Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page
From: Zi Yan
Date: Thu Apr 05 2018 - 13:58:52 EST
On 5 Apr 2018, at 12:03, Michal Hocko wrote:
> On Thu 05-04-18 18:55:51, Kirill A. Shutemov wrote:
>> On Thu, Apr 05, 2018 at 05:05:47PM +0200, Michal Hocko wrote:
>>> On Thu 05-04-18 16:40:45, Kirill A. Shutemov wrote:
>>>> On Thu, Apr 05, 2018 at 02:48:30PM +0200, Michal Hocko wrote:
>>>>> RIght, I confused the two. What is the proper layer to fix that then?
>>>> Maybe something like this? Totally untested.
>>> This looks way too complex. Why cannot we simply split THP page cache
>>> during migration?
>> This way we unify the codepath for archictures that don't support THP
>> migration and shmem THP.
> But why? There shouldn't be really nothing to prevent THP (anon or
> shemem) to be migratable. If we cannot migrate it at once we can always
> split it. So why should we add another thp specific handling all over
> the place?
Then, it would be much easier if your "unclutter thp migration" patches is merged,
plus the patch below:
diff --git a/mm/migrate.c b/mm/migrate.c
index 60531108021a..b4087aa890f5 100644
@@ -1138,7 +1138,9 @@ static ICE_noinline int unmap_and_move(new_page_t get_new_page,
int rc = MIGRATEPAGE_SUCCESS;
struct page *newpage;
- if (!thp_migration_supported() && PageTransHuge(page))
+ if ((!thp_migration_supported() ||
+ (thp_migration_supported() && !PageAnon(page))) &&
newpage = get_new_page(page, private)
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