[PATCH] mm/migration: make isolate_movable_page always defined

[PATCH] mm/migration: make isolate_movable_page always defined

[Yisheng Xie]

Define isolate_movable_page as a static inline function when
CONFIG_MIGRATION is not enable. It should return false
here which means failed to isolate movable pages.

This patch do not have any functional change but to resolve compile
error caused by former commit "HWPOISON: soft offlining for non-lru
movable page" with CONFIG_MIGRATION disabled.

Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
---
 include/linux/migrate.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index ae8d475..631a8c8 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -56,6 +56,8 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
 		free_page_t free, unsigned long private, enum migrate_mode mode,
 		int reason)
 	{ return -ENOSYS; }
+static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
+	{ return false; }
 
 static inline int migrate_prep(void) { return -ENOSYS; }
 static inline int migrate_prep_local(void) { return -ENOSYS; }
-- 
1.7.12.4

Re: [PATCH] mm/migration: make isolate_movable_page always defined

[Yisheng Xie]

Hi Andrew, Minchan, and all:
My former patch "HWPOISON: soft offlining for non-lru
movable page" will cause compiled error when disable
CONFIG_MIGRATION. And this is a patch to fixe it by
define isolate_movable_page as a static inline
function with !CONFIG_MIGRATION.

Could you please help to review it ? Thanks so much~

I am so sorry about that.

Thanks.
Yisheng Xie

On 2017/1/25 18:36, Yisheng Xie wrote:
> Define isolate_movable_page as a static inline function when
> CONFIG_MIGRATION is not enable. It should return false
> here which means failed to isolate movable pages.
> 
> This patch do not have any functional change but to resolve compile
> error caused by former commit "HWPOISON: soft offlining for non-lru
> movable page" with CONFIG_MIGRATION disabled.
> 
> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
> ---
>  include/linux/migrate.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index ae8d475..631a8c8 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -56,6 +56,8 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
>  		free_page_t free, unsigned long private, enum migrate_mode mode,
>  		int reason)
>  	{ return -ENOSYS; }
> +static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
> +	{ return false; }
>  
>  static inline int migrate_prep(void) { return -ENOSYS; }
>  static inline int migrate_prep_local(void) { return -ENOSYS; }
> 

Re: [PATCH] mm/migration: make isolate_movable_page always defined

[Michal Hocko]

On Wed 25-01-17 18:36:03, Yisheng Xie wrote:
> Define isolate_movable_page as a static inline function when
> CONFIG_MIGRATION is not enable. It should return false
> here which means failed to isolate movable pages.
> 
> This patch do not have any functional change but to resolve compile
> error caused by former commit "HWPOISON: soft offlining for non-lru
> movable page" with CONFIG_MIGRATION disabled.
> 
> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
> ---
>  include/linux/migrate.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index ae8d475..631a8c8 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -56,6 +56,8 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
>  		free_page_t free, unsigned long private, enum migrate_mode mode,
>  		int reason)
>  	{ return -ENOSYS; }
> +static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
> +	{ return false; }

OK, so we return false here which will make __soft_offline_page return
true all the way up. Is this really what we want? Don't we want to
return EBUSY in that case? The error code propagation here is just
one big mess.

>  
>  static inline int migrate_prep(void) { return -ENOSYS; }
>  static inline int migrate_prep_local(void) { return -ENOSYS; }
> -- 
> 1.7.12.4
> 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/migration: make isolate_movable_page always defined

[Yisheng Xie]

Hi, Michal,
Thanks for reviewing.
On 01/25/2017 08:01 PM, Michal Hocko wrote:
> On Wed 25-01-17 18:36:03, Yisheng Xie wrote:
>> Define isolate_movable_page as a static inline function when
>> CONFIG_MIGRATION is not enable. It should return false
>> here which means failed to isolate movable pages.
>>
>> This patch do not have any functional change but to resolve compile
>> error caused by former commit "HWPOISON: soft offlining for non-lru
>> movable page" with CONFIG_MIGRATION disabled.
>>
>> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
>> ---
>>  include/linux/migrate.h | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
>> index ae8d475..631a8c8 100644
>> --- a/include/linux/migrate.h
>> +++ b/include/linux/migrate.h
>> @@ -56,6 +56,8 @@ static inline int migrate_pages(struct list_head *l, new_page_t new,
>>  		free_page_t free, unsigned long private, enum migrate_mode mode,
>>  		int reason)
>>  	{ return -ENOSYS; }
>> +static inline bool isolate_movable_page(struct page *page, isolate_mode_t mode)
>> +	{ return false; }
> OK, so we return false here which will make __soft_offline_page return
> true all the way up. Is this really what we want? Don't we want to
> return EBUSY in that case? The error code propagation here is just
> one big mess.
That's right, my stupid coding really make a big mess here.
I will make another version for patch  "HWPOISON:
soft offlining for non-lru movable page" to avoid that.

Thanks
Yisheng Xie.
>>  
>>  static inline int migrate_prep(void) { return -ENOSYS; }
>>  static inline int migrate_prep_local(void) { return -ENOSYS; }
>> -- 
>> 1.7.12.4
>>

Re: [PATCH] mm/migration: make isolate_movable_page always defined

[Minchan Kim]

On Wed, Jan 25, 2017 at 06:36:03PM +0800, Yisheng Xie wrote:
> Define isolate_movable_page as a static inline function when
> CONFIG_MIGRATION is not enable. It should return false
> here which means failed to isolate movable pages.
> 
> This patch do not have any functional change but to resolve compile
> error caused by former commit "HWPOISON: soft offlining for non-lru
> movable page" with CONFIG_MIGRATION disabled.
> 
> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Acked-by: Minchan Kim <minchan@kernel.org>