linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Miaohe Lin <linmiaohe@huawei.com>
To: Yu Zhao <yuzhao@google.com>
Cc: <akpm@linux-foundation.org>, <hannes@cmpxchg.org>,
	<vbabka@suse.cz>, <mhocko@suse.com>, <axboe@kernel.dk>,
	<iamjoonsoo.kim@lge.com>, <alexs@kernel.org>,
	<apopple@nvidia.com>, <willy@infradead.org>, <minchan@kernel.org>,
	<david@redhat.com>, <shli@fb.com>, <hillf.zj@alibaba-inc.com>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/5] mm/vmscan: put the redirtied MADV_FREE pages back to anonymous LRU list
Date: Mon, 12 Jul 2021 15:11:55 +0800	[thread overview]
Message-ID: <022f2f7c-fc03-182a-1f8f-4b77c0731d4f@huawei.com> (raw)
In-Reply-To: <CAOUHufZpU4uQOBb4p10uCXs-40MeETRUmGiqy96Eim1w3o_dgQ@mail.gmail.com>

On 2021/7/11 7:22, Yu Zhao wrote:
> On Sat, Jul 10, 2021 at 4:03 AM Miaohe Lin <linmiaohe@huawei.com> wrote:
>>
>> If the MADV_FREE pages are redirtied before they could be reclaimed, put
>> the pages back to anonymous LRU list by setting SwapBacked flag and the
>> pages will be reclaimed in normal swapout way. Otherwise MADV_FREE pages
>> won't be reclaimed as expected.
>>
>> Fixes: 802a3a92ad7a ("mm: reclaim MADV_FREE pages")
> 
> This is not a bug -- the dirty check isn't needed but it was copied
> from __remove_mapping().

Yes, this is not a bug and harmless. When we reach here, page should not be
dirtied because PageDirty is handled above and there is no way to redirty it
again as pagetable references are all gone and it's not in the swap cache.

> 
> The page has only one reference left, which is from the isolation.
> After the caller puts the page back on lru and drops the reference,
> the page will be freed anyway. It doesn't matter which lru it goes.

But it looks buggy as it didn't perform the expected ops from code view.
Should I drop the Fixes tag and send a v2 version?

Many thanks for reply!

> 
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>>  mm/vmscan.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index a7602f71ec04..6483fe0e2065 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1628,6 +1628,7 @@ static unsigned int shrink_page_list(struct list_head *page_list,
>>                         if (!page_ref_freeze(page, 1))
>>                                 goto keep_locked;
>>                         if (PageDirty(page)) {
>> +                               SetPageSwapBacked(page);
>>                                 page_ref_unfreeze(page, 1);
>>                                 goto keep_locked;
>>                         }
>> --
>> 2.23.0
>>
>>
> .
> 


  reply	other threads:[~2021-07-12  7:50 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-10 10:03 [PATCH 0/5] Cleanup and fixup for vmscan Miaohe Lin
2021-07-10 10:03 ` [PATCH 1/5] mm/vmscan: put the redirtied MADV_FREE pages back to anonymous LRU list Miaohe Lin
2021-07-10 23:22   ` Yu Zhao
2021-07-12  7:11     ` Miaohe Lin [this message]
2021-07-13  7:25       ` Yu Zhao
2021-07-13 13:16         ` Miaohe Lin
2021-07-12  7:22   ` Michal Hocko
2021-07-12 11:03     ` Miaohe Lin
2021-07-13  9:30       ` Michal Hocko
2021-07-13 13:13         ` Miaohe Lin
2021-07-13 13:34           ` Matthew Wilcox
2021-07-14 11:36             ` Miaohe Lin
2021-07-14 11:48               ` Matthew Wilcox
2021-07-14 19:43                 ` John Hubbard
2021-07-15 11:30                   ` Miaohe Lin
2021-07-16  0:01                     ` John Hubbard
2021-07-16  1:53                       ` Miaohe Lin
2021-07-10 10:03 ` [PATCH 2/5] mm/vmscan: remove misleading setting to sc->priority Miaohe Lin
2021-07-12  7:24   ` Michal Hocko
2021-07-12 11:10     ` Miaohe Lin
2021-07-10 10:03 ` [PATCH 3/5] mm/vmscan: remove unneeded return value of kswapd_run() Miaohe Lin
2021-07-12  7:25   ` Michal Hocko
2021-07-10 10:03 ` [PATCH 4/5] mm/vmscan: add 'else' to remove check_pending label Miaohe Lin
2021-07-12  7:26   ` Michal Hocko
2021-07-10 10:03 ` [PATCH 5/5] mm/vmscan: fix misleading comment in isolate_lru_pages() Miaohe Lin
2021-07-12  7:28   ` Michal Hocko
2021-07-12 11:16     ` Miaohe Lin
2021-07-13  9:32       ` Michal Hocko
2021-07-13 12:50         ` Miaohe Lin

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=022f2f7c-fc03-182a-1f8f-4b77c0731d4f@huawei.com \
    --to=linmiaohe@huawei.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexs@kernel.org \
    --cc=apopple@nvidia.com \
    --cc=axboe@kernel.dk \
    --cc=david@redhat.com \
    --cc=hannes@cmpxchg.org \
    --cc=hillf.zj@alibaba-inc.com \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@suse.com \
    --cc=minchan@kernel.org \
    --cc=shli@fb.com \
    --cc=vbabka@suse.cz \
    --cc=willy@infradead.org \
    --cc=yuzhao@google.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).