linux-kernel - Re: [PATCH 11/12] mm, thp, tmpfs: enable thp page cache in tmpfs

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Message-ID: <CACz4_2cGdGLs6PPT6ERf3dU32PRKh6Jr+6QTJA9kvOQP-uQP9g@mail.gmail.com>
Date:	Fri, 18 Oct 2013 15:16:09 -0700
From:	Ning Qu <quning@...gle.com>
To:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Al Viro <viro@...iv.linux.org.uk>,
	Wu Fengguang <fengguang.wu@...el.com>, Jan Kara <jack@...e.cz>,
	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	Andi Kleen <ak@...ux.intel.com>,
	Matthew Wilcox <willy@...ux.intel.com>,
	Hillf Danton <dhillf@...il.com>, Dave Hansen <dave@...1.net>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/12] mm, thp, tmpfs: enable thp page cache in tmpfs

Hi, Kirill,

I have reviewed the current migration code and seems huge page will
get splitted during migration. Since our current split_huge_page
handle file cache as well, it seems not a problem for us?

We just simply not removing the __GFP_MOVABLE flag? Anything else I am
missing here?

Thanks!
Best wishes,
-- 
Ning Qu (曲宁) | Software Engineer | quning@...gle.com | +1-408-418-6066


On Fri, Oct 18, 2013 at 11:24 AM, Ning Qu <quning@...gle.com> wrote:
> I guess this is the last review I have for this around, but not sure
> what's the best solution right now.
>
> Kirill, do you think it's OK to just split the huge page when it will
> be moved. Will look into how thp anon handle this situation.
>
> Then after this, I probably will post v2.
>
> Thanks!
> Best wishes,
> --
> Ning Qu (曲宁) | Software Engineer | quning@...gle.com | +1-408-418-6066
>
>
> On Tue, Oct 15, 2013 at 11:42 AM, Ning Qu <quning@...gle.com> wrote:
>> I agree with this. It has been like this just for a quick proof, but I
>> need to address this problem as soon as possible.
>>
>> Thanks!
>> Best wishes,
>> --
>> Ning Qu (曲宁) | Software Engineer | quning@...gle.com | +1-408-418-6066
>>
>>
>> On Tue, Oct 15, 2013 at 4:09 AM, Kirill A. Shutemov
>> <kirill.shutemov@...ux.intel.com> wrote:
>>> Ning Qu wrote:
>>>> Signed-off-by: Ning Qu <quning@...il.com>
>>>> ---
>>>>  mm/Kconfig | 4 ++--
>>>>  mm/shmem.c | 5 +++++
>>>>  2 files changed, 7 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/mm/Kconfig b/mm/Kconfig
>>>> index 562f12f..4d2f90f 100644
>>>> --- a/mm/Kconfig
>>>> +++ b/mm/Kconfig
>>>> @@ -428,8 +428,8 @@ config TRANSPARENT_HUGEPAGE_PAGECACHE
>>>>       help
>>>>         Enabling the option adds support hugepages for file-backed
>>>>         mappings. It requires transparent hugepage support from
>>>> -       filesystem side. For now, the only filesystem which supports
>>>> -       hugepages is ramfs.
>>>> +       filesystem side. For now, the filesystems which support
>>>> +       hugepages are: ramfs and tmpfs.
>>>>
>>>>  config CROSS_MEMORY_ATTACH
>>>>       bool "Cross Memory Support"
>>>> diff --git a/mm/shmem.c b/mm/shmem.c
>>>> index 75c0ac6..50a3335 100644
>>>> --- a/mm/shmem.c
>>>> +++ b/mm/shmem.c
>>>> @@ -1672,6 +1672,11 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
>>>>                       break;
>>>>               case S_IFREG:
>>>>                       inode->i_mapping->a_ops = &shmem_aops;
>>>> +                     /*
>>>> +                      * TODO: make tmpfs pages movable
>>>> +                      */
>>>> +                     mapping_set_gfp_mask(inode->i_mapping,
>>>> +                                          GFP_TRANSHUGE & ~__GFP_MOVABLE);
>>>
>>> Unlike ramfs, tmpfs pages are movable before transparent page cache
>>> patchset.
>>> Making tmpfs pages non-movable looks like a big regression to me. It need
>>> to be fixed before proposing it upstream.
>>>
>>> --
>>>  Kirill A. Shutemov
--
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