 again:
 	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {
 		struct anon_vma *anon_vma = rmap_item->anon_vma;
@@ -1978,23 +1977,20 @@ int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 			if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 				continue;
 
-			ret = rwc->rmap_one(page, vma,
-					rmap_item->address, rwc->arg);
-			if (ret != SWAP_AGAIN) {
+			if (SWAP_AGAIN != rwc->rmap_one(page, vma,
+					rmap_item->address, rwc->arg)) {
 				anon_vma_unlock_read(anon_vma);
-				goto out;
+				return;
 			}
 			if (rwc->done && rwc->done(page)) {
 				anon_vma_unlock_read(anon_vma);
-				goto out;
+				return;
 			}
 		}
 		anon_vma_unlock_read(anon_vma);
 	}
 	if (!search_new_forks++)
 		goto again;
-out:
-	return ret;
 }
 
 #ifdef CONFIG_MIGRATION
diff --git a/mm/rmap.c b/mm/rmap.c
index 50c2851..fbffc5a 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1603,13 +1603,12 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page,
  * vm_flags for that VMA.  That should be OK, because that vma shouldn't be
  * LOCKED.
  */
-static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
+static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
 		bool locked)
 {
 	struct anon_vma *anon_vma;
 	pgoff_t pgoff_start, pgoff_end;
 	struct anon_vma_chain *avc;
-	int ret = SWAP_AGAIN;
 
 	if (locked) {
 		anon_vma = page_anon_vma(page);
@@ -1619,7 +1618,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
 		anon_vma = rmap_walk_anon_lock(page, rwc);
 	}
 	if (!anon_vma)
-		return ret;
+		return;
 
 	pgoff_start = page_to_pgoff(page);
 	pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
@@ -1633,8 +1632,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
 		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 			continue;
 
-		ret = rwc->rmap_one(page, vma, address, rwc->arg);
-		if (ret != SWAP_AGAIN)
+		if (SWAP_AGAIN != rwc->rmap_one(page, vma, address, rwc->arg))
 			break;
 		if (rwc->done && rwc->done(page))
 			break;
@@ -1642,7 +1640,6 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
 
 	if (!locked)
 		anon_vma_unlock_read(anon_vma);
-	return ret;
 }
 
 /*
@@ -1658,13 +1655,12 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
  * vm_flags for that VMA.  That should be OK, because that vma shouldn't be
  * LOCKED.
  */
-static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
+static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
 		bool locked)
 {
 	struct address_space *mapping = page_mapping(page);
 	pgoff_t pgoff_start, pgoff_end;
 	struct vm_area_struct *vma;
-	int ret = SWAP_AGAIN;
 
 	/*
 	 * The page lock not only makes sure that page->mapping cannot
@@ -1675,7 +1671,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
 
 	if (!mapping)
-		return ret;
+		return;
 
 	pgoff_start = page_to_pgoff(page);
 	pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
@@ -1690,8 +1686,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
 		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 			continue;
 
-		ret = rwc->rmap_one(page, vma, address, rwc->arg);
-		if (ret != SWAP_AGAIN)
+		if (SWAP_AGAIN != rwc->rmap_one(page, vma, address, rwc->arg))
 			goto done;
 		if (rwc->done && rwc->done(page))
 			goto done;
@@ -1700,28 +1695,27 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
 done:
 	if (!locked)
 		i_mmap_unlock_read(mapping);
-	return ret;
 }
 
-int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
+void rmap_walk(struct page *page, struct rmap_walk_control *rwc)
 {
 	if (unlikely(PageKsm(page)))
-		return rmap_walk_ksm(page, rwc);
+		rmap_walk_ksm(page, rwc);
 	else if (PageAnon(page))
-		return rmap_walk_anon(page, rwc, false);
+		rmap_walk_anon(page, rwc, false);
 	else
-		return rmap_walk_file(page, rwc, false);
+		rmap_walk_file(page, rwc, false);
 }
 
 /* Like rmap_walk, but caller holds relevant rmap lock */
-int rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
+void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
 {
 	/* no ksm support for now */
 	VM_BUG_ON_PAGE(PageKsm(page), page);
 	if (PageAnon(page))
-		return rmap_walk_anon(page, rwc, true);
+		rmap_walk_anon(page, rwc, true);
 	else
-		return rmap_walk_file(page, rwc, true);
+		rmap_walk_file(page, rwc, true);
 }
 
 #ifdef CONFIG_HUGETLB_PAGE
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 09/10] mm: make rmap_one boolean function

[Minchan Kim]

rmap_one's return value controls whether rmap_work should contine to
scan other ptes or not so it's target for changing to boolean.
Return true if the scan should be continued. Otherwise, return false
to stop the scanning.

This patch makes rmap_one's return value to boolean.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h |  2 +-
 mm/ksm.c             |  2 +-
 mm/migrate.c         |  4 ++--
 mm/page_idle.c       |  4 ++--
 mm/rmap.c            | 30 +++++++++++++++---------------
 5 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 1d7d457c..59d7dd7 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -257,7 +257,7 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
  */
 struct rmap_walk_control {
 	void *arg;
-	int (*rmap_one)(struct page *page, struct vm_area_struct *vma,
+	bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
 					unsigned long addr, void *arg);
 	int (*done)(struct page *page);
 	struct anon_vma *(*anon_lock)(struct page *page);
diff --git a/mm/ksm.c b/mm/ksm.c
index 6edffb9..d9fc0e4 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1977,7 +1977,7 @@ void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 			if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 				continue;
 
-			if (SWAP_AGAIN != rwc->rmap_one(page, vma,
+			if (!rwc->rmap_one(page, vma,
 					rmap_item->address, rwc->arg)) {
 				anon_vma_unlock_read(anon_vma);
 				return;
diff --git a/mm/migrate.c b/mm/migrate.c
index e0cb4b7..8e9f1e8 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -194,7 +194,7 @@ void putback_movable_pages(struct list_head *l)
 /*
  * Restore a potential migration pte to a working pte entry
  */
-static int remove_migration_pte(struct page *page, struct vm_area_struct *vma,
+static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
 				 unsigned long addr, void *old)
 {
 	struct page_vma_mapped_walk pvmw = {
@@ -250,7 +250,7 @@ static int remove_migration_pte(struct page *page, struct vm_area_struct *vma,
 		update_mmu_cache(vma, pvmw.address, pvmw.pte);
 	}
 
-	return SWAP_AGAIN;
+	return true;
 }
 
 /*
diff --git a/mm/page_idle.c b/mm/page_idle.c
index b0ee56c..1b0f48c 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -50,7 +50,7 @@ static struct page *page_idle_get_page(unsigned long pfn)
 	return page;
 }
 
-static int page_idle_clear_pte_refs_one(struct page *page,
+static bool page_idle_clear_pte_refs_one(struct page *page,
 					struct vm_area_struct *vma,
 					unsigned long addr, void *arg)
 {
@@ -84,7 +84,7 @@ static int page_idle_clear_pte_refs_one(struct page *page,
 		 */
 		set_page_young(page);
 	}
-	return SWAP_AGAIN;
+	return true;
 }
 
 static void page_idle_clear_pte_refs(struct page *page)
diff --git a/mm/rmap.c b/mm/rmap.c
index fbffc5a..2422758 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -719,7 +719,7 @@ struct page_referenced_arg {
 /*
  * arg: page_referenced_arg will be passed
  */
-static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
+static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
 			unsigned long address, void *arg)
 {
 	struct page_referenced_arg *pra = arg;
@@ -736,7 +736,7 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
 		if (vma->vm_flags & VM_LOCKED) {
 			page_vma_mapped_walk_done(&pvmw);
 			pra->vm_flags |= VM_LOCKED;
-			return SWAP_FAIL; /* To break the loop */
+			return false; /* To break the loop */
 		}
 
 		if (pvmw.pte) {
@@ -776,9 +776,9 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
 	}
 
 	if (!pra->mapcount)
-		return SWAP_SUCCESS; /* To break the loop */
+		return false; /* To break the loop */
 
-	return SWAP_AGAIN;
+	return true;
 }
 
 static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
@@ -849,7 +849,7 @@ int page_referenced(struct page *page,
 	return pra.referenced;
 }
 
-static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
+static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 			    unsigned long address, void *arg)
 {
 	struct page_vma_mapped_walk pvmw = {
@@ -902,7 +902,7 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
 		}
 	}
 
-	return SWAP_AGAIN;
+	return true;
 }
 
 static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
@@ -1285,7 +1285,7 @@ void page_remove_rmap(struct page *page, bool compound)
 /*
  * @arg: enum ttu_flags will be passed to this argument
  */
-static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
+static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		     unsigned long address, void *arg)
 {
 	struct mm_struct *mm = vma->vm_mm;
@@ -1296,12 +1296,12 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	};
 	pte_t pteval;
 	struct page *subpage;
-	int ret = SWAP_AGAIN;
+	bool ret = true;
 	enum ttu_flags flags = (enum ttu_flags)arg;
 
 	/* munlock has nothing to gain from examining un-locked vmas */
 	if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
-		return SWAP_AGAIN;
+		return true;
 
 	if (flags & TTU_SPLIT_HUGE_PMD) {
 		split_huge_pmd_address(vma, address,
@@ -1324,7 +1324,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 					 */
 					mlock_vma_page(page);
 				}
-				ret = SWAP_FAIL;
+				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1342,7 +1342,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		if (!(flags & TTU_IGNORE_ACCESS)) {
 			if (ptep_clear_flush_young_notify(vma, address,
 						pvmw.pte)) {
-				ret = SWAP_FAIL;
+				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1432,14 +1432,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 				 */
 				set_pte_at(mm, address, pvmw.pte, pteval);
 				SetPageSwapBacked(page);
-				ret = SWAP_FAIL;
+				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
 
 			if (swap_duplicate(entry) < 0) {
 				set_pte_at(mm, address, pvmw.pte, pteval);
-				ret = SWAP_FAIL;
+				ret = false;
 				page_vma_mapped_walk_done(&pvmw);
 				break;
 			}
@@ -1632,7 +1632,7 @@ static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
 		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 			continue;
 
-		if (SWAP_AGAIN != rwc->rmap_one(page, vma, address, rwc->arg))
+		if (!rwc->rmap_one(page, vma, address, rwc->arg))
 			break;
 		if (rwc->done && rwc->done(page))
 			break;
@@ -1686,7 +1686,7 @@ static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
 		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
 			continue;
 
-		if (SWAP_AGAIN != rwc->rmap_one(page, vma, address, rwc->arg))
+		if (!rwc->rmap_one(page, vma, address, rwc->arg))
 			goto done;
 		if (rwc->done && rwc->done(page))
 			goto done;
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v1 09/10] mm: make rmap_one boolean function

[Andrew Morton]

On Mon, 13 Mar 2017 09:35:52 +0900 Minchan Kim <minchan@kernel.org> wrote:

> rmap_one's return value controls whether rmap_work should contine to
> scan other ptes or not so it's target for changing to boolean.
> Return true if the scan should be continued. Otherwise, return false
> to stop the scanning.
> 
> This patch makes rmap_one's return value to boolean.

"SWAP_AGAIN" conveys meaning to the reader, whereas the meaning of
"true" is unclear.  So it would be better to document the return value
of these functions.


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v1 09/10] mm: make rmap_one boolean function

[Minchan Kim]

Hi Andrew,

On Mon, Mar 13, 2017 at 12:45:00PM -0700, Andrew Morton wrote:
> On Mon, 13 Mar 2017 09:35:52 +0900 Minchan Kim <minchan@kernel.org> wrote:
> 
> > rmap_one's return value controls whether rmap_work should contine to
> > scan other ptes or not so it's target for changing to boolean.
> > Return true if the scan should be continued. Otherwise, return false
> > to stop the scanning.
> > 
> > This patch makes rmap_one's return value to boolean.
> 
> "SWAP_AGAIN" conveys meaning to the reader, whereas the meaning of
> "true" is unclear.  So it would be better to document the return value
> of these functions.

Fair enough.
I will add description like this.

        /*
         * Return false if page table scanning in rmap_walk should be stopped.
         * Otherwise, return true.
         */
        bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
                                        unsigned long addr, void *arg);


I will wait by noon tomorrow and if there are no further comment,
I will resend v2.

Thanks.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v1 10/10] mm: remove SWAP_[SUCCESS|AGAIN|FAIL]

[Minchan Kim]

There is no user for it. Remove it.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/rmap.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 59d7dd7..5d6788f 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -291,11 +291,4 @@ static inline int page_mkclean(struct page *page)
 
 #endif	/* CONFIG_MMU */
 
-/*
- * Return values of try_to_unmap
- */
-#define SWAP_SUCCESS	0
-#define SWAP_AGAIN	1
-#define SWAP_FAIL	2
-
 #endif	/* _LINUX_RMAP_H */
-- 
2.7.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>