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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 08F9EC00449 for ; Wed, 3 Oct 2018 20:00:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9233021470 for ; Wed, 3 Oct 2018 20:00:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="daxu2Bz/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9233021470 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727150AbeJDCuk (ORCPT ); Wed, 3 Oct 2018 22:50:40 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:49276 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726950AbeJDCuk (ORCPT ); Wed, 3 Oct 2018 22:50:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=WfaXDH1t/nqC3tS6Sr15KeWJZhsOtic+vDj0DqqzZw0=; b=daxu2Bz/x8FJAVzxWRz06l5+8 3Wr9Yj++I57WSPEJyTXOFF6v6frKPtgyOrxG1LtgWlsk61lJ4aTgHMw/Gi6g1hTWCyMnxXo3evPDr zZP6XGV8XE6r5stK8eiqA3ZkLzKrIcgGeE7IaorW+ThD1Uhl1qvgpICXAF78F1ylK6jBhX5sfNnS2 V1+i/vb9ai5ckTCJ7PnU46WtKgajk+QbLNoC6SUSt6NScSVAp2a1J9jDoBc7edoljIP4tnXaYYvPJ HVwxUbZnzHO5H9xp487Fyji6PYlDuF1NghO7zsHTyd4JoTQrVLK/vBHPKRxYczzd9L0C7ySk/4Ij3 N7cBX+OqQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1g7nJU-0004q9-KO; Wed, 03 Oct 2018 20:00:04 +0000 Date: Wed, 3 Oct 2018 13:00:03 -0700 From: Matthew Wilcox To: Souptick Joarder Cc: linux@armlinux.org.uk, miguel.ojeda.sandonis@gmail.com, robin@protonic.nl, stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, heiko@sntech.de, airlied@linux.ie, robin.murphy@arm.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, m.szyprowski@samsung.com, keescook@chromium.org, treding@nvidia.com, mhocko@suse.com, dan.j.williams@intel.com, kirill.shutemov@linux.intel.com, mark.rutland@arm.com, aryabinin@virtuozzo.com, dvyukov@google.com, kstewart@linuxfoundation.org, tchibo@google.com, riel@redhat.com, minchan@kernel.org, peterz@infradead.org, ying.huang@intel.com, ak@linux.intel.com, rppt@linux.vnet.ibm.com, linux@dominikbrodowski.net, arnd@arndb.de, cpandya@codeaurora.org, hannes@cmpxchg.org, joe@perches.com, mcgrof@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux1394-devel@lists.sourceforge.net, dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH v2] mm: Introduce new function vm_insert_kmem_page Message-ID: <20181003200003.GA9965@bombadil.infradead.org> References: <20181003185854.GA1174@jordon-HP-15-Notebook-PC> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181003185854.GA1174@jordon-HP-15-Notebook-PC> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 04, 2018 at 12:28:54AM +0530, Souptick Joarder wrote: > These are the approaches which could have been taken to handle > this scenario - > > * Replace vm_insert_page with vmf_insert_page and then write few > extra lines of code to convert VM_FAULT_CODE to errno which > makes driver users more complex ( also the reverse mapping errno to > VM_FAULT_CODE have been cleaned up as part of vm_fault_t migration , > not preferred to introduce anything similar again) > > * Maintain both vm_insert_page and vmf_insert_page and use it in > respective places. But it won't gurantee that vm_insert_page will > never be used in #PF context. > > * Introduce a similar API like vm_insert_page, convert all non #PF > consumer to use it and finally remove vm_insert_page by converting > it to vmf_insert_page. > > And the 3rd approach was taken by introducing vm_insert_kmem_page(). > > In short, vmf_insert_page will be used in page fault handlers > context and vm_insert_kmem_page will be used to map kernel > memory to user vma outside page fault handlers context. As far as I can tell, vm_insert_kmem_page() is line-for-line identical with vm_insert_page(). Seriously, here's a diff I just did: -static int insert_page(struct vm_area_struct *vma, unsigned long addr, - struct page *page, pgprot_t prot) +static int insert_kmem_page(struct vm_area_struct *vma, unsigned long addr, + struct page *page, pgprot_t prot) - /* Ok, finally just insert the thing.. */ -int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, +int vm_insert_kmem_page(struct vm_area_struct *vma, unsigned long addr, - return insert_page(vma, addr, page, vma->vm_page_prot); + return insert_kmem_page(vma, addr, page, vma->vm_page_prot); -EXPORT_SYMBOL(vm_insert_page); +EXPORT_SYMBOL(vm_insert_kmem_page); What on earth are you trying to do?