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[209.85.208.179]) by smtp.gmail.com with ESMTPSA id 23sm55054lft.122.2021.01.12.18.43.34 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jan 2021 18:43:34 -0800 (PST) Received: by mail-lj1-f179.google.com with SMTP id x23so847317lji.7 for ; Tue, 12 Jan 2021 18:43:34 -0800 (PST) X-Received: by 2002:a2e:9ad7:: with SMTP id p23mr936040ljj.465.1610505813763; Tue, 12 Jan 2021 18:43:33 -0800 (PST) MIME-Version: 1.0 References: <20210110004435.26382-1-aarcange@redhat.com> <45806a5a-65c2-67ce-fc92-dc8c2144d766@nvidia.com> <20210113021619.GL35215@casper.infradead.org> In-Reply-To: <20210113021619.GL35215@casper.infradead.org> From: Linus Torvalds Date: Tue, 12 Jan 2021 18:43:17 -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: 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 , "Kirill A. Shutemov" , 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 Tue, Jan 12, 2021 at 6:16 PM Matthew Wilcox wrote: > > The thing about the speculative page cache references is that they can > temporarily bump a refcount on a page which _used_ to be in the page > cache and has now been reallocated as some other kind of page. Right you are. Yeah, scratch the "we could make it absolute on 1", and we do need the PIN count elevation. Linus