From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id C45F56B0253 for ; Mon, 13 Nov 2017 17:46:29 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id c123so8381430pga.17 for ; Mon, 13 Nov 2017 14:46:29 -0800 (PST) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id p4si6142277pgc.477.2017.11.13.14.46.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 Nov 2017 14:46:28 -0800 (PST) Subject: Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO) From: Dave Hansen References: <20170907173609.22696-1-tycho@docker.com> <20170907173609.22696-4-tycho@docker.com> <34454a32-72c2-c62e-546c-1837e05327e1@intel.com> <20170920223452.vam3egenc533rcta@smitten> <97475308-1f3d-ea91-5647-39231f3b40e5@intel.com> <20170921000901.v7zo4g5edhqqfabm@docker> <20171110010907.qfkqhrbtdkt5y3hy@smitten> <7237ae6d-f8aa-085e-c144-9ed5583ec06b@intel.com> Message-ID: <2aa64bf6-fead-08cc-f4fe-bd353008ca59@intel.com> Date: Mon, 13 Nov 2017 14:46:25 -0800 MIME-Version: 1.0 In-Reply-To: <7237ae6d-f8aa-085e-c144-9ed5583ec06b@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Tycho Andersen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, Marco Benatto , Juerg Haefliger , x86@kernel.org On 11/13/2017 02:20 PM, Dave Hansen wrote: > On 11/09/2017 05:09 PM, Tycho Andersen wrote: >> which I guess is from the additional flags in grow_dev_page() somewhere down >> the stack. Anyway... it seems this is a kernel allocation that's using >> MIGRATE_MOVABLE, so perhaps we need some more fine tuned heuristic than just >> all MOVABLE allocations are un-mapped via xpfo, and all the others are mapped. >> >> Do you have any ideas? > > It still has to do a kmap() or kmap_atomic() to be able to access it. I > thought you hooked into that. Why isn't that path getting hit for these? Oh, this looks to be accessing data mapped by a buffer_head. It (rudely) accesses data via: void set_bh_page(struct buffer_head *bh, ... bh->b_data = page_address(page) + offset; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org