Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Joonsoo Kim 
On Mon, Dec 02, 2013 at 02:51:05PM -0800, Andrew Morton wrote:
> On Mon, 02 Dec 2013 15:09:33 -0500 Naoya Horiguchi 
>  wrote:
> 
> > > --- a/include/linux/rmap.h
> > > +++ b/include/linux/rmap.h
> > > @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct 
> > > page *page);
> > >  void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
> > >  int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
> > >  
> > > +struct rmap_walk_control {
> > > + int (*main)(struct page *, struct vm_area_struct *,
> > > + unsigned long, void *);
> > 
> > Maybe you can add parameters' names to make this prototype more readable.
> > 
> 
> Yes, I find it quite maddening when the names are left out.  They're really
> very useful for understanding what's going on.

Okay. Will do.

> 
> The name "main" seems odd as well.  What does "main" mean?  "rmap_one"
> was better, but "rmap_one_page" or "rmap_one_pte" or whatever would
> be better.

Okay. I will think better name.

Thanks.
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Andrew Morton 
On Thu, 28 Nov 2013 16:48:41 +0900 Joonsoo Kim  wrote:

> In each rmap traverse case, there is some difference so that we need
> function pointers and arguments to them in order to handle these
> difference properly.
> 
> For this purpose, struct rmap_walk_control is introduced in this patch,
> and will be extended in following patch. Introducing and extending are
> separate, because it clarify changes.
> 
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -198,7 +198,12 @@ out:
>   */
>  static void remove_migration_ptes(struct page *old, struct page *new)
>  {
> - rmap_walk(new, remove_migration_pte, old);
> + struct rmap_walk_control rwc;
> +
> + memset(, 0, sizeof(rwc));
> + rwc.main = remove_migration_pte;
> + rwc.arg = old;
> + rmap_walk(new, );
>  }

It is much neater to do

struct rmap_walk_control rwc = {
.main = remove_migration_pte,
.arg = old,
};

which will zero out all remaining fields as well.
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Andrew Morton 
On Mon, 02 Dec 2013 15:09:33 -0500 Naoya Horiguchi  
wrote:

> > --- a/include/linux/rmap.h
> > +++ b/include/linux/rmap.h
> > @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
> > *page);
> >  void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
> >  int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
> >  
> > +struct rmap_walk_control {
> > +   int (*main)(struct page *, struct vm_area_struct *,
> > +   unsigned long, void *);
> 
> Maybe you can add parameters' names to make this prototype more readable.
> 

Yes, I find it quite maddening when the names are left out.  They're really
very useful for understanding what's going on.

The name "main" seems odd as well.  What does "main" mean?  "rmap_one"
was better, but "rmap_one_page" or "rmap_one_pte" or whatever would
be better.
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Naoya Horiguchi 
On Thu, Nov 28, 2013 at 04:48:41PM +0900, Joonsoo Kim wrote:
> In each rmap traverse case, there is some difference so that we need
> function pointers and arguments to them in order to handle these
> difference properly.
> 
> For this purpose, struct rmap_walk_control is introduced in this patch,
> and will be extended in following patch. Introducing and extending are
> separate, because it clarify changes.
> 
> Signed-off-by: Joonsoo Kim 

Reviewed-by: Naoya Horiguchi 

A few comment below ...

> diff --git a/include/linux/ksm.h b/include/linux/ksm.h
> index 45c9b6a..0eef8cb 100644
> --- a/include/linux/ksm.h
> +++ b/include/linux/ksm.h
> @@ -76,8 +76,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
>  int page_referenced_ksm(struct page *page,
>   struct mem_cgroup *memcg, unsigned long *vm_flags);
>  int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
> -int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
> -   struct vm_area_struct *, unsigned long, void *), void *arg);
> +int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
>  void ksm_migrate_page(struct page *newpage, struct page *oldpage);
>  
>  #else  /* !CONFIG_KSM */
> @@ -120,8 +119,8 @@ static inline int try_to_unmap_ksm(struct page *page, 
> enum ttu_flags flags)
>   return 0;
>  }
>  
> -static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct 
> page*,
> - struct vm_area_struct *, unsigned long, void *), void *arg)
> +static inline int rmap_walk_ksm(struct page *page,
> + struct rmap_walk_control *rwc)
>  {
>   return 0;
>  }
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index 6dacb93..0f65686 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
> *page);
>  void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
>  int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
>  
> +struct rmap_walk_control {
> + int (*main)(struct page *, struct vm_area_struct *,
> + unsigned long, void *);

Maybe you can add parameters' names to make this prototype more readable.

> + void *arg;  /* argument to main function */
> +};
> +
>  /*
>   * Called by migrate.c to remove migration ptes, but might be used more 
> later.
>   */

This comment also needs update?

Thanks,
Naoya Horiguchi
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Naoya Horiguchi 
On Thu, Nov 28, 2013 at 04:48:41PM +0900, Joonsoo Kim wrote:
 In each rmap traverse case, there is some difference so that we need
 function pointers and arguments to them in order to handle these
 difference properly.
 
 For this purpose, struct rmap_walk_control is introduced in this patch,
 and will be extended in following patch. Introducing and extending are
 separate, because it clarify changes.
 
 Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com

Reviewed-by: Naoya Horiguchi n-horigu...@ah.jp.nec.com

A few comment below ...

 diff --git a/include/linux/ksm.h b/include/linux/ksm.h
 index 45c9b6a..0eef8cb 100644
 --- a/include/linux/ksm.h
 +++ b/include/linux/ksm.h
 @@ -76,8 +76,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
  int page_referenced_ksm(struct page *page,
   struct mem_cgroup *memcg, unsigned long *vm_flags);
  int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
 -int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
 -   struct vm_area_struct *, unsigned long, void *), void *arg);
 +int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
  void ksm_migrate_page(struct page *newpage, struct page *oldpage);
  
  #else  /* !CONFIG_KSM */
 @@ -120,8 +119,8 @@ static inline int try_to_unmap_ksm(struct page *page, 
 enum ttu_flags flags)
   return 0;
  }
  
 -static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct 
 page*,
 - struct vm_area_struct *, unsigned long, void *), void *arg)
 +static inline int rmap_walk_ksm(struct page *page,
 + struct rmap_walk_control *rwc)
  {
   return 0;
  }
 diff --git a/include/linux/rmap.h b/include/linux/rmap.h
 index 6dacb93..0f65686 100644
 --- a/include/linux/rmap.h
 +++ b/include/linux/rmap.h
 @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
 *page);
  void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
  int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
  
 +struct rmap_walk_control {
 + int (*main)(struct page *, struct vm_area_struct *,
 + unsigned long, void *);

Maybe you can add parameters' names to make this prototype more readable.

 + void *arg;  /* argument to main function */
 +};
 +
  /*
   * Called by migrate.c to remove migration ptes, but might be used more 
 later.
   */

This comment also needs update?

Thanks,
Naoya Horiguchi
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Andrew Morton 
On Mon, 02 Dec 2013 15:09:33 -0500 Naoya Horiguchi n-horigu...@ah.jp.nec.com 
wrote:

  --- a/include/linux/rmap.h
  +++ b/include/linux/rmap.h
  @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
  *page);
   void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
   int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
   
  +struct rmap_walk_control {
  +   int (*main)(struct page *, struct vm_area_struct *,
  +   unsigned long, void *);
 
 Maybe you can add parameters' names to make this prototype more readable.
 

Yes, I find it quite maddening when the names are left out.  They're really
very useful for understanding what's going on.

The name main seems odd as well.  What does main mean?  rmap_one
was better, but rmap_one_page or rmap_one_pte or whatever would
be better.
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Andrew Morton 
On Thu, 28 Nov 2013 16:48:41 +0900 Joonsoo Kim iamjoonsoo@lge.com wrote:

 In each rmap traverse case, there is some difference so that we need
 function pointers and arguments to them in order to handle these
 difference properly.
 
 For this purpose, struct rmap_walk_control is introduced in this patch,
 and will be extended in following patch. Introducing and extending are
 separate, because it clarify changes.
 
 --- a/mm/migrate.c
 +++ b/mm/migrate.c
 @@ -198,7 +198,12 @@ out:
   */
  static void remove_migration_ptes(struct page *old, struct page *new)
  {
 - rmap_walk(new, remove_migration_pte, old);
 + struct rmap_walk_control rwc;
 +
 + memset(rwc, 0, sizeof(rwc));
 + rwc.main = remove_migration_pte;
 + rwc.arg = old;
 + rmap_walk(new, rwc);
  }

It is much neater to do

struct rmap_walk_control rwc = {
.main = remove_migration_pte,
.arg = old,
};

which will zero out all remaining fields as well.
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Re: [PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-12-02 Thread Joonsoo Kim 
On Mon, Dec 02, 2013 at 02:51:05PM -0800, Andrew Morton wrote:
 On Mon, 02 Dec 2013 15:09:33 -0500 Naoya Horiguchi 
 n-horigu...@ah.jp.nec.com wrote:
 
   --- a/include/linux/rmap.h
   +++ b/include/linux/rmap.h
   @@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct 
   page *page);
void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);

   +struct rmap_walk_control {
   + int (*main)(struct page *, struct vm_area_struct *,
   + unsigned long, void *);
  
  Maybe you can add parameters' names to make this prototype more readable.
  
 
 Yes, I find it quite maddening when the names are left out.  They're really
 very useful for understanding what's going on.

Okay. Will do.

 
 The name main seems odd as well.  What does main mean?  rmap_one
 was better, but rmap_one_page or rmap_one_pte or whatever would
 be better.

Okay. I will think better name.

Thanks.
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[PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-11-27 Thread Joonsoo Kim 
In each rmap traverse case, there is some difference so that we need
function pointers and arguments to them in order to handle these
difference properly.

For this purpose, struct rmap_walk_control is introduced in this patch,
and will be extended in following patch. Introducing and extending are
separate, because it clarify changes.

Signed-off-by: Joonsoo Kim 

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 45c9b6a..0eef8cb 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -76,8 +76,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
 int page_referenced_ksm(struct page *page,
struct mem_cgroup *memcg, unsigned long *vm_flags);
 int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
-int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
- struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
 void ksm_migrate_page(struct page *newpage, struct page *oldpage);
 
 #else  /* !CONFIG_KSM */
@@ -120,8 +119,8 @@ static inline int try_to_unmap_ksm(struct page *page, enum 
ttu_flags flags)
return 0;
 }
 
-static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct 
page*,
-   struct vm_area_struct *, unsigned long, void *), void *arg)
+static inline int rmap_walk_ksm(struct page *page,
+   struct rmap_walk_control *rwc)
 {
return 0;
 }
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6dacb93..0f65686 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
*page);
 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 
+struct rmap_walk_control {
+   int (*main)(struct page *, struct vm_area_struct *,
+   unsigned long, void *);
+   void *arg;  /* argument to main function */
+};
+
 /*
  * Called by migrate.c to remove migration ptes, but might be used more later.
  */
-int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
-   struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
 
 #else  /* !CONFIG_MMU */
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 175fff7..c42ec30 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1997,8 +1997,7 @@ out:
 }
 
 #ifdef CONFIG_MIGRATION
-int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
- struct vm_area_struct *, unsigned long, void *), void *arg)
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 {
struct stable_node *stable_node;
struct rmap_item *rmap_item;
@@ -2033,7 +2032,8 @@ again:
if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
continue;
 
-   ret = rmap_one(page, vma, rmap_item->address, arg);
+   ret = rwc->main(page, vma,
+   rmap_item->address, rwc->arg);
if (ret != SWAP_AGAIN) {
anon_vma_unlock_read(anon_vma);
goto out;
diff --git a/mm/migrate.c b/mm/migrate.c
index bb94004..c47425b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -198,7 +198,12 @@ out:
  */
 static void remove_migration_ptes(struct page *old, struct page *new)
 {
-   rmap_walk(new, remove_migration_pte, old);
+   struct rmap_walk_control rwc;
+
+   memset(, 0, sizeof(rwc));
+   rwc.main = remove_migration_pte;
+   rwc.arg = old;
+   rmap_walk(new, );
 }
 
 /*
diff --git a/mm/rmap.c b/mm/rmap.c
index 916f2ed..5933488 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1705,8 +1705,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page 
*page)
  * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
  * Called by migrate.c to remove migration ptes, but might be used more later.
  */
-static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
-   struct vm_area_struct *, unsigned long, void *), void *arg)
+static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
 {
struct anon_vma *anon_vma;
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
@@ -1720,7 +1719,7 @@ static int rmap_walk_anon(struct page *page, int 
(*rmap_one)(struct page *,
anon_vma_interval_tree_foreach(avc, _vma->rb_root, pgoff, pgoff) {
struct vm_area_struct *vma = avc->vma;
unsigned long address = vma_address(page, vma);
-   ret = rmap_one(page, vma, address, arg);
+   ret = rwc->main(page, vma, address, rwc->arg);
if (ret != SWAP_AGAIN)
break;
}
@@ -1728,8 +1727,7 @@ static int

[PATCH 4/9] mm/rmap: make rmap_walk to get the rmap_walk_control argument

2013-11-27 Thread Joonsoo Kim 
In each rmap traverse case, there is some difference so that we need
function pointers and arguments to them in order to handle these
difference properly.

For this purpose, struct rmap_walk_control is introduced in this patch,
and will be extended in following patch. Introducing and extending are
separate, because it clarify changes.

Signed-off-by: Joonsoo Kim iamjoonsoo@lge.com

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 45c9b6a..0eef8cb 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -76,8 +76,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
 int page_referenced_ksm(struct page *page,
struct mem_cgroup *memcg, unsigned long *vm_flags);
 int try_to_unmap_ksm(struct page *page, enum ttu_flags flags);
-int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
- struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc);
 void ksm_migrate_page(struct page *newpage, struct page *oldpage);
 
 #else  /* !CONFIG_KSM */
@@ -120,8 +119,8 @@ static inline int try_to_unmap_ksm(struct page *page, enum 
ttu_flags flags)
return 0;
 }
 
-static inline int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct 
page*,
-   struct vm_area_struct *, unsigned long, void *), void *arg)
+static inline int rmap_walk_ksm(struct page *page,
+   struct rmap_walk_control *rwc)
 {
return 0;
 }
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6dacb93..0f65686 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -235,11 +235,16 @@ struct anon_vma *page_lock_anon_vma_read(struct page 
*page);
 void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 
+struct rmap_walk_control {
+   int (*main)(struct page *, struct vm_area_struct *,
+   unsigned long, void *);
+   void *arg;  /* argument to main function */
+};
+
 /*
  * Called by migrate.c to remove migration ptes, but might be used more later.
  */
-int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
-   struct vm_area_struct *, unsigned long, void *), void *arg);
+int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
 
 #else  /* !CONFIG_MMU */
 
diff --git a/mm/ksm.c b/mm/ksm.c
index 175fff7..c42ec30 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1997,8 +1997,7 @@ out:
 }
 
 #ifdef CONFIG_MIGRATION
-int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
- struct vm_area_struct *, unsigned long, void *), void *arg)
+int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
 {
struct stable_node *stable_node;
struct rmap_item *rmap_item;
@@ -2033,7 +2032,8 @@ again:
if ((rmap_item-mm == vma-vm_mm) == search_new_forks)
continue;
 
-   ret = rmap_one(page, vma, rmap_item-address, arg);
+   ret = rwc-main(page, vma,
+   rmap_item-address, rwc-arg);
if (ret != SWAP_AGAIN) {
anon_vma_unlock_read(anon_vma);
goto out;
diff --git a/mm/migrate.c b/mm/migrate.c
index bb94004..c47425b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -198,7 +198,12 @@ out:
  */
 static void remove_migration_ptes(struct page *old, struct page *new)
 {
-   rmap_walk(new, remove_migration_pte, old);
+   struct rmap_walk_control rwc;
+
+   memset(rwc, 0, sizeof(rwc));
+   rwc.main = remove_migration_pte;
+   rwc.arg = old;
+   rmap_walk(new, rwc);
 }
 
 /*
diff --git a/mm/rmap.c b/mm/rmap.c
index 916f2ed..5933488 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1705,8 +1705,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page 
*page)
  * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
  * Called by migrate.c to remove migration ptes, but might be used more later.
  */
-static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
-   struct vm_area_struct *, unsigned long, void *), void *arg)
+static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
 {
struct anon_vma *anon_vma;
pgoff_t pgoff = page-index  (PAGE_CACHE_SHIFT - PAGE_SHIFT);
@@ -1720,7 +1719,7 @@ static int rmap_walk_anon(struct page *page, int 
(*rmap_one)(struct page *,
anon_vma_interval_tree_foreach(avc, anon_vma-rb_root, pgoff, pgoff) {
struct vm_area_struct *vma = avc-vma;
unsigned long address = vma_address(page, vma);
-   ret = rmap_one(page, vma, address, arg);
+   ret = rwc-main(page, vma, address, rwc-arg);
if (ret != SWAP_AGAIN)
break;
}
@@ -1728,8 +1727,7 @@ static int