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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 A87ADC46470 for ; Wed, 22 May 2019 06:31:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 831EC21872 for ; Wed, 22 May 2019 06:31:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728263AbfEVGbq (ORCPT ); Wed, 22 May 2019 02:31:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:43612 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725796AbfEVGbq (ORCPT ); Wed, 22 May 2019 02:31:46 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B08E1B01F; Wed, 22 May 2019 06:31:44 +0000 (UTC) Message-ID: <1558506702.12672.28.camel@suse.com> Subject: Re: [RFC PATCH] usb: host: xhci: allow __GFP_FS in dma allocation From: Oliver Neukum To: Alan Stern Cc: Jaewon Kim , Christoph Hellwig , linux-mm@kvack.org, gregkh@linuxfoundation.org, Jaewon Kim , m.szyprowski@samsung.com, ytk.lee@samsung.com, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Date: Wed, 22 May 2019 08:31:42 +0200 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Di, 2019-05-21 at 10:00 -0400, Alan Stern wrote: > > Changing configurations amounts to much the same as disconnecting, > because both operations destroy all the existing interfaces. > > Disconnect can arise in two different ways. > > Physical hot-unplug: All I/O operations will fail. > > Rmmod or unbind: I/O operations will succeed. > > The second case is probably okay. The first we can do nothing about. > However, in either case we do need to make sure that memory allocations > do not require any writebacks. This suggests that we need to call > memalloc_noio_save() from within usb_unbind_interface(). I agree with the problem, but I fail to see why this issue would be specific to USB. Shouldn't this be done in the device core layer? Regards Oliver