From: Matthew Wilcox <willy@infradead.org>
To: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org, apopple@nvidia.com
Subject: Re: [PATCH v2 4/6] mm/migrate_device: convert __migrate_device_pages() to folios
Date: Fri, 16 Feb 2024 23:19:05 +0000 [thread overview]
Message-ID: <Zc_taXK-X-NYPQli@casper.infradead.org> (raw)
In-Reply-To: <71db0ad0-a385-8572-7bea-bb11f76a6345@oracle.com>
On Fri, Feb 16, 2024 at 02:00:31PM -0800, Sidhartha Kumar wrote:
> On 2/16/24 1:55 PM, Matthew Wilcox wrote:
> > On Fri, Feb 16, 2024 at 01:13:18PM -0800, Sidhartha Kumar wrote:
> > > Use migrate_pfn_to_folio() so we can work with folios directly in
> > > __migrate_device_pages().
> >
> > i don't understand why this would be correct if we have multipage
> > folios.
> >
>
> Alistair mentioned that he is working on order > 0 device page support so I
> was under the impression that currently device pages are only order 0.
That might well be true, but I'm *very* uncomfortable with doing a folio
conversion in core MM that won't work with large folios. We need to
consider what will happen with large device folios.
(for filesystems, I am less bothered. Individual filesystems control
whether they see large folios or not, and for lesser filesystems it may
never be worth converting them to support large folios)
next prev parent reply other threads:[~2024-02-16 23:19 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-16 21:13 [PATCH v2 1/6] mm/migrate: introduce migrate_pfn_to_folio() Sidhartha Kumar
2024-02-16 21:13 ` [PATCH v2 2/6] mm/migrate_device: further convert migrate_device_unmap() to folios Sidhartha Kumar
2024-02-16 21:51 ` Matthew Wilcox
2024-02-16 21:13 ` [PATCH v2 3/6] mm/migrate_device: further convert migrate_device_finalize() " Sidhartha Kumar
2024-02-16 21:13 ` [PATCH v2 4/6] mm/migrate_device: convert __migrate_device_pages() " Sidhartha Kumar
2024-02-16 21:55 ` Matthew Wilcox
2024-02-16 22:00 ` Sidhartha Kumar
2024-02-16 23:19 ` Matthew Wilcox [this message]
2024-02-19 9:49 ` Alistair Popple
2024-02-16 21:13 ` [PATCH v2 5/6] mm/migrate_device: convert migrate_device_coherent_page() to migrate_device_coherent_folio() Sidhartha Kumar
2024-02-16 21:13 ` [PATCH v2 6/6] mm/migrate_device: convert migrate_device_range() to folios Sidhartha Kumar
2024-02-16 21:50 ` [PATCH v2 1/6] mm/migrate: introduce migrate_pfn_to_folio() Matthew Wilcox
2024-02-16 22:03 ` Sidhartha Kumar
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