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From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Ralph Campbell" <rcampbell@nvidia.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"John Hubbard" <jhubbard@nvidia.com>,
	"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 v2 1/3] mm: document zone device struct page field usage
Date: Mon, 22 Jul 2019 11:36:56 +0200	[thread overview]
Message-ID: <20190722093656.GD29538@lst.de> (raw)
In-Reply-To: <20190721160204.GB363@bombadil.infradead.org>

On Sun, Jul 21, 2019 at 09:02:04AM -0700, Matthew Wilcox wrote:
> On Fri, Jul 19, 2019 at 12:29:53PM -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.
> > 
> > Restructure struct page and add comments to make this more clear.
> 
> NAK.  I just got rid of this kind of foolishness from struct page,
> and you're making it harder to understand, not easier.  The comments
> could be improved, but don't lay it out like this again.

This comes over pretty agressive.  Please explain how making the
layout match how the code actually is used vs the previous separation
that is actively misleading and confused multiple people is "foolishness".

  parent reply	other threads:[~2019-07-22  9:37 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19 19:29 [PATCH v2 0/3] mm/hmm: fixes for device private page migration Ralph Campbell
2019-07-19 19:29 ` [PATCH v2 1/3] mm: document zone device struct page field usage Ralph Campbell
2019-07-19 21:43   ` John Hubbard
2019-07-21 15:05   ` Randy Dunlap
2019-07-21 16:02   ` Matthew Wilcox
2019-07-22  5:13     ` Ira Weiny
2019-07-22 11:08       ` Matthew Wilcox
2019-07-23 21:25         ` Ralph Campbell
2019-07-23 21:39           ` Weiny, Ira
2019-07-22  9:36     ` Christoph Hellwig [this message]
2019-07-22  9:37   ` Christoph Hellwig
2019-07-19 19:29 ` [PATCH v2 2/3] mm/hmm: fix ZONE_DEVICE anon page mapping reuse Ralph Campbell
2019-07-19 21:45   ` John Hubbard
2019-07-22  9:38   ` Christoph Hellwig
2019-07-19 19:29 ` [PATCH v2 3/3] mm/hmm: Fix bad subpage pointer in try_to_unmap_one Ralph Campbell

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