From: "Zi Yan" <zi.yan@sent.com>
To: "Michal Hocko" <mhocko@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
"Naoya Horiguchi" <n-horiguchi@ah.jp.nec.com>,
linux-mm@kvack.org, "Andrew Morton" <akpm@linux-foundation.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page
Date: Thu, 05 Apr 2018 15:09:14 -0400 [thread overview]
Message-ID: <D2A2BB95-6D1D-487D-9CCA-FC66CE42B03D@sent.com> (raw)
In-Reply-To: <20180405190405.GS6312@dhcp22.suse.cz>
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On 5 Apr 2018, at 15:04, Michal Hocko wrote:
> On Thu 05-04-18 13:58:43, Zi Yan wrote:
>> 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?
>>>>>>> rmap_walk_file?
>>>>>>
>>>>>> 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:
>
> Good point. Except I would prefer a less convoluted condition
>
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 60531108021a..b4087aa890f5 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -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))) &&
>> + PageTransHuge(page))
>> return -ENOMEM;
>
> What about this?
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 5d0dc7b85f90..cd02e2bdf37c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1138,7 +1138,11 @@ 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))
> + /*
> + * THP pagecache or generally non-migrateable THP need to be split
> + * up before migration
> + */
> + if (PageTransHuge(page) && (!thp_migration_supported() || !PageAnon(page)))
> return -ENOMEM;
>
> newpage = get_new_page(page, private);
I think it works and is better than mine.
Reviewed-by: Zi Yan <zi.yan@cs.rutgers.edu>
--
Best Regards
Yan Zi
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next prev parent reply other threads:[~2018-04-05 19:09 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-03 4:46 [PATCH v1] mm: consider non-anonymous thp as unmovable page Naoya Horiguchi
2018-04-03 7:59 ` Michal Hocko
2018-04-03 8:24 ` Naoya Horiguchi
2018-04-03 8:34 ` Michal Hocko
2018-04-03 10:54 ` Kirill A. Shutemov
2018-04-03 10:58 ` Michal Hocko
2018-04-03 11:16 ` Kirill A. Shutemov
2018-04-03 11:33 ` Michal Hocko
2018-04-05 8:59 ` Michal Hocko
2018-04-05 12:28 ` Kirill A. Shutemov
2018-04-05 12:48 ` Michal Hocko
2018-04-05 13:40 ` Kirill A. Shutemov
2018-04-05 15:05 ` Michal Hocko
2018-04-05 15:55 ` Kirill A. Shutemov
2018-04-05 16:03 ` Michal Hocko
2018-04-05 17:58 ` Zi Yan
2018-04-05 19:04 ` Michal Hocko
2018-04-05 19:09 ` Zi Yan [this message]
2018-04-06 3:07 ` [PATCH] mm: shmem: enable thp migration (Re: [PATCH v1] mm: consider non-anonymous thp as unmovable page) Naoya Horiguchi
2018-04-06 5:14 ` Naoya Horiguchi
2018-04-06 7:08 ` Michal Hocko
2018-04-09 7:14 ` Naoya Horiguchi
2018-04-10 11:16 ` Kirill A. Shutemov
2018-04-11 9:26 ` Michal Hocko
2018-04-11 19:27 ` Andrew Morton
2018-04-11 19:43 ` Michal Hocko
2018-04-23 3:03 ` Matthew Wilcox
2018-04-23 7:21 ` Naoya Horiguchi
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