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_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7709EC47404 for ; Mon, 7 Oct 2019 06:12:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3D0522070B for ; Mon, 7 Oct 2019 06:12:15 +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="dPkKWkMl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727161AbfJGGMO (ORCPT ); Mon, 7 Oct 2019 02:12:14 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:51492 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726202AbfJGGMO (ORCPT ); Mon, 7 Oct 2019 02:12:14 -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=+RE624T/XEpD1avT5GfVdjNCs+ZJWmT9YjXQaqBZM7k=; b=dPkKWkMlKUhZZB5fhKh1ODpeT 16ZHXI5t8z+ddBZDENkb6wpNM1HVKrAosj7Kx1FCMvsG3y4CstGls4eJr+psTuhVbafWlARVZbDBy r18be1Pg7voEFXL8M37tV6X7RbxQ4hDCMRCYEIoJf8KRxQnyDRrfpUogj0h5XqrEiOF8i5EBLS/wd bQ71lm27gW6ic7Wq2zHwGP0MKH/7bdHidtC0AdBlXxA6RrI8Her5gSS3ZaL0YK/4bBSnRVedH+fYG CKA/0PWJiWAic++x07UfEEzYOapftae0PFbULcKoL0vh9s4E27jgwWtAszbsvT9SoSFPISpQHZVWl VYWnZrUHQ==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.2 #3 (Red Hat Linux)) id 1iHMFg-0007yp-9K; Mon, 07 Oct 2019 06:12:12 +0000 Date: Sun, 6 Oct 2019 23:12:12 -0700 From: Christoph Hellwig To: Jason Gunthorpe Cc: Alan Mikhak , linux-kernel@vger.kernel.org, martin.petersen@oracle.com, alexios.zavras@intel.com, ming.lei@redhat.com, gregkh@linuxfoundation.org, tglx@linutronix.de, christophe.leroy@c-s.fr, palmer@sifive.com, paul.walmsley@sifive.com Subject: Re: [PATCH] scatterlist: Validate page before calling PageSlab() Message-ID: <20191007061212.GA17978@infradead.org> References: <1569885755-10947-1-git-send-email-alan.mikhak@sifive.com> <20191001121623.GA22532@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191001121623.GA22532@ziepe.ca> User-Agent: Mutt/1.12.1 (2019-06-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 01, 2019 at 09:16:23AM -0300, Jason Gunthorpe wrote: > > If the virtual address obtained from ioremap() is not > > backed by a page struct, virt_to_page() returns an > > invalid page pointer. However, sg_copy_buffer() can > > correctly recover the original virtual address. Such > > addresses can successfully be assigned to scatterlist > > segments to transfer data across the PCI bus with > > sg_copy_buffer() if it were not for the crash in > > PageSlab() when called by sg_miter_stop(). > > I thought we already agreed in general that putting things that don't > have struct page into the scatter list was not allowed? Yes, that absolutely is the case.