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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 2B068C2BA19 for ; Tue, 14 Apr 2020 15:27:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D0C8420656 for ; Tue, 14 Apr 2020 15:27:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Nqem0qdV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D0C8420656 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5F3A68E0021; Tue, 14 Apr 2020 11:27:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 57D768E0007; Tue, 14 Apr 2020 11:27:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4446C8E0021; Tue, 14 Apr 2020 11:27:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0139.hostedemail.com [216.40.44.139]) by kanga.kvack.org (Postfix) with ESMTP id 24CEA8E0007 for ; Tue, 14 Apr 2020 11:27:07 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id DCF61824556B for ; Tue, 14 Apr 2020 15:27:06 +0000 (UTC) X-FDA: 76706838852.12.voice37_3d5dd3af8738 X-HE-Tag: voice37_3d5dd3af8738 X-Filterd-Recvd-Size: 6115 Received: from mail-wm1-f65.google.com (mail-wm1-f65.google.com [209.85.128.65]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Apr 2020 15:27:06 +0000 (UTC) Received: by mail-wm1-f65.google.com with SMTP id a201so14080813wme.1 for ; Tue, 14 Apr 2020 08:27:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=gw4uC/sRCdmFTjZYAO9cTpbsNH/HooDYCygstYON8EQ=; b=Nqem0qdV+qg+cMW+4u2b/7GAvdGk+2mQEI/57hBZEHg2vk3vPgBf26/AzMVNI5omno tXkRHF6fpJpZWizj/JMa8N779KcQ5he9WfBIq+vNKWv9Lw4AsvAVhP6gcLd8vnt5nHjo eYsHgtC58B6ttqoYlyCppheG49Isom9S7Y67nSQ95knFkdM22xn3G47GvEKLxhgRloQS BDmyD+0NMJkSw318waw8Xa3TwtozsXOM7ChclWGHbiUeMNvgQ1au+6go7mjOwhYIBMfG AyY9N6Kl7RkhUb0EueQO3gfY27nyWSjFORgMvH99bX8rt/b8mXLFwIwKb3so9aYLxU2y rbnQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=gw4uC/sRCdmFTjZYAO9cTpbsNH/HooDYCygstYON8EQ=; b=XBQg0P1BGV9Ob/97SB0w3JMoUAQ/zuJ0SMiBSPvKL4Tm+MnHsPa7xzr1M/ePw//9N9 N92YEoDHiFX03aJICWuslaeFadn7/Rdm3djo8tMQjgKI2AluD4J0W3xZI7SIwl3KhI1s J5Wt7tJqkON8Px9g+tIt2tDOFd9DjcThrc1dB2LV2Ej34ge5mXMYSQPYZ49QZbcLCVzT eO5yH3frea7SSE2n9vwX4VBhBgb9B0iDFkQFpkzf8hOyxcE9ExYJy2f46EL0Eu9Gcdja dPGCZBjdajy+3+gcrftgWeQ9BT20rLeqC4/9DjXzDUlH+vv3RCOQDErGVhLu0Pen+/NE NvJA== X-Gm-Message-State: AGi0PubFXgc4oHlk/aXe6qzMhVclkT3m14K0zGSEWLnhTMid1jGn7GRU ZWKWXrDR11baYHQNE6okXchjOtcoU9bxHHMsC9Mk+A== X-Google-Smtp-Source: APiQypIorIGWtF00v7sTL1dALGwGp9JmJpM4Zdp4sWNGtIIZYsvekR9dhyQ2EE28rRsAOTyNm17TpSonpN6sZF1pnr4= X-Received: by 2002:a7b:cd10:: with SMTP id f16mr417644wmj.21.1586878023955; Tue, 14 Apr 2020 08:27:03 -0700 (PDT) MIME-Version: 1.0 References: <20200325161249.55095-1-glider@google.com> <20200325161249.55095-35-glider@google.com> <20200325161905.GA19868@lst.de> <20200327170647.GA22758@lst.de> <20200328085233.GA26550@lst.de> In-Reply-To: <20200328085233.GA26550@lst.de> From: Alexander Potapenko Date: Tue, 14 Apr 2020 17:26:52 +0200 Message-ID: Subject: Re: [PATCH v5 34/38] kmsan: dma: unpoison memory mapped by dma_direct_map_page() To: Christoph Hellwig Cc: Marek Szyprowski , Robin Murphy , Vegard Nossum , Dmitry Vyukov , Marco Elver , Andrey Konovalov , Linux Memory Management List , Al Viro , Andreas Dilger , Andrew Morton , Andrey Ryabinin , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Christoph Hellwig , "Darrick J. Wong" , David Miller , Dmitry Torokhov , Eric Biggers , Eric Dumazet , Eric Van Hensbergen , Greg Kroah-Hartman , Harry Wentland , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jason Wang , Jens Axboe , Mark Rutland , "Martin K . Petersen" , Martin Schwidefsky , Matthew Wilcox , "Michael S. Tsirkin" , Michal Hocko , Michal Simek , Petr Mladek , Qian Cai , Randy Dunlap , Sergey Senozhatsky , Steven Rostedt , Takashi Iwai , "Theodore Ts'o" , Thomas Gleixner , Vasily Gorbik , Wolfram Sang Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Mar 28, 2020 at 9:52 AM Christoph Hellwig wrote: > > On Fri, Mar 27, 2020 at 07:46:08PM +0100, Alexander Potapenko wrote: > > > > Do you mean comparing the address to TASK_SIZE, or is there a more > > > > portable way to check that? > > > > > > !PageHighMem(page) implies the page has a kernel direct mapping. > > > > I tried adding this check and started seeing false positives because > > the virtio_ring driver actually uses highmem pages for DMA, and data > > from those pages is later copied to the kernel. > > Guess it's easier to just allow handling highmem pages? What problems > > do you anticipate? > > For PageHighMem(page), page_address(page) is not actually valid, so =D0= =86'm > not sure how your code in this patch even worked at all. Note that > all drivers (well, except for a few buggy legacy ones with workarounds) > can DMA from/to highmem. Hm, skipping PageHighMem pages works now, I must've been doing something wr= ong. Thanks, will add that check to v6. I found a bunch of other places in mm/kmsan/kmsan_shadow.c where we're using page_address(), but metadata pages are not supposed to reside in high memory. --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg