From: Matthew Wilcox <willy@infradead.org>
To: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>,
gregkh@linuxfoundation.org, akpm@linux-foundation.org,
vbabka@suse.cz, dhowells@redhat.com, surenb@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
# see patch description <stable@vger.kernel.org>
Subject: Re: [PATCH] mm/huge_memory: fix swap entry values of tail pages of THP
Date: Wed, 14 Feb 2024 14:18:08 +0000 [thread overview]
Message-ID: <ZczLoOqdpMJpkO5N@casper.infradead.org> (raw)
In-Reply-To: <bc1a5e36-1983-1a39-4d06-8062993a4ca4@quicinc.com>
On Wed, Feb 14, 2024 at 12:04:10PM +0530, Charan Teja Kalla wrote:
> > 1) Is it broken in 5.15? Did you actually try to reproduce or is this
> > just a guess?
> >
>
> We didn't run the tests with THP enabled on 5.15, __so we didn't
> encounter this issue__ on older to 6.1 kernels.
>
> I mentioned that issue exists is based on my understanding after code
> walk through. To be specific, I just looked to the
> migrate_pages()->..->migrate_page_move_mapping() &
> __split_huge_page_tail() where the ->private field of thp sub-pages is
> not filled with swap entry. If it could have set, I think these are the
> only places where it would have done, per my understanding. CMIW.
I think you have a misunderstanding. David's patch cfeed8ffe55b (part
of 6.6) _stopped_ us using the tail ->private entries. So in 6.1, these
tail pages should already have page->private set, and I don't understand
what you're fixing.
> > 2) How did you come up with 417013e0d18 ("mm/migrate: Add
> > folio_migrate_mapping()")
> OOPS, I mean it is Fixes: 3417013e0d18 ("mm/migrate: Add
> folio_migrate_mapping()").
>
> My understanding is that it a miss in folio_migrate_mapping() where the
> sub-pages should've the ->private set. But this is just a
> reimplementation of migrate_page_move_mapping()(where also the issue
> exists, tmk).
>
> commit 3417013e0d183be9b42d794082eec0ec1c5b5f15
> Author: Matthew Wilcox (Oracle) <willy@infradead.org>
> Date: Fri May 7 07:28:40 2021 -0400
>
> mm/migrate: Add folio_migrate_mapping()
>
> Reimplement migrate_page_move_mapping() as a wrapper around
> folio_migrate_mapping(). Saves 193 bytes of kernel text.
>
> Thanks.
>
next prev parent reply other threads:[~2024-02-14 14:18 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-13 8:48 [PATCH] mm/huge_memory: fix swap entry values of tail pages of THP Charan Teja Kalla
2024-02-13 8:54 ` Matthew Wilcox
2024-02-13 9:10 ` Charan Teja Kalla
2024-02-13 9:25 ` David Hildenbrand
2024-02-13 16:27 ` Charan Teja Kalla
2024-02-13 18:36 ` David Hildenbrand
2024-02-14 6:34 ` Charan Teja Kalla
2024-02-14 14:18 ` Matthew Wilcox [this message]
2024-02-14 14:34 ` David Hildenbrand
2024-02-27 14:11 ` David Hildenbrand
2024-02-27 14:52 ` Zi Yan
2024-02-27 15:01 ` David Hildenbrand
2024-02-27 15:20 ` Zi Yan
2024-02-27 16:15 ` Zi Yan
2024-02-28 15:36 ` Charan Teja Kalla
2024-03-04 10:48 ` Greg KH
2024-02-13 9:41 ` Greg KH
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=ZczLoOqdpMJpkO5N@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=david@redhat.com \
--cc=dhowells@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=quic_charante@quicinc.com \
--cc=stable@vger.kernel.org \
--cc=surenb@google.com \
--cc=vbabka@suse.cz \
/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).