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From: Matthew Wilcox <willy@infradead.org>
To: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>,
	Ryan Roberts <ryan.roberts@arm.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-doc@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Hugh Dickins <hughd@google.com>,
	Yin Fengwei <fengwei.yin@intel.com>,
	Yang Shi <shy828301@gmail.com>, Zi Yan <ziy@nvidia.com>
Subject: Re: [PATCH mm-unstable v1] mm: add a total mapcount for large folios
Date: Thu, 10 Aug 2023 22:48:41 +0100	[thread overview]
Message-ID: <ZNVbObUGbos73ZJ5@casper.infradead.org> (raw)
In-Reply-To: <ZNVPJ9xxd2oarR3I@x1n>

On Thu, Aug 10, 2023 at 04:57:11PM -0400, Peter Xu wrote:
> AFAICS if that patch was all correct (while I'm not yet sure..), you can
> actually fit your new total mapcount field into page 1 so even avoid the
> extra cacheline access.  You can have a look: the trick is refcount for
> tail page 1 is still seems to be free on 32 bits (if that was your worry
> before).  Then it'll be very nice if to keep Hugh's counter all in tail 1.

No, refcount must be 0 on all tail pages.  We rely on this in many places
in the MM.


  reply	other threads:[~2023-08-10 21:48 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-09  8:32 [PATCH mm-unstable v1] mm: add a total mapcount for large folios David Hildenbrand
2023-08-09 15:45 ` Zi Yan
2023-08-09 19:07 ` Ryan Roberts
2023-08-09 19:17   ` David Hildenbrand
2023-08-10 10:40     ` Ryan Roberts
2023-08-10 11:14     ` David Hildenbrand
2023-08-10 11:27       ` David Hildenbrand
2023-08-10 11:32         ` David Hildenbrand
2023-08-10 11:35           ` Ryan Roberts
2023-08-09 19:21   ` Matthew Wilcox
2023-08-09 19:26     ` David Hildenbrand
2023-08-10  3:14       ` Yin Fengwei
2023-08-09 21:23 ` Peter Xu
2023-08-10  3:25   ` Matthew Wilcox
2023-08-10  8:37     ` David Hildenbrand
2023-08-10 21:48       ` Peter Xu
2023-08-10 21:54         ` Matthew Wilcox
2023-08-10 21:59           ` David Hildenbrand
2023-08-11 15:03             ` Peter Xu
2023-08-11 15:14               ` Zi Yan
2023-08-11 15:17               ` David Hildenbrand
2023-08-10  8:59   ` David Hildenbrand
2023-08-10 10:48     ` Ryan Roberts
2023-08-10 17:15       ` Peter Xu
2023-08-10 17:47         ` David Hildenbrand
2023-08-10 19:02           ` Ryan Roberts
2023-08-10 20:57           ` Peter Xu
2023-08-10 21:48             ` Matthew Wilcox [this message]
2023-08-10 22:27               ` David Hildenbrand
2023-08-11 15:18                 ` Peter Xu
2023-08-11 15:32                   ` David Hildenbrand
2023-08-11 15:58                     ` Peter Xu
2023-08-11 16:08                       ` David Hildenbrand
2023-08-11 16:11                         ` Zi Yan
2023-08-11 22:18                           ` Peter Xu
2023-08-10 22:16             ` David Hildenbrand
2023-08-10  3:24 ` Yin Fengwei

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