Re: [PATCH v2 03/23] powerpc/pseries/cmm: remove cmm_balloon_compaction_init()

[David Hildenbrand (Red Hat)]

@@ -573,11 +567,12 @@ static int cmm_init(void)
return -EOPNOTSUPP;

balloon_devinfo_init(&b_dev_info);
-   cmm_balloon_compaction_init();
+   if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
+   b_dev_info.migratepage = cmm_migratepage;

rc = register_oom_notifier(&cmm_oom_nb);
if (rc < 0)
-   goto out_balloon_compaction;
+   return rc;

if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
goto out_oom_notifier;
@@ -606,7 +601,6 @@ static int cmm_init(void)
unregister_reboot_notifier(&cmm_reboot_nb);
  out_oom_notifier:
unregister_oom_notifier(&cmm_oom_nb);
-out_balloon_compaction:


So silly, I assume before there was more that happened here?


Right, I commented that above in the patch description.

Thanks!

--
Cheers

David

Re: [PATCH v2 03/23] powerpc/pseries/cmm: remove cmm_balloon_compaction_init()

[Lorenzo Stoakes]

On Thu, Jan 15, 2026 at 10:19:53AM +0100, David Hildenbrand (Red Hat) wrote:
> Now that there is not a lot of logic left, let's just inline setting up
> the migration function.
>
> To avoid #ifdef in the caller we can instead use IS_ENABLED() and make
> the compiler happy by only providing the function declaration.
>
> Now that the function is gone, drop the "out_balloon_compaction" label.
> Note that before commit 68f2736a8583 ("mm: Convert all PageMovable users
> to movable_operations") we actually had to undo something, now not anymore.
>
> Signed-off-by: David Hildenbrand (Red Hat) 

Seems reasonable so:

Reviewed-by: Lorenzo Stoakes 

> ---
>  arch/powerpc/platforms/pseries/cmm.c | 16 +---
>  1 file changed, 5 insertions(+), 11 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/cmm.c 
> b/arch/powerpc/platforms/pseries/cmm.c
> index 4cbbe2ee58aba..9a6efbc80d2ad 100644
> --- a/arch/powerpc/platforms/pseries/cmm.c
> +++ b/arch/powerpc/platforms/pseries/cmm.c
> @@ -548,15 +548,9 @@ static int cmm_migratepage(struct balloon_dev_info 
> *b_dev_info,
>
>   return 0;
>  }
> -
> -static void cmm_balloon_compaction_init(void)
> -{
> - b_dev_info.migratepage = cmm_migratepage;
> -}
>  #else /* CONFIG_BALLOON_COMPACTION */
> -static void cmm_balloon_compaction_init(void)
> -{
> -}
> +int cmm_migratepage(struct balloon_dev_info *b_dev_info, struct page 
> *newpage,
> + struct page *page, enum migrate_mode mode);
>  #endif /* CONFIG_BALLOON_COMPACTION */
>
>  /**
> @@ -573,11 +567,12 @@ static int cmm_init(void)
>   return -EOPNOTSUPP;
>
>   balloon_devinfo_init(&b_dev_info);
> - cmm_balloon_compaction_init();
> + if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
> + b_dev_info.migratepage = cmm_migratepage;
>
>   rc = register_oom_notifier(&cmm_oom_nb);
>   if (rc < 0)
> - goto out_balloon_compaction;
> + return rc;
>
>   if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
>   goto out_oom_notifier;
> @@ -606,7 +601,6 @@ static int cmm_init(void)
>   unregister_reboot_notifier(&cmm_reboot_nb);
>  out_oom_notifier:
>   unregister_oom_notifier(&cmm_oom_nb);
> -out_balloon_compaction:

So silly, I assume before there was more that happened here?

>   return rc;
>  }
>
> --
> 2.52.0
>

[PATCH v2 03/23] powerpc/pseries/cmm: remove cmm_balloon_compaction_init()

[David Hildenbrand (Red Hat)]

Now that there is not a lot of logic left, let's just inline setting up
the migration function.

To avoid #ifdef in the caller we can instead use IS_ENABLED() and make
the compiler happy by only providing the function declaration.

Now that the function is gone, drop the "out_balloon_compaction" label.
Note that before commit 68f2736a8583 ("mm: Convert all PageMovable users
to movable_operations") we actually had to undo something, now not anymore.

Signed-off-by: David Hildenbrand (Red Hat) 
---
 arch/powerpc/platforms/pseries/cmm.c | 16 +---
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/cmm.c 
b/arch/powerpc/platforms/pseries/cmm.c
index 4cbbe2ee58aba..9a6efbc80d2ad 100644
--- a/arch/powerpc/platforms/pseries/cmm.c
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -548,15 +548,9 @@ static int cmm_migratepage(struct balloon_dev_info 
*b_dev_info,
 
return 0;
 }
-
-static void cmm_balloon_compaction_init(void)
-{
-   b_dev_info.migratepage = cmm_migratepage;
-}
 #else /* CONFIG_BALLOON_COMPACTION */
-static void cmm_balloon_compaction_init(void)
-{
-}
+int cmm_migratepage(struct balloon_dev_info *b_dev_info, struct page *newpage,
+   struct page *page, enum migrate_mode mode);
 #endif /* CONFIG_BALLOON_COMPACTION */
 
 /**
@@ -573,11 +567,12 @@ static int cmm_init(void)
return -EOPNOTSUPP;
 
balloon_devinfo_init(&b_dev_info);
-   cmm_balloon_compaction_init();
+   if (IS_ENABLED(CONFIG_BALLOON_COMPACTION))
+   b_dev_info.migratepage = cmm_migratepage;
 
rc = register_oom_notifier(&cmm_oom_nb);
if (rc < 0)
-   goto out_balloon_compaction;
+   return rc;
 
if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
goto out_oom_notifier;
@@ -606,7 +601,6 @@ static int cmm_init(void)
unregister_reboot_notifier(&cmm_reboot_nb);
 out_oom_notifier:
unregister_oom_notifier(&cmm_oom_nb);
-out_balloon_compaction:
return rc;
 }
 
-- 
2.52.0