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=-0.8 required=3.0 tests=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 BCD15C43331 for ; Sat, 28 Mar 2020 15:37:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66B7920748 for ; Sat, 28 Mar 2020 15:37:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726899AbgC1Phb (ORCPT ); Sat, 28 Mar 2020 11:37:31 -0400 Received: from netrider.rowland.org ([192.131.102.5]:47179 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1726403AbgC1Phb (ORCPT ); Sat, 28 Mar 2020 11:37:31 -0400 Received: (qmail 1783 invoked by uid 500); 28 Mar 2020 11:37:30 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 28 Mar 2020 11:37:30 -0400 Date: Sat, 28 Mar 2020 11:37:30 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: John Donnelly cc: linux-usb@vger.kernel.org Subject: Re: ehci-pci : WARNING: CPU: 0 PID: 347 at kernel/dma/direct.c:34 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, 27 Mar 2020, John Donnelly wrote: > Hi, > > I am seeing this WARNING event with iommu=off when booting a DL380 > server with a 5.4.17 kernel. ... > The end result is this USB port is not configured when > dma_direct_map_page() is called and it returns return > DMA_MAPPING_ERROR; > > > When I boot the server with iommu=on I don’t see this sequence : ... > On an older kernel 5.3. flavor I am not seeing this behavior, and the usbhib devices appear as expected : I forgot to mention: Since you have one kernel where the WARNING occurs and one where it doesn't, you can use bisection to find the commit that was responsible for the change in behavior. If you care to go to the trouble... Alan Stern