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From: "Weiny, Ira" <ira.weiny@intel.com>
To: Ralph Campbell <rcampbell@nvidia.com>,
	Matthew Wilcox <willy@infradead.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.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: Tue, 23 Jul 2019 21:39:17 +0000	[thread overview]
Message-ID: <2807E5FD2F6FDA4886F6618EAC48510E79E2E610@CRSMSX101.amr.corp.intel.com> (raw)
In-Reply-To: <80dbf7fc-5c13-f43f-7b87-8273126562e9@nvidia.com>

> 
> On 7/22/19 4:08 AM, Matthew Wilcox wrote:
> > On Sun, Jul 21, 2019 at 10:13:45PM -0700, Ira Weiny wrote:
> >> 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.
> >>
> >> Was V1 of Ralphs patch ok?  It seemed ok to me.
> >
> > Yes, v1 was fine.  This seems like a regression.
> >
> 
> This is about what people find "easiest to understand" and so I'm not
> surprised that opinions differ.
> What if I post a v3 based on v1 but remove the _zd_pad_* variables that
> Christoph found misleading and add some more comments about how the
> different ZONE_DEVICE types use the 3 remaining words (basically the
> comment from v2)?

I'm ok with that...

Ira


  reply	other threads:[~2019-07-23 21:39 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 [this message]
2019-07-22  9:36     ` Christoph Hellwig
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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