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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB982C433FE for ; Thu, 10 Nov 2022 20:29:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231690AbiKJU32 (ORCPT ); Thu, 10 Nov 2022 15:29:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39362 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbiKJU3Z (ORCPT ); Thu, 10 Nov 2022 15:29:25 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF89EDB4 for ; Thu, 10 Nov 2022 12:28:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668112114; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=s3qJXkjwOhbGiwzYiY8uWUuyvmMsTBnM2XzNPe9LD9s=; b=AFu1fihkMf4yAkIY7TX22vzAQeuKR7aUoMOIM9pzFEM13Xvk2q3QZRe+eTtRgtIR6xtuPJ twKMb3OMQ3Aan8unZNR0/j+9djDYy4TeJ4YgAn8cwWkVGu87KpEOJ0MGOLutcexpXzbRVH m7nWmyIV22nDRN7oTtxMiX2IQKt5SZI= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-414-GMM8V5iYOdiaA8Ue18gi3Q-1; Thu, 10 Nov 2022 15:28:33 -0500 X-MC-Unique: GMM8V5iYOdiaA8Ue18gi3Q-1 Received: by mail-qt1-f197.google.com with SMTP id g3-20020ac84b63000000b003a529c62a92so2236556qts.23 for ; Thu, 10 Nov 2022 12:28:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=s3qJXkjwOhbGiwzYiY8uWUuyvmMsTBnM2XzNPe9LD9s=; b=YUhN6ARHhdcgT5WTyBoG5fe3/EgfprPEZbVMvqUC8jw8f81EoCyUYdQ4e30HIyfXs8 BHBfIBMBrHssxNSaZOJcGpx+jg096981tefWaTkfbx7VWZrBrt1zg0jRL/9Fop8mQctM T8l5IPw5nCMZHN15LM0axBKn30YW52R35pYh5TRYinpFCdeuxtVJumfpgvyDVnOi9B3w a+3qowrSoBQPNVMqbIy7RcDus/3IFIiknLph8Yx5L45Y1XlqdymkVhLJnMpL+2SEpXq0 dS8hgwKBLXZO0lHGTGLr6/kTj1rNDT/Iy3lBibmMPybD/YTB87PdhTKG69RGgq7Uxv2s 7jyA== X-Gm-Message-State: ACrzQf1rq3TfoOpY+uVau96xyqG5+gc/FEftx1YeDHMNkTFZK2yisLzt sQBbnl6FcxZVf2oTP0an1RfS7/6DlbSzufBdEswcoFEGa3TtZwisX4LESI/e4ukajB/89gONIGV iSM4pMzW2CtNyr9+cM7J57lsf X-Received: by 2002:a37:8246:0:b0:6f9:bc42:699a with SMTP id e67-20020a378246000000b006f9bc42699amr1741832qkd.496.1668112112502; Thu, 10 Nov 2022 12:28:32 -0800 (PST) X-Google-Smtp-Source: AMsMyM6U7SlZJzxRPAjnUqO/P0jD8kNSK5YAVkzCKarP217RdqceVGneo5WmOtTIZWolo1PJX/v1Lg== X-Received: by 2002:a37:8246:0:b0:6f9:bc42:699a with SMTP id e67-20020a378246000000b006f9bc42699amr1741822qkd.496.1668112112298; Thu, 10 Nov 2022 12:28:32 -0800 (PST) Received: from x1n (bras-base-aurron9127w-grc-46-70-31-27-79.dsl.bell.ca. [70.31.27.79]) by smtp.gmail.com with ESMTPSA id y201-20020a3764d2000000b006fa7b5ea2d1sm138582qkb.125.2022.11.10.12.28.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Nov 2022 12:28:31 -0800 (PST) Date: Thu, 10 Nov 2022 15:28:30 -0500 From: Peter Xu To: Nadav Amit Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mike Rapoport , Andrew Morton , Axel Rasmussen , Andrea Arcangeli , Ives van Hoorne Subject: Re: [PATCH 2/2] mm/uffd: Sanity check write bit for uffd-wp protected ptes Message-ID: References: <20221110151702.1478763-1-peterx@redhat.com> <20221110151702.1478763-3-peterx@redhat.com> <58FFF1A3-DC37-4D9F-ABF0-3C5DA519BFFB@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <58FFF1A3-DC37-4D9F-ABF0-3C5DA519BFFB@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 10, 2022 at 10:43:25AM -0800, Nadav Amit wrote: > On Nov 10, 2022, at 7:17 AM, Peter Xu wrote: > > > +#ifdef CONFIG_DEBUG_VM > > + /* > > + * Having write bit for wr-protect-marked present ptes is fatal, > > + * because it means the uffd-wp bit will be ignored and write will > > + * just go through. > > + * > > + * Use any chance of pgtable walking to verify this (e.g., when > > + * page swapped out or being migrated for all purposes). It means > > + * something is already wrong. Tell the admin even before the > > + * process crashes. We also nail it with wrong pgtable setup. > > + */ > > + WARN_ON_ONCE(wp && pte_write(pte)); > > How about VM_WARN_ON_ONCE() and no ifdef? Oops.. Will quickly respin, thanks. -- Peter Xu