linux-kernel - Re: [PATCH] mm/migration: make isolate_movable

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Date:   Wed, 25 Jan 2017 21:26:58 +0800
From:   Yisheng Xie <ysxie@...mail.com>
To:     Michal Hocko <mhocko@...nel.org>,
        Yisheng Xie <xieyisheng1@...wei.com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        n-horiguchi@...jp.nec.com, akpm@...ux-foundation.org,
        minchan@...nel.org, vbabka@...e.cz, guohanjun@...wei.com,
        qiuxishi@...wei.com
Subject: Re: [PATCH] mm/migration: make isolate_movable_page always defined


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@...wei.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
>>