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[209.85.220.65]) by mx.google.com with SMTPS id u62sor47142418qkf.94.2019.08.06.06.37.06 for (Google Transport Security); Tue, 06 Aug 2019 06:37:06 -0700 (PDT) Received-SPF: pass (google.com: domain of mst@redhat.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mst@redhat.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=mst@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com X-Google-Smtp-Source: APXvYqwQogResfBtEcBuAcFTuCtTWGzeNFF/0eeIOxkxJPkA8JpnI8WBDTcUIzFbb3AvBDILVnFfYQ== X-Received: by 2002:ae9:efc6:: with SMTP id d189mr2946499qkg.323.1565098625407; Tue, 06 Aug 2019 06:37:05 -0700 (PDT) Received: from redhat.com ([147.234.38.1]) by smtp.gmail.com with ESMTPSA id q73sm24068906qke.90.2019.08.06.06.37.01 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 06 Aug 2019 06:37:04 -0700 (PDT) Date: Tue, 6 Aug 2019 09:36:58 -0400 From: "Michael S. Tsirkin" To: Jason Gunthorpe Cc: Jason Wang , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH V2 7/9] vhost: do not use RCU to synchronize MMU notifier with worker Message-ID: <20190806093633-mutt-send-email-mst@kernel.org> References: <20190801141512.GB23899@ziepe.ca> <42ead87b-1749-4c73-cbe4-29dbeb945041@redhat.com> <20190802124613.GA11245@ziepe.ca> <20190802100414-mutt-send-email-mst@kernel.org> <20190802172418.GB11245@ziepe.ca> <20190803172944-mutt-send-email-mst@kernel.org> <20190804001400.GA25543@ziepe.ca> <20190804040034-mutt-send-email-mst@kernel.org> <20190806115317.GA11627@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190806115317.GA11627@ziepe.ca> 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, Aug 06, 2019 at 08:53:17AM -0300, Jason Gunthorpe wrote: > On Sun, Aug 04, 2019 at 04:07:17AM -0400, Michael S. Tsirkin wrote: > > > > > Also, why can't this just permanently GUP the pages? In fact, where > > > > > does it put_page them anyhow? Worrying that 7f466 adds a get_user page > > > > > but does not add a put_page?? > > > > > > You didn't answer this.. Why not just use GUP? > > > > > > Jason > > > > Sorry I misunderstood the question. Permanent GUP breaks lots of > > functionality we need such as THP and numa balancing. > > Really? It doesn't look like that many pages are involved.. > > Jason Yea. But they just might happen to be heavily accessed ones.... -- MST