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[209.85.167.53]) by smtp.gmail.com with ESMTPSA id e27sm2321405ljb.6.2021.01.08.11.25.38 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 Jan 2021 11:25:38 -0800 (PST) Received: by mail-lf1-f53.google.com with SMTP id o17so25562742lfg.4 for ; Fri, 08 Jan 2021 11:25:38 -0800 (PST) X-Received: by 2002:a2e:9b13:: with SMTP id u19mr2008203lji.48.1610133938011; Fri, 08 Jan 2021 11:25:38 -0800 (PST) MIME-Version: 1.0 References: <20210108124815.GA4512@willie-the-truck> In-Reply-To: From: Linus Torvalds Date: Fri, 8 Jan 2021 11:25:21 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/2] mm: soft_dirty: userfaultfd: introduce wrprotect_tlb_flush_pending To: Andrea Arcangeli Cc: Will Deacon , Linux-MM , Linux Kernel Mailing List , Yu Zhao , Andy Lutomirski , Peter Xu , Pavel Emelyanov , Mike Kravetz , Mike Rapoport , Minchan Kim , Peter Zijlstra , Hugh Dickins , "Kirill A. Shutemov" , Matthew Wilcox , Oleg Nesterov , Jann Horn , Kees Cook , John Hubbard , Leon Romanovsky , Jason Gunthorpe , Jan Kara , Kirill Tkhai , Nadav Amit , Andrew Morton 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 Fri, Jan 8, 2021 at 9:53 AM Andrea Arcangeli wrote: > > Do you intend to eventually fix the zygote vmsplice case or not? > Because in current upstream it's not fixed currently using the > enterprise default config. Is this the hugepage case? Neither of your patches actually touched that, so I've forgotten the details. > Irrelevant special case as in: long term GUP pin on the memory? Irrelevant special case in that (a) an extra COW shouldn't be a correctness issue unless somebody does something horribly wrong (and obviously the code that hasn't taken the mmap_lock for writing are then examples of that) and (b) it's not a performance issue either unless you can find a real load that does it. Hmm? Linus