From: Christoph Hellwig <hch@lst.de>
To: John Hubbard <jhubbard@nvidia.com>
Cc: "Ralph Campbell" <rcampbell@nvidia.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
willy@infradead.org, "Vlastimil Babka" <vbabka@suse.cz>,
"Christoph Lameter" <cl@linux.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
"Lai Jiangshan" <jiangshanlai@gmail.com>,
"Martin Schwidefsky" <schwidefsky@de.ibm.com>,
"Pekka Enberg" <penberg@kernel.org>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Andrey Ryabinin" <aryabinin@virtuozzo.com>,
"Christoph Hellwig" <hch@lst.de>,
"Jason Gunthorpe" <jgg@mellanox.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Linus Torvalds" <torvalds@linux-foundation.org>
Subject: Re: [PATCH 1/3] mm: document zone device struct page reserved fields
Date: Wed, 17 Jul 2019 06:22:33 +0200 [thread overview]
Message-ID: <20190717042233.GA4529@lst.de> (raw)
In-Reply-To: <26a47482-c736-22c4-c21b-eb5f82186363@nvidia.com>
On Tue, Jul 16, 2019 at 06:20:23PM -0700, John Hubbard wrote:
> > - unsigned long _zd_pad_1; /* uses mapping */
> > + /*
> > + * The following fields are used to hold the source
> > + * page anonymous mapping information while it is
> > + * migrated to device memory. See migrate_page().
> > + */
> > + unsigned long _zd_pad_1; /* aliases mapping */
> > + unsigned long _zd_pad_2; /* aliases index */
> > + unsigned long _zd_pad_3; /* aliases private */
>
> Actually, I do think this helps. It's hard to document these fields, and
> the ZONE_DEVICE pages have a really complicated situation during migration
> to a device.
>
> Additionally, I'm not sure, but should we go even further, and do this on the
> other side of the alias:
The _zd_pad_* field obviously are NOT used anywhere in the source tree.
So these comments are very misleading. If we still keep
using ->mapping, ->index and ->private we really should clean up the
definition of struct page to make that obvious instead of trying to
doctor around it using comments.
next prev parent reply other threads:[~2019-07-17 4:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 0:14 [PATCH 0/3] mm/hmm: fixes for device private page migration Ralph Campbell
2019-07-17 0:14 ` [PATCH 1/3] mm: document zone device struct page reserved fields Ralph Campbell
2019-07-17 1:20 ` John Hubbard
2019-07-17 4:22 ` Christoph Hellwig [this message]
2019-07-17 4:31 ` John Hubbard
2019-07-17 4:38 ` Christoph Hellwig
2019-07-17 17:50 ` Ralph Campbell
2019-07-17 0:14 ` [PATCH 2/3] mm/hmm: fix ZONE_DEVICE anon page mapping reuse Ralph Campbell
2019-07-17 1:40 ` John Hubbard
2019-07-17 0:14 ` [PATCH 3/3] mm/hmm: Fix bad subpage pointer in try_to_unmap_one Ralph Campbell
2019-07-17 1:51 ` John Hubbard
2019-07-17 15:14 ` Sasha Levin
-- strict thread matches above, loose matches on Subject: below --
2019-07-19 19:06 [PATCH 0/3] mm/hmm: fixes for device private page migration Ralph Campbell
2019-07-19 19:06 ` [PATCH 1/3] mm: document zone device struct page reserved fields Ralph Campbell
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=20190717042233.GA4529@lst.de \
--to=hch@lst.de \
--cc=akpm@linux-foundation.org \
--cc=aryabinin@virtuozzo.com \
--cc=cl@linux.com \
--cc=dave.hansen@linux.intel.com \
--cc=jgg@mellanox.com \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=jiangshanlai@gmail.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=rcampbell@nvidia.com \
--cc=rdunlap@infradead.org \
--cc=schwidefsky@de.ibm.com \
--cc=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.