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From: Christoph Hellwig <hch@lst.de>
To: Ralph Campbell <rcampbell@nvidia.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"John Hubbard" <jhubbard@nvidia.com>,
	"Matthew Wilcox" <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 v3 1/3] mm: document zone device struct page field usage
Date: Thu, 25 Jul 2019 07:38:21 +0200	[thread overview]
Message-ID: <20190725053821.GA24527@lst.de> (raw)
In-Reply-To: <20190724232700.23327-2-rcampbell@nvidia.com>

On Wed, Jul 24, 2019 at 04:26:58PM -0700, Ralph Campbell wrote:
> Struct page for ZONE_DEVICE private pages uses the page->mapping and
> and page->index fields while the source anonymous pages are migrated to
> device private memory. This is so rmap_walk() can find the page when
> migrating the ZONE_DEVICE private page back to system memory.
> ZONE_DEVICE pmem backed fsdax pages also use the page->mapping and
> page->index fields when files are mapped into a process address space.
> 
> Add comments to struct page and remove the unused "_zd_pad_1" field
> to make this more clear.

I still think we should also fix up the layout, and I haven't seen
a reply from Matthew justifying his curses for your patch that makes
the struct page layout actually match how it is used.


  parent reply	other threads:[~2019-07-25  5:38 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-24 23:26 [PATCH v3 0/3] mm/hmm: fixes for device private page migration Ralph Campbell
2019-07-24 23:26 ` [PATCH v3 1/3] mm: document zone device struct page field usage Ralph Campbell
2019-07-25  1:22   ` Jason Gunthorpe
2019-07-25 17:49     ` Ralph Campbell
2019-07-25  5:38   ` Christoph Hellwig [this message]
2019-07-25 18:19     ` Ralph Campbell
2019-07-24 23:26 ` [PATCH v3 2/3] mm/hmm: fix ZONE_DEVICE anon page mapping reuse Ralph Campbell
2019-08-02  8:31   ` Christoph Hellwig
2019-08-02 19:11     ` Andrew Morton
2019-07-24 23:27 ` [PATCH v3 3/3] mm/hmm: Fix bad subpage pointer in try_to_unmap_one Ralph Campbell
2019-07-25  2:03   ` Sasha Levin

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