From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B0F8C00A89 for ; Mon, 2 Nov 2020 16:41:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F5BE22275 for ; Mon, 2 Nov 2020 16:41:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nE3J0Pfg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727266AbgKBQlk (ORCPT ); Mon, 2 Nov 2020 11:41:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41330 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727202AbgKBQlk (ORCPT ); Mon, 2 Nov 2020 11:41:40 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31786C0617A6; Mon, 2 Nov 2020 08:41:40 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ytzVAE2XCkwajxNhr8bJkGONDthc4ed0WgNEJDU139o=; b=nE3J0Pfg3W6SPnONobv6XQp1hy owdsSlNiW+Y+bXs25cf+31F3D+mxsgHuDIuqdWfnAnRlHJ1s5R+ctP8rcgh+DxSSBBpSXd6axdU4J sRMEd3Y+YpSCakvhT0EkTeN6kVU5UD1aRFi6OCuHy5CgoyGRpl+5R238VwjWhH7cwoyPEK4yiZ1X6 Cgs3zHL/wjscvr7GJ1R0kxcjsQaBy+BbvD8cAQG1QY+FZNbFHH3KZDCtM7wOsPa/epJ2/S6Z4tq1E eqqc5m7o1oaEZFRUN2OlMu229aZwM0UmKcHYyLco2iOqHMFfV7rvlyxhX+6qaKX5md8tUWMzty3Ex sDCyYxGQ==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZctf-0006jm-CW; Mon, 02 Nov 2020 16:41:31 +0000 Date: Mon, 2 Nov 2020 16:41:31 +0000 From: Christoph Hellwig To: Jason Gunthorpe Cc: Daniel Vetter , Christoph Hellwig , DRI Development , LKML , KVM list , Linux MM , Linux ARM , linux-samsung-soc , "open list:DMA BUFFER SHARING FRAMEWORK" , Daniel Vetter , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , J??r??me Glisse , Jan Kara Subject: Re: [PATCH v5 08/15] mm: Add unsafe_follow_pfn Message-ID: <20201102164131.GA25526@infradead.org> References: <20201030100815.2269-1-daniel.vetter@ffwll.ch> <20201030100815.2269-9-daniel.vetter@ffwll.ch> <20201102072931.GA16419@infradead.org> <20201102130115.GC36674@ziepe.ca> <20201102155256.GG36674@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201102155256.GG36674@ziepe.ca> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-samsung-soc@vger.kernel.org On Mon, Nov 02, 2020 at 11:52:56AM -0400, Jason Gunthorpe wrote: > Need to hold the lock to check that and there are two ways to register > notifiers these days, so it feels to expensive to me. > > CH's 'export symbol only for kvm' really does seem the most robust way > to handle this though. I hope I can get that done for this merge window, but I'm not sure. I still think we should at least have a new name for the old follow_pfn that no one should use. And it should sound more scary than unsafe_follow_pfn :)