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[209.85.208.180]) by smtp.gmail.com with ESMTPSA id f21sm307525lfe.6.2021.01.13.12.00.53 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Jan 2021 12:00:53 -0800 (PST) Received: by mail-lj1-f180.google.com with SMTP id u11so3906442ljo.13 for ; Wed, 13 Jan 2021 12:00:53 -0800 (PST) X-Received: by 2002:a19:f014:: with SMTP id p20mr1485833lfc.421.1610567700198; Wed, 13 Jan 2021 11:55:00 -0800 (PST) MIME-Version: 1.0 References: <45806a5a-65c2-67ce-fc92-dc8c2144d766@nvidia.com> <20210113021619.GL35215@casper.infradead.org> <20210113123232.62vv6xsrpitne7hc@box> <20210113125532.GN35215@casper.infradead.org> In-Reply-To: <20210113125532.GN35215@casper.infradead.org> From: Linus Torvalds Date: Wed, 13 Jan 2021 11:54:44 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 0/1] mm: restore full accuracy in COW page reuse To: Matthew Wilcox Cc: "Kirill A. Shutemov" , John Hubbard , Andrea Arcangeli , Andrew Morton , Linux-MM , Linux Kernel Mailing List , Yu Zhao , Andy Lutomirski , Peter Xu , Pavel Emelyanov , Mike Kravetz , Mike Rapoport , Minchan Kim , Will Deacon , Peter Zijlstra , Hugh Dickins , Oleg Nesterov , Jann Horn , Kees Cook , Leon Romanovsky , Jason Gunthorpe , Jan Kara , Kirill Tkhai , Nadav Amit , Jens Axboe Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jan 13, 2021 at 4:56 AM Matthew Wilcox wrote: > > Yes, Linus mis-stated it: Yeah, I got the order wrong. > ... but as David pointed out, I fixed this in e320d3012d25 .. and I must have seen it, but not really internalized it. And now that I look at it more closely, I'm actually surprised that other than the magic "speculative first page" case we don't seem to use page reference counting for non-order-0 pages (which would break that hack horribly). Linus