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 49547CA9EA0 for ; Fri, 18 Oct 2019 16:22:32 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0701520854 for ; Fri, 18 Oct 2019 16:22:31 +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="u6zRMLK6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0701520854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9257C8E0006; Fri, 18 Oct 2019 12:22:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8D68C8E0003; Fri, 18 Oct 2019 12:22:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7EB288E0006; Fri, 18 Oct 2019 12:22:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0147.hostedemail.com [216.40.44.147]) by kanga.kvack.org (Postfix) with ESMTP id 584F08E0003 for ; Fri, 18 Oct 2019 12:22:31 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id F190252A3 for ; Fri, 18 Oct 2019 16:22:30 +0000 (UTC) X-FDA: 76057423260.12.boot96_6d373f45b6704 X-HE-Tag: boot96_6d373f45b6704 X-Filterd-Recvd-Size: 3582 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Fri, 18 Oct 2019 16:22:30 +0000 (UTC) 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=LwUa/9DnWiQZuReIg5yr6nI2SJa5OnN5AOdrmcykaYI=; b=u6zRMLK66ijWJufe0BeTNzH4D /frtc/nlVVKWc2Zd7HXWnuYpbn/cPoE2eh8Lj3HrxZ9GHA2OoC5fn0iDfm/R2IsVE5N3lOIryypP0 bm9HzfVQ7kjG8PPQsj0WWWlrQYvqKtW5auBjufStT+NEdNndaiMtl+vYbZjhDZyMxq7xVQTpXNnhR OetyzFzWwimMaMHFRDqp/2pZCa6kvPnjVN/ZOszvkdTfynrQOdDbqZjqdr71HD438KInwpg+AxxZw l7INa1Sy/dpigQT1zgm6cS+UCOwtJWHeYTQy0Rc7+c+buvrFj+bKhKqvWbf+MrrVogD4KHX50dhbm 2Bdhjp2xQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iLV1C-0003ib-Lu; Fri, 18 Oct 2019 16:22:22 +0000 Date: Fri, 18 Oct 2019 09:22:22 -0700 From: Matthew Wilcox To: glider@google.com Cc: Andrew Morton , Jens Axboe , Theodore Ts'o , Dmitry Torokhov , "Martin K . Petersen" , "Michael S. Tsirkin" , Christoph Hellwig , Eric Dumazet , Eric Van Hensbergen , Takashi Iwai , Vegard Nossum , Dmitry Vyukov , linux-mm@kvack.org Subject: Re: [PATCH RFC v1 23/26] kmsan: unpoisoning buffers from devices etc. Message-ID: <20191018162222.GM32665@bombadil.infradead.org> References: <20191018094304.37056-1-glider@google.com> <20191018094304.37056-24-glider@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191018094304.37056-24-glider@google.com> User-Agent: Mutt/1.12.1 (2019-06-15) 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 Fri, Oct 18, 2019 at 11:43:01AM +0200, glider@google.com wrote: > When data is copied to memory from a device KMSAN should treat it as > initialized. In most cases it's enough to just unpoison the buffer that > is known to come from a device. > In the case with __do_page_cache_readahead() and bio_copy_user_iov() we > have to mark the whole pages as ignored by KMSAN, as it's not obvious > where these pages are read again. ... > +++ b/mm/filemap.c > @@ -18,6 +18,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -2810,6 +2811,8 @@ static struct page *do_read_cache_page(struct address_space *mapping, > page = wait_on_page_read(page); > if (IS_ERR(page)) > return page; > + /* Assume all pages in page cache are initialized. */ > + kmsan_unpoison_shadow(page_address(page), PAGE_SIZE); Why would you do that? The page cache already keeps track of which pages are initialised -- the PageUptodate flag is set on them. Indeed, just adding a kmsan call to SetPageUptodate and __SetPageUptodate would probably be a very straightforward way of handling things, and probably means you can get rid of a lot of these other calls.