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=-5.8 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 9AA6BC4320A for ; Tue, 10 Aug 2021 09:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7F89060C51 for ; Tue, 10 Aug 2021 09:04:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238573AbhHJJFH (ORCPT ); Tue, 10 Aug 2021 05:05:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236131AbhHJJFG (ORCPT ); Tue, 10 Aug 2021 05:05:06 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93194C0613D3; Tue, 10 Aug 2021 02:04:43 -0700 (PDT) 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=pGywPtlb02K2MUVV2HEHzmAKnpUiArQRaAog4riS5J8=; b=iTHsqIAAqpgflDVlby2h8YiZ7U p/kAUBc7LEUTLIAHOW8BDox9+/2R4fl317sf1Qn/IbGXZxlun78eSuTeP1GsBozx432gsmWC6AYaT thI66A9wRdUiIWz+P3/MPi+MxRboOmRIlsjZn067uC1Qx9sNRGhdsWDUinDbgCYJifYtk9Rz8LOtE 2aqNzPNf9jmtEm2IYeIc5a4GD3KD38/LkvWDf2SZpmTaq5b3NlA7YUgQRJ0yrYw+YDjs3UUQoFyNr jE9/FzHb1LIvlQyGDg+1sxdymZFC4BQ0eMv+zWj6AqrFhcGnCnE/Uq3OWFd+TbujwI6vg4F5qixsW FUnBi1Ww==; Received: from [2001:4bb8:184:6215:a004:cea2:5ea9:6eca] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mDNg4-00BvMQ-HA; Tue, 10 Aug 2021 09:04:19 +0000 Date: Tue, 10 Aug 2021 11:04:03 +0200 From: Christoph Hellwig To: Alex Williamson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, jgg@nvidia.com, peterx@redhat.com Subject: Re: [PATCH 6/7] vfio: Add vfio_device_io_remap_mapping_range() Message-ID: References: <162818167535.1511194.6614962507750594786.stgit@omen> <162818329235.1511194.15804833796430403640.stgit@omen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <162818329235.1511194.15804833796430403640.stgit@omen> 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-kernel@vger.kernel.org > +int vfio_device_io_remap_mapping_range(struct vfio_device *device, > + loff_t start, loff_t len) > +{ > + struct address_space *mapping = device->inode->i_mapping; > + int ret = 0; > + > + i_mmap_lock_write(mapping); > + if (mapping_mapped(mapping)) { > + struct rb_root_cached *root = &mapping->i_mmap; > + pgoff_t pgstart = start >> PAGE_SHIFT; > + pgoff_t pgend = (start + len - 1) >> PAGE_SHIFT; > + struct vm_area_struct *vma; > + > + vma_interval_tree_foreach(vma, root, pgstart, pgend) { There is no need for the mapping_mapped check here, vma_interval_tree_foreach will the right thing for an empty tree. That also allows to move a few more instructions out of the lock. > + /* > + * Force NOFS memory allocation context to avoid > + * deadlock while we hold i_mmap_rwsem. > + */ > + flags = memalloc_nofs_save(); Please move this out of the loop. > +extern int vfio_device_io_remap_mapping_range(struct vfio_device *device, > + loff_t start, loff_t len); No need for the extern.