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[209.85.167.41]) by smtp.gmail.com with ESMTPSA id z27sm179329lfg.14.2020.09.17.15.25.51 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Sep 2020 15:25:52 -0700 (PDT) Received: by mail-lf1-f41.google.com with SMTP id y17so3924312lfa.8 for ; Thu, 17 Sep 2020 15:25:51 -0700 (PDT) X-Received: by 2002:a19:521a:: with SMTP id m26mr11015777lfb.133.1600381551270; Thu, 17 Sep 2020 15:25:51 -0700 (PDT) MIME-Version: 1.0 References: <20200916174804.GC8409@ziepe.ca> <20200916184619.GB40154@xz-x1> <20200917112538.GD8409@ziepe.ca> <20200917181411.GA133226@xz-x1> <20200917190332.GB133226@xz-x1> <20200917200638.GM8409@ziepe.ca> <20200917214059.GA162800@xz-x1> <20200917220900.GO8409@ziepe.ca> In-Reply-To: <20200917220900.GO8409@ziepe.ca> From: Linus Torvalds Date: Thu, 17 Sep 2020 15:25:35 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 1/4] mm: Trial do_wp_page() simplification To: Jason Gunthorpe Cc: Peter Xu , John Hubbard , Leon Romanovsky , Linux-MM , Linux Kernel Mailing List , "Maya B . Gokhale" , Yang Shi , Marty Mcfadden , Kirill Shutemov , Oleg Nesterov , Jann Horn , Jan Kara , Kirill Tkhai , Andrea Arcangeli , Christoph Hellwig , 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 Thu, Sep 17, 2020 at 3:09 PM Jason Gunthorpe wrote: > > My advice for this -rc fix is to go with a single bit in the mm_struct > set on any call to pin_user_pages* Ack, except make sure it's a byte rather than a bitfield that could have races. Or even just a separate atomic_t. Keep it simple ans stupid and obvious. As you say, we can aim for cleanups later, make it obvious and reliable right now. Linus