From: Wei Yang <richard.weiyang@gmail.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>,
Mika Penttil?? <mika.penttila@nextfour.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
Zi Yan <ziy@nvidia.com>, Michal Hocko <mhocko@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Minchan Kim <minchan@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>
Subject: Re: [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE
Date: Mon, 16 Mar 2020 22:38:14 +0000 [thread overview]
Message-ID: <20200316223814.dpzlmfpb6a2cus25@master> (raw)
In-Reply-To: <87pnddrt5t.fsf@yhuang-dev.intel.com>
On Mon, Mar 16, 2020 at 09:21:34AM +0800, Huang, Ying wrote:
>Wei Yang <richard.weiyang@gmail.com> writes:
>
>> On Sun, Mar 15, 2020 at 10:54:03AM +0200, Mika Penttil?? wrote:
>>>
>>>
>>>On 15.3.2020 10.18, Wei Yang wrote:
>>>> On Fri, Feb 28, 2020 at 11:38:18AM +0800, Huang, Ying wrote:
>>>> > From: Huang Ying <ying.huang@intel.com>
>>>> >
>>>> > Now !PageSwapBacked() is used as the flag for the pages freed lazily
>>>> > via MADV_FREE. This isn't obvious enough. So Dave suggested to add a
>>>> > new page flag for that to improve the code readability.
>>>> I am confused with the usage of PageSwapBacked().
>>>>
>>>> Previously I thought this flag means the page is swapin, set in
>>>> swapin_readahead(). While I found page_add_new_anon_rmap() would set it too.
>>>> This means every anon page would carry this flag. Then what is this flag
>>>> means?
>>>>
>>>>
>>>
>>>But not all PageSwapBacked() pages are anon, like shmem.
>>>
>>
>> Yes, while it looks shmem is the only exception.
>
>Another exception is the pages freed lazily via MADV_FREE.
>
>> I am still struggling to understand the meaning of this flag.
>
>You can use `git blame` to find out the commit which introduces this
>flag. Which describes why this flag is introduced.
Thanks, I see the purpose is to distinguish a page:
a) file backed
b) or otheres
This sound more clear.
And now this flag is also used for MADV_FREE, which sounds a little abuse.
This is the purpose of this patch to make a dedicate flag for MADV_FREE.
BTW, the name, swapbacked, is a little misleading. Maybe just to me. But I
can't come up with better naming. :-)
>
>Best Regards,
>Huang, Ying
>
>>>
>>>--Mika
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2020-03-16 22:38 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 3:38 [RFC 0/3] mm: Discard lazily freed pages when migrating Huang, Ying
2020-02-28 3:38 ` [RFC 1/3] mm, migrate: Check return value of try_to_unmap() Huang, Ying
2020-02-28 3:38 ` [RFC 2/3] mm: Add a new page flag PageLayzyFree() for MADV_FREE Huang, Ying
2020-02-28 6:13 ` David Hildenbrand
2020-02-28 6:47 ` Huang, Ying
2020-03-15 8:18 ` Wei Yang
2020-03-15 8:54 ` Mika Penttilä
2020-03-15 12:22 ` Wei Yang
2020-03-16 1:21 ` Huang, Ying
2020-03-16 22:38 ` Wei Yang [this message]
2020-02-28 3:38 ` [RFC 3/3] mm: Discard lazily freed pages when migrating Huang, Ying
2020-02-28 3:42 ` [RFC 0/3] " Matthew Wilcox
2020-02-28 7:25 ` Huang, Ying
2020-02-28 8:22 ` David Hildenbrand
2020-02-28 8:55 ` Huang, Ying
2020-02-28 9:49 ` Mel Gorman
2020-03-02 11:23 ` Huang, Ying
2020-03-02 15:16 ` Mel Gorman
2020-03-03 1:51 ` Huang, Ying
2020-03-03 8:09 ` Michal Hocko
2020-03-03 8:47 ` Huang, Ying
2020-03-03 8:58 ` Michal Hocko
2020-03-03 11:49 ` Huang, Ying
2020-03-04 9:58 ` Michal Hocko
2020-03-04 10:56 ` Mel Gorman
2020-03-05 1:42 ` Huang, Ying
2020-03-04 11:15 ` Huang, Ying
2020-03-04 11:26 ` Michal Hocko
2020-03-05 1:45 ` Huang, Ying
2020-03-05 10:48 ` Mel Gorman
2020-03-06 4:05 ` Huang, Ying
2020-03-09 5:26 ` Huang, Ying
2020-03-03 13:02 ` Mel Gorman
2020-03-04 0:33 ` Huang, Ying
2020-02-28 9:50 ` Michal Hocko
2020-02-28 10:15 ` Michal Hocko
2020-02-28 13:45 ` Johannes Weiner
2020-03-02 14:12 ` Huang, Ying
2020-03-02 14:23 ` David Hildenbrand
2020-03-03 0:25 ` Huang, Ying
2020-03-02 14:25 ` Michal Hocko
2020-03-03 1:30 ` Huang, Ying
2020-03-03 8:19 ` Michal Hocko
2020-03-03 11:36 ` Huang, Ying
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200316223814.dpzlmfpb6a2cus25@master \
--to=richard.weiyang@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=dave.hansen@linux.intel.com \
--cc=david@redhat.com \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=mhocko@kernel.org \
--cc=mika.penttila@nextfour.com \
--cc=minchan@kernel.org \
--cc=peterz@infradead.org \
--cc=vbabka@suse.cz \
--cc=ying.huang@intel.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).