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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 A4D78C433DF for ; Tue, 30 Jun 2020 08:42:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 782E2206BE for ; Tue, 30 Jun 2020 08:42:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731623AbgF3Im5 (ORCPT ); Tue, 30 Jun 2020 04:42:57 -0400 Received: from 8bytes.org ([81.169.241.247]:50572 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728132AbgF3Imz (ORCPT ); Tue, 30 Jun 2020 04:42:55 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id E504F26B; Tue, 30 Jun 2020 10:42:52 +0200 (CEST) Date: Tue, 30 Jun 2020 10:42:51 +0200 From: Joerg Roedel To: Robin Murphy Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Prakash Gupta Subject: Re: [PATCH] iommu/iova: Don't BUG on invalid PFNs Message-ID: <20200630084251.GA28824@8bytes.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 02, 2020 at 02:08:18PM +0100, Robin Murphy wrote: > Unlike the other instances which represent a complete loss of > consistency within the rcache mechanism itself, or a fundamental > and obvious misconfiguration by an IOMMU driver, the BUG_ON() in > iova_magazine_free_pfns() can be provoked at more or less any time > in a "spooky action-at-a-distance" manner by any old device driver > passing nonsense to dma_unmap_*() which then propagates through to > queue_iova(). > > Not only is this well outside the IOVA layer's control, it's also > nowhere near fatal enough to justify panicking anyway - all that > really achieves is to make debugging the offending driver more > difficult. Let's simply WARN and otherwise ignore bogus PFNs. > > Reported-by: Prakash Gupta > Signed-off-by: Robin Murphy > --- > drivers/iommu/iova.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Applied without stable tag, thanks.